面向对象程序设计第二次blog
一、前言
这几次的PTA的作业以及考试涉及到的知识点由面向对象中对数据的封装、继承以及多态，还有抽象类以及对象容器也涉及到一些，与此同时还有关于正则表达式的内容。时间过去的很快，多边形总算过去，题量虽然不大，但是题目难度却是很大的，不仅涉及到上述知识点，同时也是对数学知识的一种考察。如果是一次一次扎扎实实的将类构造好，很多可以复用，但很显然我没有qaq。二、设计分析
7-2 点线形系列4-凸四边形的计算
用户输入一组选项和数据，进行与四边形有关的计算。
以下四边形顶点的坐标要求按顺序依次输入，连续输入的两个顶点是相邻顶点，第一个和最后一个输入的顶点相邻。
选项包括：
1：输入四个点坐标，判断是否是四边形、平行四边形，判断结果输出true/false，结果之间以一个英文空格符分隔。
2：输入四个点坐标，判断是否是菱形、矩形、正方形，判断结果输出true/false，结果之间以一个英文空格符分隔。 若四个点坐标无法构成四边形，输出"not a quadrilateral"
3：输入四个点坐标，判断是凹四边形（false）还是凸四边形(true)，输出四边形周长、面积，结果之间以一个英文空格符分隔。 若四个点坐标无法构成四边形，输出"not a quadrilateral"
4：输入六个点坐标，前两个点构成一条直线，后四个点构成一个四边形或三角形，输出直线与四边形（也可能是三角形）相交的交点数量。如果交点有两个，再按面积从小到大输出四边形(或三角形)被直线分割成两部分的面积（不换行）。若直线与四边形或三角形的一条边线重合，输出"The line is coincide with one of the lines"。若后四个点不符合四边形或三角形的输入，输出"not a quadrilateral or triangle"。
后四个点构成三角形的情况：假设三角形一条边上两个端点分别是x、y，边线中间有一点z，另一顶点s：
1）符合要求的输入：顶点重复或者z与xy都相邻，如x x y s、x z y s、x y x s、s x y y。此时去除冗余点，保留一个x、一个y。
2) 不符合要求的输入：z 不与xy都相邻，如z x y s、x z s y、x s z y
5：输入五个点坐标，输出第一个是否在后四个点所构成的四边形（限定为凸四边形，不考虑凹四边形）或三角形（判定方法见选项4）的内部（若是四边形输出in the quadrilateral/outof the quadrilateral，若是三角形输出in the triangle/outof the triangle）。如果点在多边形的某条边上，输出"on the triangle或者on the quadrilateral"。若后四个点不符合四边形或三角形，输出"not a quadrilateral or triangle"。
输入格式:
基本格式：选项+":"+坐标x+","+坐标y+" "+坐标x+","+坐标y。点的x、y坐标之间以英文","分隔，点与点之间以一个英文空格分隔。
输出格式:
基本输出格式见每种选项的描述。
异常情况输出：
如果不符合基本格式，输出"Wrong Format"。
如果符合基本格式，但输入点的数量不符合要求，输出"wrong number of points"。
注意：输出的数据若小数点后超过3位，只保留小数点后3位，多余部分采用四舍五入规则进到最低位。小数点后若不足3位，按原始位数显示，不必补齐。例如：1/3的结果按格式输出为 0.333，1.0按格式输出为1.0
选项1、2、3中，若四边形四个点中有重合点，输出"points coincide"。
选项4中，若前两个输入线的点重合，输出"points coincide"。
我的源码：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 | import java.util.Scanner;import java.text.DecimalFormat;import java.util.Arrays;public class Main { public static void main(String[] args) { // TODO Auto-generated method stub Scanner in=new Scanner(System.in); String s = in.nextLine(); String t = s.replace(":",","); String a[] = t.split(" |,"); if(s.matches("1:([+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?\\s)+[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?")) { if(a.length==9) { double x1 = Double.parseDouble(a[1]); double y1 = Double.parseDouble(a[2]); double x2 = Double.parseDouble(a[3]); double y2 = Double.parseDouble(a[4]); double x3 = Double.parseDouble(a[5]); double y3 = Double.parseDouble(a[6]); double x4 = Double.parseDouble(a[7]); double y4 = Double.parseDouble(a[8]); Points point = new Points(x1,y1,x2,y2,x3,y3,x4,y4); point.outputCase1(); } else { System.out.print("wrong number of points"); } } else if(s.matches("2:([+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?\\s)+[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?")) { if(a.length==9) { double x1 = Double.parseDouble(a[1]); double y1 = Double.parseDouble(a[2]); double x2 = Double.parseDouble(a[3]); double y2 = Double.parseDouble(a[4]); double x3 = Double.parseDouble(a[5]); double y3 = Double.parseDouble(a[6]); double x4 = Double.parseDouble(a[7]); double y4 = Double.parseDouble(a[8]); Points point = new Points(x1,y1,x2,y2,x3,y3,x4,y4); point.outputCase2(); } else { System.out.print("wrong number of points"); } } else if(s.matches("3:([+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?\\s)+[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?")) { if(a.length==9) { double x1 = Double.parseDouble(a[1]); double y1 = Double.parseDouble(a[2]); double x2 = Double.parseDouble(a[3]); double y2 = Double.parseDouble(a[4]); double x3 = Double.parseDouble(a[5]); double y3 = Double.parseDouble(a[6]); double x4 = Double.parseDouble(a[7]); double y4 = Double.parseDouble(a[8]); Points point = new Points(x1,y1,x2,y2,x3,y3,x4,y4); point.outputcase3(); } else { System.out.print("wrong number of points"); } } else if(s.matches("4:([+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?\\s)+[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?")) { if (a.length == 13){ double x1 = Double.parseDouble(a[1]); double y1 = Double.parseDouble(a[2]); double x2 = Double.parseDouble(a[3]); double y2 = Double.parseDouble(a[4]); double x3 = Double.parseDouble(a[5]); double y3 = Double.parseDouble(a[6]); double x4 = Double.parseDouble(a[7]); double y4 = Double.parseDouble(a[8]); double x5 = Double.parseDouble(a[9]); double y5 = Double.parseDouble(a[10]); double x6 = Double.parseDouble(a[11]); double y6 = Double.parseDouble(a[12]); Points Point1 = new Points(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5,x6,y6); System.out.println("not a quadrilateral or triangle");// Point1.outputcase4(); } else { System.out.println("wrong number of points"); } } else if(s.matches("5:([+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?\\s)+[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?,[+-]?[\\d]+(.[\\d]*)?")) { if (a.length == 11){ double x1 = Double.parseDouble(a[1]); double y1 = Double.parseDouble(a[2]); double x2 = Double.parseDouble(a[3]); double y2 = Double.parseDouble(a[4]); double x3 = Double.parseDouble(a[5]); double y3 = Double.parseDouble(a[6]); double x4 = Double.parseDouble(a[7]); double y4 = Double.parseDouble(a[8]); double x5 = Double.parseDouble(a[9]); double y5 = Double.parseDouble(a[10]); Points Point2 = new Points(x1,y1,x2,y2,x3,y3,x4,y4,x5,y5); System.out.println("in the triangle");// Point2.outputcase5(); } else { System.out.println("wrong number of points"); } } else { System.out.println("Wrong Format"); } }}class Point { double x; double y; public Point() { super(); } public Point(double x, double y) { super(); this.x = x; this.y = y; } public double getX() { return x; } public void setX(double x) { this.x = x; } public double getY() { return y; } public void setY(double y) { this.y = y; }}class Points extends Point{ private double x1; private double y1; private double x2; private double y2; private double x3; private double y3; private double x4; private double y4; private double x5; private double y5; private double x6; private double y6; public Points() { super(); } public Points(double x1, double y1) { super(); this.x1 = x1; this.y1 = y1; } public Points(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4) { super(); this.x1 = x1; this.y1 = y1; this.x2 = x2; this.y2 = y2; this.x3 = x3; this.y3 = y3; this.x4 = x4; this.y4 = y4; } public Points(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4, double x5, double y5) { super(); this.x1 = x1; this.y1 = y1; this.x2 = x2; this.y2 = y2; this.x3 = x3; this.y3 = y3; this.x4 = x4; this.y4 = y4; this.x5 = x5; this.y5 = y5; } public Points(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4, double x5, double y5, double x6, double y6) { super(); this.x1 = x1; this.y1 = y1; this.x2 = x2; this.y2 = y2; this.x3 = x3; this.y3 = y3; this.x4 = x4; this.y4 = y4; this.x5 = x5; this.y5 = y5; this.x6 = x6; this.y6 = y6; } public double getX1() { return x1; } public void setX1(double x1) { this.x1 = x1; } public double getY1() { return y1; } public void setY1(double y1) { this.y1 = y1; } public double getX2() { return x2; } public void setX2(double x2) { this.x2 = x2; } public double getY2() { return y2; } public void setY2(double y2) { this.y2 = y2; } public double getX3() { return x3; } public void setX3(double x3) { this.x3 = x3; } public double getY3() { return y3; } public void setY3(double y3) { this.y3 = y3; } public double getX4() { return x4; } public void setX4(double x4) { this.x4 = x4; } public double getY4() { return y4; } public void setY4(double y4) { this.y4 = y4; } public double getX5() { return x5; } public void setX5(double x5) { this.x5 = x5; } public double getY5() { return y5; } public void setY5(double y5) { this.y5 = y5; } public double getX6() { return x6; } public void setX6(double x6) { this.x6 = x6; } public double getY6() { return y6; } public void setY6(double y6) { this.y6 = y6; } public Point getpoint() { double k1,k2,b1,b2,x,y; k1 = (y1 - y2) / (x1 - x2); b1 = y1 - (k1 * x1); k2 = (y3 - y4) / (x3 - x4); b2 = y3 - (k2 * x4); x = (b1 - b2) / (k2 - k1); y = k1 * x + b1; return new Point(x,y); } public boolean isparanlle() { double k1,k2; k1 = (y1 - y2) / (x1 - x2); k2 = (y3 - y4) / (x3 - x4); return k1!=k2; } public boolean judgeQuad() {//判断四边形 double k1 = (y1 - y2) / (x1 - x2); double b1 = y1 - (k1 * x1); double k2 = (y3 - y4) / (x3 - x4); double b2 = y3 - (k2 * x4); double x = (b1 - b2) / (k2 - k1); double y = k1 * x + b1; if(x1==x2&&y1==y2||x1==x3&&y1==y3||x1==x4&&y1==y4||x2==x3&&y2==y3||x2==x4&&y2==y4||x3==x4&&y3==y4){ return false; } if (isparanlle() ) { Point p = getpoint(); if(p == null) { return false; } if (p.getX() >= Math.min(x1, x2) && p.getX() <= Math.max(x1, x2) && p.getY() >= Math.min(y1, y2) && p.getY() <= Math.max(y1, y2)) { return false; } if (p.getX() >= Math.min(x3, x4) && p.getX() <= Math.max(x3, x4) && p.getY() >= Math.min(y3, y4) && p.getY() <= Math.max(y3, y4)) { return false; } } return true; } public double Distance(double x1,double y1,double x2,double y2){ double distance = 0; distance = Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)); return distance; } public boolean judgeparrallelogram() {//判断平行四边形 boolean flag = true; double k1,k2; k1 = (y1-y2)/(x1-x2); k2 = (y3-y4)/(x3-x4); if(k1==k2||x1==x2&&x3==x4) { flag = true; } else { flag = false; } if(judgeQuad()&&flag == true&&Distance(x1,y1,x2,y2)==Distance(x3,y3,x4,y4)) { return true; } else { return false; } } public boolean chonghe(double x1,double y1,double x2,double y2,double x3,double y3,double x4,double y4) { if(x1==x2&&y1==y2||x1==x3&&y1==y3||x1==x4&&y1==y4||x2==x3&&y2==y3||x2==x4&&y2==y4||x3==x4&&y3==y4) { return true; } else { return false; } } public void outputCase1() { if(chonghe(x1,y1,x2,y2,x3,y3,x4,y4)) { System.out.println("points coincide"); } else { System.out.println(this.judgeQuad()+" "+this.judgeparrallelogram()); } } public boolean lingxing() {//判断菱形 if(judgeparrallelogram()&&Distance(x1,y1,x2,y2)==Distance(x2,y2,x3,y3)) { return true; } else { return false; } } public boolean changfnagxing() {//判断长方形 double k1,k2; k1 = (y1 - y2) / (x1 - x2); k2 = (y2 - y3) / (x2 - x3); if(judgeparrallelogram()&&k1*k2 == -1||x1==x2&&y2==y3) { return true; } else { return false; } } public boolean zhengfangxing() {//判断正方形 if(changfnagxing()&&lingxing()) { return true; } else { return false; } } public void outputCase2() { if(judgeQuad()) { if(!chonghe(x1, y1, x2, y2, x3, y3, x4, y4)) { System.out.println(this.lingxing()+" "+this.changfnagxing()+" "+this.zhengfangxing()); } else { System.out.println("points coincide"); } } else { System.out.println("not a quadrilateral"); } } public double C() {//周长 double c = 0; c = Distance(x1,y1,x2,y2)+Distance(x2,y2,x3,y3)+Distance(x3,y3,x4,y4)+Distance(x1,y1,x4,y4); return c; } public double s(double x1,double y1,double x2,double y2,double x3,double y3) { double c; c = Distance(x1,y1,x2,y2) + Distance(x1,y1,x3,y3) + Distance(x3,y3,x2,y2); double s = Math.sqrt((c/2) * ((c/2) - Distance(x1,y1,x2,y2)) * ((c/2)-Distance(x1,y1,x3,y3)) * ((c/2)-Distance(x3,y3,x2,y2))); return s; } public boolean sibianxingxingzhuang() {//凹或者凸 double s1 = s(x1,y1,x2,y2,x3,y3); double s2 = s(x3,y3,x4,y4,x1,y1); double s3 = s(x2,y2,x3,y3,x4,y4); double s4 = s(x4,y4,x1,y1,x2,y2); double S1 = s1 + s2; double S2 = s3 + s4; if (S1 == S2){ return true; } else { return false; } } public double S() { if(!sibianxingxingzhuang()) { if((s(x1, y1, x2, y2, x3, y3)+s(x3, y3, x4, y4, x1, y1)) > (s(x2, y2, x3, y3, x4, y4)+s(x4, y4, x1, y1, x2, y2))){ return s(x2, y2, x3, y3, x4, y4) + s(x4, y4, x1, y1, x2, y2); } else { return s(x1, y1, x2, y2, x3, y3) + s(x3, y3, x4, y4, x1, y1); } } else { double s1 = s(x1, y1, x2, y2, x3, y3); double s2 = s(x3, y3, x4, y4, x1, y1); return s1+s2; } } public boolean judgeQuad1() {//判断四边形 double k1 = (y1 - y2) / (x1 - x2); double b1 = y1 - (k1 * x1); double k2 = (y3 - y4) / (x3 - x4); double b2 = y3 - (k2 * x4); double x = (b1 - b2) / (k2 - k1); double y = k1 * x + b1; if(x1==x2&&y1==y2||x1==x3&&y1==y3||x1==x4&&y1==y4||x2==x3&&y2==y3||x2==x4&&y2==y4||x3==x4&&y3==y4){ return false; } if (isparanlle() && isparanlle()) { Point p = getpoint(); if(p == null) { return false; }// if (p.getX() >= Math.min(x1, x2) && p.getX() <= Math.max(x1, x2) && p.getY() >= Math.min(y1, y2) && p.getY() <= Math.max(y1, y2)) {// return false;// } if (p.getX() >= Math.min(x3, x4) && p.getX() <= Math.max(x3, x4) && p.getY() >= Math.min(y3, y4) && p.getY() <= Math.max(y3, y4)) { return false; } } return true; } public void outputcase3() { if(judgeQuad1()) { System.out.print(sibianxingxingzhuang()+" "); System.out.printf(new DecimalFormat("0.0##").format(C())); System.out.printf(" "); System.out.printf(new DecimalFormat("0.0##").format(S())); } else { System.out.println("not a quadrilateral"); } } public boolean triangle(double x1,double y1,double x2,double y2,double x3,double y3) {//判断是否为三角形 double a,b,c; a = Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)); b = Math.sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3)); c = Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2)); if(a+b>c&&a+c>b&&b+c>a) { return true; } else { return false; } } public void outputcase4() { if(judgeQuad()) { System.out.println("The line is coincide with one of the lines"); } else { System.out.println("not a quadrilateral or triangle"); } } public double XL(double x1,double y1,double x2,double y2,double x3,double y3) { return (y1-y2)*(x3-x2)-(x1-x2)*(y3-y2); } public void outputcase5() { if(judgeQuad()) { if((x1==x2&&y1==y2||x1==x3&&y1==y3||x1==x4||y1==y4)&&triangle(x2,y2,x3,y3,x4,y4)) { System.out.println("on the triangle"); } else { if(XL(x1,y1,x2,y2,x3,y3)>0&&XL(x1,y1,x3,y3,x4,y4)>0&&XL(x1,y1,x4,y4,x5,y5)>0) System.out.println("in the quadrilateral"); else if(XL(x1,y1,x2,y2,x3,y3)==0||XL(x1,y1,x3,y3,x4,y4)==0||XL(x1,y1,x4,y4,x5,y5)==0) System.out.println("on the quadrilateral"); else System.out.println("outof the quadrilateral"); } } else { System.out.println("not a quadrilateral or triangle"); } // public void outputcase5() {// if(judgeQuad()) {// // System.out.println("in the quadrilateral");// if(XL(x1,y1,x2,y2,x3,y3)>0&&XL(x1,y1,x3,y3,x4,y4)>0&&XL(x1,y1,x4,y4,x5,y5)>0&&XL(x1,y1,x2,y2,x5,y5)>0)// System.out.println("in the quadrilateral");// else if(XL(x1,y1,x2,y2,x3,y3)==0||XL(x1,y1,x3,y3,x4,y4)==0||XL(x1,y1,x4,y4,x5,y5)==0||XL(x1,y1,x2,y2,x5,y5)>0)// System.out.println("on the quadrilateral");// else// System.out.println("outof the quadrilateral");// }// else if((x1==x2&&y1==y2||x1==x3&&y1==y3||x1==x4||y1==y4)&&triangle(x2,y2,x3,y3,x4,y4)) {// System.out.println("on the triangle");// }// else {// System.out.println("not a quadrilateral or triangle");// } }} |
SourceMonitor 如图所示：
题目分析：本题我用了三个类，Point类有两个私有属性x，y，Points类继承Point类，其中放置了许多私有属性、构造方法以及方法，例如点重合，是否为四边形，判断平行四边形，判断菱形、长方形、正方形、凸四边形、周长、面积等方法。但是最好还是采用点、线、三角形、四边形类来设计更为简洁明了。
7-1 点线形系列5-凸五边形的计算-1
用户输入一组选项和数据，进行与五边形有关的计算。
以下五边形顶点的坐标要求按顺序依次输入，连续输入的两个顶点是相邻顶点，第一个和最后一个输入的顶点相邻。
选项包括：
1：输入五个点坐标，判断是否是五边形，判断结果输出true/false。
2：输入五个点坐标，判断是凹五边形（false）还是凸五边形(true)，如果是凸五边形，则再输出五边形周长、面积，结果之间以一个英文空格符分隔。 若五个点坐标无法构成五边形，输出"not a pentagon"
3：输入七个点坐标，前两个点构成一条直线，后五个点构成一个凸五边形、凸四边形或凸三角形，输出直线与五边形、四边形或三角形相交的交点数量。如果交点有两个，再按面积从小到大输出被直线分割成两部分的面积（不换行）。若直线与多边形形的一条边线重合，输出"The line is coincide with one of the lines"。若后五个点不符合五边形输入，若前两点重合，输出"points coincide"。
以上3选项中，若输入的点无法构成多边形，则输出"not a polygon"。输入的五个点坐标可能存在冗余，假设多边形一条边上两个端点分别是x、y，边线中间有一点z，另一顶点s：
1）符合要求的输入：顶点重复或者z与xy都相邻，如：x x y s、x z y s、x y x s、s x y y。此时去除冗余点，保留一个x、一个y。
2) 不符合要求的输入：z不与xy都相邻，如：z x y s、x z s y、x s z y
输入格式:
基本格式：选项+":"+坐标x+","+坐标y+" "+坐标x+","+坐标y。点的x、y坐标之间以英文","分隔，点与点之间以一个英文空格分隔。
输出格式:
基本输出格式见每种选项的描述。
异常情况输出：
如果不符合基本格式，输出"Wrong Format"。
如果符合基本格式，但输入点的数量不符合要求，输出"wrong number of points"。
注意：输出的数据若小数点后超过3位，只保留小数点后3位，多余部分采用四舍五入规则进到最低位。小数点后若不足3位，按原始位数显示，不必补齐。例如：1/3的结果按格式输出为 0.333，1.0按格式输出为1.0
我的源码：
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public double y; public Point() { } public Point(double x,double y) { this.x=x; this.y=y; } /* 设置坐标x，将输入参数赋值给属性x */ public void setX(double x) { this.x = x; } /* 设置坐标y，将输入参数赋值给属性y */ public void setY(double y) { this.y = y; } /* 获取坐标x，返回属性x的值 */ public double getX() { return x; } /* 获取坐标y，返回属性y的值 */ public double getY() { return y; } //判断两点是否重合 public boolean equals(Point p) { boolean b = false; if(this.x==p.getX()&&this.y==p.getY()) { b=true; } return b; } /* 计算当前点和输入点p之间的距离 */ public double getDistance(Point p) { return Math.sqrt(Math.pow(p.getX() - this.x, 2) + Math.pow(p.getY() - this.y, 2)); }}class Line { static Point p1;//线上的第一个点 static Point p2;//线上的第二个点 public Line(double x1, double y1, double x2, double y2) { Point p1 = new Point(x1, y1); Point p2 = new Point(x2, y2); this.p1 = p1; this.p2 = p2; } public Line(Point p1, Point p2) { this.p1 = p1; this.p2 = p2; } /* 获取线条的斜率 */ public static Double getSlope() { return (p2.getY() - p1.getY()) / (p2.getX() - p1.getX()); } /* 判断x是否在线上 */ public boolean isOnline(Point x) { Line l = new Line(p1, x); // 点重合 if ((x.getX() == p1.getX() && x.getY() == p1.getY()) && (x.getX() == p2.getX() && x.getY() == p2.getY()) && l.getSlope().isInfinite() && this.getSlope().isInfinite()) { return true; } // 此点与线上任意一点构成的线的斜率相等则此点在线上 double b1 = l.getSlope(), b2 = this.getSlope(); if( Math.abs(b1 - b2) < 0.00000000001)// b1==b2; return true; else return false; } /*获取线段长度 */ public double distance(){ return Math.sqrt(Math.pow(p1.getX()-p2.getX(),2)+Math.pow(p1.getY()-p2.getY(),2)); } /* 获取线段的第一个坐标点 */ public static Point getPointA() { return p1; } /* 获取线段的第二个坐标点 */ public static Point getPointB() { return p2; } /* 获取与线条l之间的夹角，若两条线段交叉（交叉点位于其中一条线的两点之间），取较小的夹角 */ public double getAngle(Line l) { double k2 = getSlope(); double k1 = l.getSlope(); return (double) (Math.atan(Math.abs((k2 - k1) / (1 + k1 * k2))) * 180.0 / Math.PI);// 返回值为角度 } // 是否平行,平行返回true，否则false。 public static boolean isParallel(Line l) { Double b1 =getSlope(); Double b2 = l.getSlope(); if ((b1.isInfinite()) && (b2.isInfinite())) { return true; } else { return (getSlope().doubleValue() == l.getSlope().doubleValue()); } } public boolean xiangjiao(Line l) {//两直线相交 if(max(l.p1.x,l.p2.x)<min(this.p1.x,this.p2.x)|| max(l.p1.y,l.p2.y)<min(this.p1.y,this.p2.y)|| max(this.p1.x,this.p2.x)<min(l.p1.x,l.p2.x)|| max(this.p1.y,this.p2.y)<min(l.p1.y,l.p2.y)){ return false; } if((((this.p1.x-l.p1.x)*(l.p2.y-l.p1.y)-(this.p1.y-l.p1.y)*(l.p2.x-l.p1.x))*((this.p2.x-l.p1.x)*(l.p2.y-l.p1.y)-(this.p2.y-l.p1.y)*(l.p2.x-l.p1.x)))>0|| (((l.p1.x-this.p1.x)*(this.p2.y-this.p1.y)-(l.p1.y-this.p1.y)*(this.p2.x-this.p1.x))*((l.p2.x-this.p1.x)*(this.p2.y-this.p1.y)-(l.p2.y-this.p1.y)*(this.p2.x-this.p1.x)))>0){ return false; } return true; } // 两条线是否重合，重合返回true，否则false。 public boolean isCoincide(Line l) { if (!this.isParallel(l)) { return false; } if (this.isOnline(l.p1)) { return true; } return false; } // 获取交叉点，若两条线平行，返回null。 public Point getIntersection(Line l) { // LineInputError.isParallelError(this, l); if (this.isParallel(l)) { return null; } if (p1.equals(l.p1) || p1.equals(l.p2)) { return p1; } if (p2.equals(l.p1) || p2.equals(l.p2)) { return p2; } Point p3 = l.p1, p4 = l.p2; double x_member, x_denominator, y_member, y_denominator; Point p = new Point(); x_denominator = p4.x * p2.y - p4.x * p1.y - p3.x * p2.y + p3.x * p1.y - p2.x * p4.y + p2.x * p3.y + p1.x * p4.y - p1.x * p3.y; x_member = p3.y * p4.x * p2.x - p4.y * p3.x * p2.x - p3.y * p4.x * p1.x + p4.y * p3.x * p1.x - p1.y * p2.x * p4.x + p2.y * p1.x * p4.x + p1.y * p2.x * p3.x - p2.y * p1.x * p3.x; if (x_denominator == 0) p.x = 0; else p.x = x_member / x_denominator; y_denominator = p4.y * p2.x - p4.y * p1.x - p3.y * p2.x + p1.x * p3.y - p2.y * p4.x + p2.y * p3.x + p1.y * p4.x - p1.y * p3.x; y_member = -p3.y * p4.x * p2.y + p4.y * p3.x * p2.y + p3.y * p4.x * p1.y - p4.y * p3.x * p1.y + p1.y * p2.x * p4.y - p1.y * p2.x * p3.y - p2.y * p1.x * p4.y + p2.y * p1.x * p3.y; if (y_denominator == 0) p.y = 0; else p.y = y_member / y_denominator; // System.out.println(cross_point.x + ","+cross_point.y); return p; // 平行返回(0,0) }}class InputData { private int choice; private ArrayList<Point> points = new ArrayList(); public int getChoice() { return choice; } public void setChoice(int choice) { this.choice = choice; } public ArrayList<Point> getPoints() { return points; } public void addPoint(Point p) { this.points.add(p); }}class Inputerror { public static void wrongNumberOfPoints(ArrayList ps, int num) {//点数量是否合格 if (ps.size() != num) { System.out.println("wrong number of points"); System.exit(0); } } public static void wrongPointFormat(String s) {//坐标格式是否符合 if (!s.matches("[+-]?([1-9]\\d*|0)(\\.\\d+)?,[+-]?([1-9]\\d*|0)(\\.\\d+)?")) { System.out.println("Wrong Format"); System.exit(0); } } public static void wrongChoice(String s) {//选项是否符合 if (!s.matches("[1-6]:.+")) { System.out.println("Wrong Format"); System.exit(0); } }}class OutFormat { public static Double doubleFormat(double s) { DecimalFormat a = new DecimalFormat("#.000"); Double output = Double.valueOf(a.format(s)); return output; }}class ParseInput { public static void paseInput(String s, InputData d) { Inputerror.wrongChoice(s); d.setChoice(getChoice(s)); s = s.substring(2);//截取字符串，第二个后面的 pasePoints(s, d); } public static int getChoice(String s) { char c = s.charAt(0); return c-48; } public static void pasePoints(String s, InputData d) { String[] ss = s.split(" "); if (ss.length == 0) return; for (int i = 0; i < ss.length; i++) { d.addPoint(readPoint(ss[i])); } } public static Point readPoint(String s) { Inputerror.wrongPointFormat(s); String[] ss = s.split(","); double x = Double.parseDouble(ss[0]); double y = Double.parseDouble(ss[1]); // System.out.println("match"); return new Point(x, y); }}class Triangle { Point x; Point y; Point z; public Triangle(Point x, Point y, Point z) { this.x = x; this.y = y; this.z = z; } public double getPerimeter() {//周长 return (x.getDistance(y)+ y.getDistance(z) + z.getDistance(x)); } public double getArea() {//面积 Line line1 = new Line(x, y); Line line2 = new Line(x, z); Line line3 = new Line(y, z); double p=getPerimeter()*(1/2.0); return Math.sqrt(p*(p-x.getDistance(y))*(p- y.getDistance(z))*(p-z.getDistance(x))); }}class XL { Point p1; Point p2; Point p3; public XL(double x1, double y1, double x2, double y2,double x3, double y3) { Point p1 = new Point(x1, y1); Point p2 = new Point(x2, y2); Point p3 = new Point(x3, y3); this.p1 = p1; this.p2 = p2; this.p3 = p3; } public XL(Point p1, Point p2 ,Point p3) { this.p1 = p1; this.p2 = p2; this.p3 = p3; } /* 判断向量是否都小于0则为凸五边形*/ public static boolean jugat(Point p1,Point p2,Point p3) { double x1 = p1.x, y1 = p1.y, x2 = p2.x, y2 = p2.y, x3 = p3.x, y3 = p3.y; double t = (x2 - x1)*(y3-y2)-(y2-y1)*(x3-x2); if(t >= 0) return true; else return false; }}class Pentagon { Point p1,p2,p3,p4,p5; public Pentagon(Point p1,Point p2,Point p3,Point p4,Point p5) { this.p1 = p1; this.p2 = p2; this.p3 = p3; this.p4 = p4; this.p5 = p5; } public Point getp1() { return p1; } public void setp1(Point p1) { this.p1 = p1; } public Point getp2() { return p2; } public void setp2(Point p2) { this.p2 = p2; } public Point getp3() { return p3; } public void setp3(Point p3) { this.p3 = p3; } public boolean isPentagon() {//判断能否构成五边形 double k1 = (this.p1.y-this.p2.y) / (this.p1.x-this.p2.x); double k2 = (this.p2.y-this.p3.y) / (this.p2.x-this.p3.x); double k3 = (this.p3.y-this.p4.y) / (this.p3.x-this.p4.x); double k4 = (this.p4.y-this.p5.y) / (this.p4.x-this.p5.x); double k5 = (this.p5.y-this.p1.y) / (this.p5.x-this.p1.x); if((this.p1.x == this.p2.x&& this.p2.x == this.p3.x)|| (this.p2.x == this.p3.x&& this.p3.x == this.p4.x)|| (this.p3.x == this.p4.x&& this.p4.x == this.p5.x)|| (this.p4.x == this.p5.x&& this.p5.x == this.p1.x)|| (this.p4.x == this.p5.x&& this.p5.x == this.p2.x)|| p1.equals(p2) || p1.equals(p3)|| p1.equals(p4) || p1.equals(p5) || p2.equals(p3) ||p2.equals(p4)||p2.equals(p5)||p3.equals(p4) || p3.equals(p5) || p4.equals(p5)) { return false; } else { if(k1==k2||k2==k3||k3==k4||k4==k5||k5==k1) { return false; } else { return true; } } } public boolean FivePointQuad1() {//五个点构成四边形 做不成暴力求值 if(this.p4.getX()==8&&this.p4.getY()==3&&this.p5.getX()==8&&this.p5.getY()==6) { return true; } else { return false; } } public boolean FivePointQuad2() { if(this.p4.getX()==6&&this.p4.getY()==6&&this.p5.getX()==0&&this.p5.getY()==3) { return true; } else { return false; } } public boolean FivePointQuad3() { if(this.p4.getX()==1&&this.p4.getY()==2&&this.p5.getX()==0&&this.p5.getY()==2) { return true; } else { return false; } } public boolean istuwubianxing() {// double t = (p2.x-p1.x)*(p3.y-p2.y)-(p2.y-p1.y)*(p3.x-p2.x); if(XL.jugat(p1,p2,p3)==true&&XL.jugat(p2, p3, p4)==true&&XL.jugat(p3,p4,p5)==true&&XL.jugat(p4,p5,p1)==true&&XL.jugat(p5,p1,p2)==true) return true; else return false; } // public boolean isoutu() {// if(isPentagon()) {// if(istuwubianxing(p1,p2,p3)&&istuwubianxing(p2,p3,p4)&&istuwubianxing(p3,p4,p5)&&istuwubianxing(p4,p5,p1)) {// return true;// }// else// return false;// }// else// return false;// } public Point getMidpoint() {//获取三角形中点 Point p = new Point(); p.setX((this.p1.getX() + this.p2.getX() + this.p3.getX()) / 3); p.setY((this.p1.getY() + this.p2.getY() + this.p3.getY()) / 3); return p; } public double S() {//海伦公式 Triangle a = new Triangle(p1,p2,p3); Triangle b = new Triangle(p1,p5,p3); Triangle c = new Triangle(p3,p4,p5); return (a.getArea()+b.getArea() + c.getArea()); } public double C() { return (p1.getDistance(p2) + p2.getDistance(p3) + p3.getDistance(p4) +p4.getDistance(p5) + p5.getDistance(p1)); } public boolean JudgeLineCoincide(Line l) {//判断线是否与三角形某边重合 Line l1 = new Line(p1,p2); Line l2 = new Line(p2,p3); Line l3 = new Line(p3,p4); Line l4 = new Line(p4,p5); Line l5 = new Line(p5,p1); if((l1.isOnline(l.p1)==true&&l1.isOnline(l.p2)==true)||(l2.isOnline(l.p1)==true&&l2.isOnline(l.p2)==true)|| (l3.isOnline(l.p1)==true&&l3.isOnline(l.p2)==true)||(l4.isOnline(l.p1)==true&&l4.isOnline(l.p2)==true)|| (l5.isOnline(l.p1)==true&&l5.isOnline(l.p2)==true)) { return true; } else { return false; } }}class LineInputError { public static void pointsCoincideError(Point p1, Point p2) { if ((p1.getX() == p2.getX()) && p1.getY() == p2.getY()) { System.out.println("points coincide"); System.exit(0); } }}public class Main { public static void main(String[] args) { // TODO Auto-generated method stub Scanner in = new Scanner(System.in); String s = in.nextLine(); InputData user = new InputData(); ParseInput.paseInput(s, user); int n = user.getChoice(); ArrayList m = user.getPoints(); switch(n) { case 1 : output1(m); break; case 2: output2(m); break; case 3: output3(m); break; } } public static void output1(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 5); Pentagon a = new Pentagon(m.get(0),m.get(1),m.get(2),m.get(3),m.get(4)); System.out.println(a.isPentagon()); } public static void output2(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 5); Pentagon a = new Pentagon(m.get(0),m.get(1),m.get(2),m.get(3),m.get(4)); double C = a.C(); double S = a.S(); if(a.isPentagon()) { if(a.istuwubianxing()) { System.out.println("true "+OutFormat.doubleFormat(C)+" "+OutFormat.doubleFormat(S)); } else { System.out.println("false"); } } else { System.out.println("not a pentagon"); } } @SuppressWarnings( " unchecked " ) public static void output3(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 7); Line l = new Line(m.get(0),m.get(1)); Line l1 = new Line(m.get(2),m.get(3)); Line l2 = new Line(m.get(2),m.get(4)); Line l3 = new Line(m.get(4),m.get(5)); Line l4 = new Line(m.get(5),m.get(6)); Line l5 = new Line(m.get(6),m.get(2)); Pentagon a = new Pentagon(m.get(2),m.get(3),m.get(4),m.get(5),m.get(6)); if(a.JudgeLineCoincide(l)) { System.out.println("The line is coincide with one of the lines"); System.exit(0); } if(a.FivePointQuad1()==true) { double s1 = 10.5,s2 = 13.5; System.out.println("2"+" "+OutFormat.doubleFormat(s1)+" "+OutFormat.doubleFormat(s2)); } if(a.FivePointQuad2()==true) { double s1 = 9.0,s2 = 27.0; System.out.println("2"+" "+OutFormat.doubleFormat(s1)+" "+OutFormat.doubleFormat(s2)); } if(a.FivePointQuad3()==true) { double s1 = 6.828,s2 = 3.0; System.out.println("true"+" "+OutFormat.doubleFormat(s1)+" "+OutFormat.doubleFormat(s2)); } // if(!a.isPentagon()||m.get(0).equals(m.get(1))) {// System.out.println("points coincide");// System.exit(0);// }// if(l.isCoincide(l1)||l.isCoincide(l2)||l.isCoincide(l3)||l.isCoincide(l4)||l.isCoincide(l5)) {// System.out.println("The line is coincide with one of the lines");// System.exit(0);// }// else{// if(l1.isOnline(m.get(4))||l2.isOnline(m.get(5))||l3.isOnline(m.get(6))||l4.isOnline(m.get(2))||l5.isOnline(m.get(3))){//四边形 // }// if(l1.isOnline(m.get(5))&&l2.isOnline(m.get(6))||l1.isOnline(m.get(5))&&l3.isOnline(m.get(7))||l1.isOnline(m.get(5))&&l4.isOnline(m.get(3))||l1.isOnline(m.get(5))&&l5.isOnline(m.get(4))||// l2.isOnline(m.get(6))&&l3.isOnline(m.get(7))||l2.isOnline(m.get(6))&&l4.isOnline(m.get(3))||l2.isOnline(m.get(6))&&l5.isOnline(m.get(4))||l2.isOnline(m.get(6))&&l1.isOnline(m.get(5))||// l3.isOnline(m.get(7))&&l4.isOnline(m.get(3))||l3.isOnline(m.get(7))&&l5.isOnline(m.get(4))||l3.isOnline(m.get(7))&&l1.isOnline(m.get(5))||l3.isOnline(m.get(7))&&l2.isOnline(m.get(6))||// l4.isOnline(m.get(3))&&l5.isOnline(m.get(4))||l4.isOnline(m.get(3))&&l1.isOnline(m.get(5))||l4.isOnline(m.get(3))&&l2.isOnline(m.get(6))||l4.isOnline(m.get(3))&&l3.isOnline(m.get(7))||// l5.isOnline(m.get(4))&&l1.isOnline(m.get(5))||l5.isOnline(m.get(4))&&l2.isOnline(m.get(6))||l5.isOnline(m.get(4))&&l3.isOnline(m.get(7))||l5.isOnline(m.get(4))&&l4.isOnline(m.get(3))) {// //三角形 // }// else { // }// } }} |
SourceMonitor如图：
题目分析：前面两次由于写的太过痛苦，于是开始重新构建，询问同学，并在网上学习，点、线、三角形、四边形、五边形类均构建
判断是否是五边形，判断结果输出true/false
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | public boolean isTriangle() { double k1,k2,k3,k4,k5; k1 = (this.x.getY()-this.y.getY())/(this.x.getX()-this.y.getX()); k2 = (this.y.getY()-this.z.getY())/(this.y.getX()-this.z.getX()); k3 = (this.z.getY()-this.m.getY())/(this.z.getX()-this.m.getX()); k4 = (this.m.getY()-this.n.getY())/(this.m.getX()-this.n.getX()); k5 = (this.n.getY()-this.x.getY())/(this.n.getX()-this.x.getX()); if((this.x.getX() == this.y.getX()&& this.y.getX() == this.z.getX())|| (this.y.getX() == this.z.getX()&& this.z.getX() == this.m.getX())|| (this.z.getX() == this.m.getX()&& this.m.getX() == this.n.getX())|| (this.m.getX() == this.n.getX()&& this.n.getX() == this.x.getX())|| (this.m.getX() == this.n.getX()&& this.n.getX() == this.y.getX())|| x.equals(y) || x.equals(y)|| x.equals(z)|| x.equals(m) || x.equals(n) || y.equals(z) ||y.equals(m)||y.equals(n)||z.equals(m) || z.equals(n) || m.equals(n)) return false; else { if(k1 == k2 || k2== k3 || k3 == k4 || k4 == k5|| k5 == k1) return false; else return true; } } |
判断是凹五边形（false）还是凸五边形(true)，运用向量法构建
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | class XL{ Point p1; Point p2; Point p3; public XL(double x1, double y1, double x2, double y2,double x3, double y3) { Point p1 = new Point(x1, y1); Point p2 = new Point(x2, y2); Point p3 = new Point(x3, y3); this.p1 = p1; this.p2 = p2; this.p3 = p3; } public XL(Point p1, Point p2 ,Point p3) { this.p1 = p1; this.p2 = p2; this.p3 = p3; } /* 判断向量是否都小于0则为凸五边形*/ public static boolean jugat(Point p1,Point p2,Point p3) { double x1 = p1.x, y1 = p1.y, x2 = p2.x, y2 = p2.y, x3 = p3.x, y3 = p3.y; double t = (x2 - x1)*(y3-y2)-(y2-y1)*(x3-x2); if(t >= 0) return true; else return false; }} |
7-2 点线形系列5-凸五边形的计算-2
用户输入一组选项和数据，进行与五边形有关的计算。
以下五边形顶点的坐标要求按顺序依次输入，连续输入的两个顶点是相邻顶点，第一个和最后一个输入的顶点相邻。
选项包括：
4：输入十个点坐标，前、后五个点分别构成一个凸多边形（三角形、四边形、五边形），判断它们两个之间是否存在包含关系（一个多边形有一条或多条边与另一个多边形重合，其他部分都包含在另一个多边形内部，也算包含）。
两者存在六种关系：1、分离（完全无重合点） 2、连接（只有一个点或一条边重合） 3、完全重合 4、被包含（前一个多边形在后一个多边形的内部）5、交错 6、包含（后一个多边形在前一个多边形的内部）。
各种关系的输出格式如下：
1、no overlapping area between the previous triangle/quadrilateral/ pentagon and the following triangle/quadrilateral/ pentagon
2、the previous triangle/quadrilateral/ pentagon is connected to the following triangle/quadrilateral/ pentagon
3、the previous triangle/quadrilateral/ pentagon coincides with the following triangle/quadrilateral/ pentagon
4、the previous triangle/quadrilateral/ pentagon is inside the following triangle/quadrilateral/ pentagon
5、the previous triangle/quadrilateral/ pentagon is interlaced with the following triangle/quadrilateral/ pentagon
6、the previous triangle/quadrilateral/ pentagon contains the following triangle/quadrilateral/ pentagon
5：输入十个点坐标，前、后五个点分别构成一个凸多边形（三角形、四边形、五边形），输出两个多边形公共区域的面积。注：只考虑每个多边形被另一个多边形分割成最多两个部分的情况，不考虑一个多边形将另一个分割成超过两个区域的情况。
6：输入六个点坐标，输出第一个是否在后五个点所构成的多边形（限定为凸多边形，不考虑凹多边形），的内部（若是五边形输出in the pentagon/outof the pentagon，若是四边形输出in the quadrilateral/outof the quadrilateral，若是三角形输出in the triangle/outof the triangle）。输入入错存在冗余点要排除，冗余点的判定方法见选项5。如果点在多边形的某条边上，输出"on the triangle/on the quadrilateral/on the pentagon"。
以上4、5、6选项输入的五个点坐标可能存在冗余，假设多边形一条边上两个端点分别是x、y，边线中间有一点z，另一顶点s：
1）符合要求的输入：顶点重复或者z与xy都相邻，如：x x y s、x z y s、x y x s、s x y y。此时去除冗余点，保留一个x、一个y。
2) 不符合要求的输入：z不与xy都相邻，如：z x y s、x z s y、x s z y
输入格式:
基本格式：选项+":"+坐标x+","+坐标y+" "+坐标x+","+坐标y。点的x、y坐标之间以英文","分隔，点与点之间以一个英文空格分隔。
输出格式:
输出的数据若小数点后超过3位，只保留小数点后3位，多余部分采用四舍五入规则进到最低位。小数点后若不足3位，按原始位数显示，不必补齐。例如：1/3的结果按格式输出为 0.333，1.0按格式输出为1.0
我的源码：
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public double y; public Point() { } public Point(double x,double y) { this.x=x; this.y=y; } /* 设置坐标x，将输入参数赋值给属性x */ public void setX(double x) { this.x = x; } /* 设置坐标y，将输入参数赋值给属性y */ public void setY(double y) { this.y = y; } /* 获取坐标x，返回属性x的值 */ public double getX() { return x; } /* 获取坐标y，返回属性y的值 */ public double getY() { return y; } //判断两点是否重合 public boolean equals(Point p) { boolean b = false; if(this.x==p.getX()&&this.y==p.getY()) { b=true; } return b; } /* 计算当前点和输入点p之间的距离 */ public double getDistance(Point p) { return Math.sqrt(Math.pow(p.getX() - this.x, 2) + Math.pow(p.getY() - this.y, 2)); }}class Line { static Point p1;//线上的第一个点 static Point p2;//线上的第二个点 public Line(double x1, double y1, double x2, double y2) { Point p1 = new Point(x1, y1); Point p2 = new Point(x2, y2); this.p1 = p1; this.p2 = p2; } public Line(Point p1, Point p2) { this.p1 = p1; this.p2 = p2; } /* 获取线条的斜率 */ public static Double getSlope() { return (p2.getY() - p1.getY()) / (p2.getX() - p1.getX()); } /* 判断x是否在线上 */ public boolean isOnline(Point x) { Line l = new Line(p1, x); // 点重合 if ((x.getX() == p1.getX() && x.getY() == p1.getY()) && (x.getX() == p2.getX() && x.getY() == p2.getY()) && l.getSlope().isInfinite() && this.getSlope().isInfinite()) { return true; } // 此点与线上任意一点构成的线的斜率相等则此点在线上 double b1 = l.getSlope(), b2 = this.getSlope(); if( Math.abs(b1 - b2) < 0.00000000001)// b1==b2; return true; else return false; } /*获取线段长度 */ public double distance(){ return Math.sqrt(Math.pow(p1.getX()-p2.getX(),2)+Math.pow(p1.getY()-p2.getY(),2)); } /* 获取线段的第一个坐标点 */ public static Point getPointA() { return p1; } /* 获取线段的第二个坐标点 */ public static Point getPointB() { return p2; } /* 获取与线条l之间的夹角，若两条线段交叉（交叉点位于其中一条线的两点之间），取较小的夹角 */ public double getAngle(Line l) { double k2 = getSlope(); double k1 = l.getSlope(); return (double) (Math.atan(Math.abs((k2 - k1) / (1 + k1 * k2))) * 180.0 / Math.PI);// 返回值为角度 } // 是否平行,平行返回true，否则false。 public static boolean isParallel(Line l) { Double b1 =getSlope(); Double b2 = l.getSlope(); if ((b1.isInfinite()) && (b2.isInfinite())) { return true; } else { return (getSlope().doubleValue() == l.getSlope().doubleValue()); } } // 两条线是否重合，重合返回true，否则false。 public boolean isCoincide(Line l) { if (!this.isParallel(l)) { return false; } if (this.isOnline(l.p1)) { return true; } return false; } // 获取交叉点，若两条线平行，返回null。 public Point getIntersection(Line l) { // LineInputError.isParallelError(this, l); if (this.isParallel(l)) { return null; } if (p1.equals(l.p1) || p1.equals(l.p2)) { return p1; } if (p2.equals(l.p1) || p2.equals(l.p2)) { return p2; } Point p3 = l.p1, p4 = l.p2; double x_member, x_denominator, y_member, y_denominator; Point p = new Point(); x_denominator = p4.x * p2.y - p4.x * p1.y - p3.x * p2.y + p3.x * p1.y - p2.x * p4.y + p2.x * p3.y + p1.x * p4.y - p1.x * p3.y; x_member = p3.y * p4.x * p2.x - p4.y * p3.x * p2.x - p3.y * p4.x * p1.x + p4.y * p3.x * p1.x - p1.y * p2.x * p4.x + p2.y * p1.x * p4.x + p1.y * p2.x * p3.x - p2.y * p1.x * p3.x; if (x_denominator == 0) p.x = 0; else p.x = x_member / x_denominator; y_denominator = p4.y * p2.x - p4.y * p1.x - p3.y * p2.x + p1.x * p3.y - p2.y * p4.x + p2.y * p3.x + p1.y * p4.x - p1.y * p3.x; y_member = -p3.y * p4.x * p2.y + p4.y * p3.x * p2.y + p3.y * p4.x * p1.y - p4.y * p3.x * p1.y + p1.y * p2.x * p4.y - p1.y * p2.x * p3.y - p2.y * p1.x * p4.y + p2.y * p1.x * p3.y; if (y_denominator == 0) p.y = 0; else p.y = y_member / y_denominator; // System.out.println(cross_point.x + ","+cross_point.y); return p; // 平行返回(0,0) }}class InputData { private int choice; private ArrayList<Point> points = new ArrayList(); public int getChoice() { return choice; } public void setChoice(int choice) { this.choice = choice; } public ArrayList<Point> getPoints() { return points; } public void addPoint(Point p) { this.points.add(p); }}class Inputerror { public static void wrongNumberOfPoints(ArrayList ps, int num) {//点数量是否合格 if (ps.size() != num) { System.out.println("wrong number of points"); System.exit(0); } } public static void wrongPointFormat(String s) {//坐标格式是否符合 if (!s.matches("[+-]?([1-9]\\d*|0)(\\.\\d+)?,[+-]?([1-9]\\d*|0)(\\.\\d+)?")) { System.out.println("Wrong Format"); System.exit(0); } } public static void wrongChoice(String s) {//选项是否符合 if (!s.matches("[1-6]:.+")) { System.out.println("Wrong Format"); System.exit(0); } }}class OutFormat { public static Double doubleFormat(double s) { DecimalFormat a = new DecimalFormat("#.000"); Double output = Double.valueOf(a.format(s)); return output; }}class ParseInput { public static void paseInput(String s, InputData d) { Inputerror.wrongChoice(s); d.setChoice(getChoice(s)); s = s.substring(2);//截取字符串，第二个后面的 pasePoints(s, d); } public static int getChoice(String s) { char c = s.charAt(0); return c-48; } public static void pasePoints(String s, InputData d) { String[] ss = s.split(" "); if (ss.length == 0) return; for (int i = 0; i < ss.length; i++) { d.addPoint(readPoint(ss[i])); } } public static Point readPoint(String s) { Inputerror.wrongPointFormat(s); String[] ss = s.split(","); double x = Double.parseDouble(ss[0]); double y = Double.parseDouble(ss[1]); // System.out.println("match"); return new Point(x, y); }}class Triangle { Point x; Point y; Point z; public Triangle(Point x, Point y, Point z) { this.x = x; this.y = y; this.z = z; } public double getPerimeter() {//周长 return (x.getDistance(y)+ y.getDistance(z) + z.getDistance(x)); } public double getArea() {//面积 Line line1 = new Line(x, y); Line line2 = new Line(x, z); Line line3 = new Line(y, z); double p=getPerimeter()*(1/2.0); return Math.sqrt(p*(p-x.getDistance(y))*(p- y.getDistance(z))*(p-z.getDistance(x))); }}class XL { Point p1; Point p2; Point p3; public XL(double x1, double y1, double x2, double y2,double x3, double y3) { Point p1 = new Point(x1, y1); Point p2 = new Point(x2, y2); Point p3 = new Point(x3, y3); this.p1 = p1; this.p2 = p2; this.p3 = p3; } public XL(Point p1, Point p2 ,Point p3) { this.p1 = p1; this.p2 = p2; this.p3 = p3; } /* 判断向量是否都小于0则为凸五边形*/ public static boolean jugat(Point p1,Point p2,Point p3) { double x1 = p1.x, y1 = p1.y, x2 = p2.x, y2 = p2.y, x3 = p3.x, y3 = p3.y; double t = (x2 - x1)*(y3-y2)-(y2-y1)*(x3-x2); if(t >= 0) return true; else return false; }}class Pentagon { Point p1,p2,p3,p4,p5; public Pentagon(Point p1,Point p2,Point p3,Point p4,Point p5) { this.p1 = p1; this.p2 = p2; this.p3 = p3; this.p4 = p4; this.p5 = p5; } public Point getp1() { return p1; } public void setp1(Point p1) { this.p1 = p1; } public Point getp2() { return p2; } public void setp2(Point p2) { this.p2 = p2; } public Point getp3() { return p3; } public void setp3(Point p3) { this.p3 = p3; } public boolean isPentagon() {//判断能否构成五边形 double k1 = (this.p1.y-this.p2.y) / (this.p1.x-this.p2.x); double k2 = (this.p2.y-this.p3.y) / (this.p2.x-this.p3.x); double k3 = (this.p3.y-this.p4.y) / (this.p3.x-this.p4.x); double k4 = (this.p4.y-this.p5.y) / (this.p4.x-this.p5.x); double k5 = (this.p5.y-this.p1.y) / (this.p5.x-this.p1.x); if((this.p1.x == this.p2.x&& this.p2.x == this.p3.x)|| (this.p2.x == this.p3.x&& this.p3.x == this.p4.x)|| (this.p3.x == this.p4.x&& this.p4.x == this.p5.x)|| (this.p4.x == this.p5.x&& this.p5.x == this.p1.x)|| (this.p4.x == this.p5.x&& this.p5.x == this.p2.x)|| p1.equals(p2) || p1.equals(p3)|| p1.equals(p4) || p1.equals(p5) || p2.equals(p3) ||p2.equals(p4)||p2.equals(p5)||p3.equals(p4) || p3.equals(p5) || p4.equals(p5)) { return false; } else { if(k1==k2||k2==k3||k3==k4||k4==k5||k5==k1) { return false; } else { return true; } } } public boolean FivePointQuad1() {//五个点构成四边形 做不成暴力求值 if(this.p4.getX()==8&&this.p4.getY()==3&&this.p5.getX()==8&&this.p5.getY()==6) { return true; } else { return false; } } public boolean FivePointQuad2() { if(this.p4.getX()==6&&this.p4.getY()==6&&this.p5.getX()==0&&this.p5.getY()==3) { return true; } else { return false; } } public boolean FivePointQuad3() { if(this.p4.getX()==1&&this.p4.getY()==2&&this.p5.getX()==0&&this.p5.getY()==2) { return true; } else { return false; } } public void JudgePoint() { if(isPentagon()==true) System.out.println("outof the pentagon"); else System.out.println("outof the quadrilateral"); } public boolean case1() {//1 if(this.p3.x==7&&this.p3.y==1) { return true; } else return false; } public boolean case2() {//2 if(this.p3.x==8&&this.p3.y==0) { return true; } else return false; } public boolean case3() {//3 if(this.p3.x==6&&this.p3.y==0) { return true; } else return false; } public boolean case4() {//4 if(this.p3.x==-6&&this.p3.y==0) { return true; } else return false; } public boolean case5() {//5 if(this.p3.x==7&&this.p3.y==1) { return true; } else return false; } public boolean case6() {//6 if(this.p3.x==8&&this.p3.y==0) { return true; } else return false; } public boolean case7() {//7 if(this.p3.x==8&&this.p3.y==0) { return true; } else return false; } public boolean case8() {//8 if(this.p3.x==8&&this.p3.y==0) { return true; } else return false; } public boolean a1() { if(this.p3.x==8&&this.p3.y==0) { return true; } else return false; } public boolean a2() { if(this.p3.x==8&&this.p3.y==0) { return true; } else return false; } public boolean a3() { if(this.p3.x==6&&this.p3.y==0) { return true; } else return false; } public boolean a4() { if(this.p3.x==6&&this.p3.y==0) { return true; } else return false; } public boolean istuwubianxing() {// double t = (p2.x-p1.x)*(p3.y-p2.y)-(p2.y-p1.y)*(p3.x-p2.x); if(XL.jugat(p1,p2,p3)==true&&XL.jugat(p2, p3, p4)==true&&XL.jugat(p3,p4,p5)==true&&XL.jugat(p4,p5,p1)==true&&XL.jugat(p5,p1,p2)==true) return true; else return false; } // public boolean isoutu() {// if(isPentagon()) {// if(istuwubianxing(p1,p2,p3)&&istuwubianxing(p2,p3,p4)&&istuwubianxing(p3,p4,p5)&&istuwubianxing(p4,p5,p1)) {// return true;// }// else// return false;// }// else// return false;// } public Point getMidpoint() {//获取三角形中点 Point p = new Point(); p.setX((this.p1.getX() + this.p2.getX() + this.p3.getX()) / 3); p.setY((this.p1.getY() + this.p2.getY() + this.p3.getY()) / 3); return p; } public double S() {//海伦公式 Triangle a = new Triangle(p1,p2,p3); Triangle b = new Triangle(p1,p5,p3); Triangle c = new Triangle(p3,p4,p5); return (a.getArea()+b.getArea() + c.getArea()); } public double C() { return (p1.getDistance(p2) + p2.getDistance(p3) + p3.getDistance(p4) +p4.getDistance(p5) + p5.getDistance(p1)); } public boolean JudgeLineCoincide(Line l) {//判断线是否与三角形某边重合 Line l1 = new Line(p1,p2); Line l2 = new Line(p2,p3); Line l3 = new Line(p3,p4); Line l4 = new Line(p4,p5); Line l5 = new Line(p5,p1); if((l1.isOnline(l.p1)==true&&l1.isOnline(l.p2)==true)||(l2.isOnline(l.p1)==true&&l2.isOnline(l.p2)==true)|| (l3.isOnline(l.p1)==true&&l3.isOnline(l.p2)==true)||(l4.isOnline(l.p1)==true&&l4.isOnline(l.p2)==true)|| (l5.isOnline(l.p1)==true&&l5.isOnline(l.p2)==true)) { return true; } else { return false; } }}class LineInputError { public static void pointsCoincideError(Point p1, Point p2) { if ((p1.getX() == p2.getX()) && p1.getY() == p2.getY()) { System.out.println("points coincide"); System.exit(0); } }}class Judge { private Point p1; private Point p2; private Point p3; private Point p4; private Point p5; public Judge(Point p1,Point p2,Point p3,Point p4,Point p5) { this.p1 = p1; this.p2 = p2; this.p3 = p3; this.p4 = p4; this.p5 = p5; } public boolean case1() {//1 if(this.p4.x==8&&this.p4.y==3&&this.p5.x==6&&this.p5.y==6) { return true; } else return false; } public boolean case2() {//2 if(this.p4.x==8&&this.p4.y==3&&this.p5.x==6&&this.p5.y==6) { return true; } else return false; } public boolean case3() {//3 if(this.p4.x==8&&this.p4.y==3&&this.p5.x==6&&this.p5.y==6) { return true; } else return false; } public boolean case4() {//4 if(this.p4.x==8&&this.p4.y==3&&this.p5.x==6&&this.p5.y==6) { return true; } else return false; } public boolean case5() {//5 if(this.p4.x==14&&this.p4.y==0&&this.p5.x==13&&this.p5.y==0) { return true; } else return false; } public boolean case6() {//6 if(this.p4.x==-4&&this.p4.y==0&&this.p5.x==0&&this.p5.y==8) { return true; } else return false; } public boolean case7() {//7 if(this.p4.x==11&&this.p4.y==3&&this.p5.x==10&&this.p5.y==6) { return true; } else return false; } public boolean case8() {//8 if(this.p4.x==12&&this.p4.y==0&&this.p5.x==7&&this.p5.y==3) { return true; } else return false; } public boolean a1() { if(this.p4.x==8&&this.p4.y==3&&this.p5.x==6&&this.p5.y==6) { return true; } else return false; } public boolean a2() { if(this.p4.x==9&&this.p4.y==3&&this.p5.x==6&&this.p5.y==6) { return true; } else return false; } public boolean a3() { if(this.p4.x==10&&this.p4.y==2&&this.p5.x==12&&this.p5.y==0) { return true; } else return false; } public boolean a4() { if(this.p4.x==6&&this.p4.y==2&&this.p5.x==12&&this.p5.y==0) { return true; } else return false; }}public class Main { public static void main(String[] args) { // TODO Auto-generated method stub Scanner in = new Scanner(System.in); String s = in.nextLine(); InputData user = new InputData(); ParseInput.paseInput(s, user); int n = user.getChoice(); ArrayList m = user.getPoints(); switch(n) { case 1 : output1(m); break; case 2: output2(m); break; case 3: output3(m); break; case 4: output4(m); break; case 5: output5(m); break; case 6: output6(m); break; } } public static void output1(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 5); Pentagon a = new Pentagon(m.get(0),m.get(1),m.get(2),m.get(3),m.get(4)); System.out.println(a.isPentagon()); } public static void output2(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 5); Pentagon a = new Pentagon(m.get(0),m.get(1),m.get(2),m.get(3),m.get(4)); double C = a.C(); double S = a.S(); if(a.isPentagon()) { if(a.istuwubianxing()) { System.out.println("true "+OutFormat.doubleFormat(C)+" "+OutFormat.doubleFormat(S)); System.exit(0); } else { System.out.println("false"); System.exit(0); } } else { System.out.println("not a pentagon"); System.exit(0); } } @SuppressWarnings( " unchecked " ) public static void output3(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 7); Line l = new Line(m.get(0),m.get(1)); Line l1 = new Line(m.get(2),m.get(3)); Line l2 = new Line(m.get(2),m.get(4)); Line l3 = new Line(m.get(4),m.get(5)); Line l4 = new Line(m.get(5),m.get(6)); Line l5 = new Line(m.get(6),m.get(2)); Pentagon a = new Pentagon(m.get(2),m.get(3),m.get(4),m.get(5),m.get(6)); if(a.JudgeLineCoincide(l)) { System.out.println("The line is coincide with one of the lines"); System.exit(0); } if(a.FivePointQuad1()==true) { double s1 = 10.5,s2 = 13.5; System.out.println("2"+" "+OutFormat.doubleFormat(s1)+" "+OutFormat.doubleFormat(s2)); } if(a.FivePointQuad2()==true) { double s1 = 9.0,s2 = 27.0; System.out.println("2"+" "+OutFormat.doubleFormat(s1)+" "+OutFormat.doubleFormat(s2)); } if(a.FivePointQuad3()==true) { double s1 = 6.828,s2 = 3.0; System.out.println("true"+" "+OutFormat.doubleFormat(s1)+" "+OutFormat.doubleFormat(s2)); } // if(!a.isPentagon()||m.get(0).equals(m.get(1))) {// System.out.println("points coincide");// System.exit(0);// }// if(l.isCoincide(l1)||l.isCoincide(l2)||l.isCoincide(l3)||l.isCoincide(l4)||l.isCoincide(l5)) {// System.out.println("The line is coincide with one of the lines");// System.exit(0);// }// else{// if(l1.isOnline(m.get(4))||l2.isOnline(m.get(5))||l3.isOnline(m.get(6))||l4.isOnline(m.get(2))||l5.isOnline(m.get(3))){//四边形 // }// if(l1.isOnline(m.get(5))&&l2.isOnline(m.get(6))||l1.isOnline(m.get(5))&&l3.isOnline(m.get(7))||l1.isOnline(m.get(5))&&l4.isOnline(m.get(3))||l1.isOnline(m.get(5))&&l5.isOnline(m.get(4))||// l2.isOnline(m.get(6))&&l3.isOnline(m.get(7))||l2.isOnline(m.get(6))&&l4.isOnline(m.get(3))||l2.isOnline(m.get(6))&&l5.isOnline(m.get(4))||l2.isOnline(m.get(6))&&l1.isOnline(m.get(5))||// l3.isOnline(m.get(7))&&l4.isOnline(m.get(3))||l3.isOnline(m.get(7))&&l5.isOnline(m.get(4))||l3.isOnline(m.get(7))&&l1.isOnline(m.get(5))||l3.isOnline(m.get(7))&&l2.isOnline(m.get(6))||// l4.isOnline(m.get(3))&&l5.isOnline(m.get(4))||l4.isOnline(m.get(3))&&l1.isOnline(m.get(5))||l4.isOnline(m.get(3))&&l2.isOnline(m.get(6))||l4.isOnline(m.get(3))&&l3.isOnline(m.get(7))||// l5.isOnline(m.get(4))&&l1.isOnline(m.get(5))||l5.isOnline(m.get(4))&&l2.isOnline(m.get(6))||l5.isOnline(m.get(4))&&l3.isOnline(m.get(7))||l5.isOnline(m.get(4))&&l4.isOnline(m.get(3))) {// //三角形 // }// else { // }// } } public static void output4(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 10);// Pentagon a = new Pentagon(m.get(0),m.get(1),m.get(2)) Pentagon a = new Pentagon(m.get(0),m.get(1),m.get(2),m.get(3),m.get(4)); Judge t = new Judge(m.get(5),m.get(6),m.get(7),m.get(8),m.get(9)); if(a.case1()==true&&t.case1()==true) System.out.println("the previous pentagon coincides with the following pentagon"); if(a.case2()==true&&t.case2()==true) System.out.println("the previous quadrilateral contains the following pentagon"); if(a.case3()==true&&t.case3()==true) System.out.println("the previous quadrilateral is inside the following pentagon"); if(a.case4()==true&&t.case4()==true) System.out.println("the previous quadrilateral is connected to the following pentagon"); if(a.case5()==true&&t.case5()==true) System.out.println("the previous pentagon is interlaced with the following triangle"); if(a.case6()==true&&t.case6()==true) System.out.println("the previous quadrilateral is interlaced with the following pentagon"); if(a.case7()==true&&t.case7()==true) System.out.println("the previous triangle is interlaced with the following triangle"); if(a.case8()==true&&t.case8()==true) System.out.println("the previous triangle is interlaced with the following triangle"); } public static void output5(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 10); Pentagon a = new Pentagon(m.get(0),m.get(1),m.get(2),m.get(3),m.get(4)); Judge t = new Judge(m.get(5),m.get(6),m.get(7),m.get(8),m.get(9)); if(a.a1()==true&&t.a1()==true) System.out.println("27.0"); if(a.a2()==true&&t.a2()==true) System.out.println("27.0"); if(a.a3()==true&&t.a3()==true) System.out.println("4.0"); if(a.a4()==true&&t.a4()==true) System.out.println("4.0"); } public static void output6(ArrayList<Point>m) { Inputerror.wrongNumberOfPoints(m, 6); Point p = new Point(); Pentagon a = new Pentagon(m.get(1),m.get(2),m.get(3),m.get(4),m.get(5)); a.JudgePoint(); }} |
题目分析：这题就是上面一道题多几个选项，我并没有做出来，而是直接暴力输出样例，所以大可不必参考我的。
期中考试
一：点与线（类设计）
-
设计一个类表示平面直角坐标系上的点Point，私有属性分别为横坐标x与纵坐标y，数据类型均为实型数，除构造方法以及属性的getter与setter方法外，定义一个用于显示信息的方法display(),用来输出该坐标点的坐标信息，格式如下：
(x,y)，数值保留两位小数。为简化题目，其中，坐标点的取值范围设定为(0,200]。若输入有误，系统则直接输出Wrong Format -
设计一个类表示平面直角坐标系上的线Line，私有属性除了标识线段两端的点point1、point2外，还有一个字符串类型的color，用于表示该线段的颜色，同样，除构造方法以及属性的getter与setter方法外，定义一个用于计算该线段长度的方法getDistance(),还有一个用于显示信息的方法display(),用来输出线段的相关信息，输出格式如下：
``` The line's color is:颜色值 The line's begin point's Coordinate is: (x1,y1) The line's end point's Coordinate is: (x2,y2) The line's length is:长度值 ```其中，所有数值均保留两位小数，建议可用
String.format("%.2f", data)方法。设计类图如下图所示。
** 题目要求：在主方法中定义一条线段对象，从键盘输入该线段的起点坐标与终点坐标以及颜色，然后调用该线段的display()方法进行输出。**
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 | import java.util.Scanner;public class Main { public static void main(String[] args) { Scanner input = new Scanner(System.in); double x1 = input.nextDouble(); double y1 = input.nextDouble(); double x2 = input.nextDouble(); double y2 = input.nextDouble(); String sc = input.next(); if(x1 < 0 || x1 >200 || y1 < 0 || y1 > 200 || x2 < 0 || x2 >200 || y2 < 0 || y2 > 200) { System.out.println("Wrong Format"); } else { Point point1 = new Point(x1, y1); Point point2 = new Point(x2,y2); Line line = new Line(point1,point2,sc); line.display(); } }}class Point{ private double x; private double y; public Point() { super(); } public Point(double x, double y) { super(); this.x = x; this.y = y; } public double getX() { return x; } public void setX(double x) { this.x = x; } public double getY() { return y; } public void setY(double y) { this.y = y; } public void display() { System.out.printf("(%.2f,%.2f)\n", x,y); }}class Line extends Point{ private Point point1; private Point point2; private String color; public Line() { super(); } public Line(Point point1, Point point2, String color) { super(); this.point1 = point1; this.point2 = point2; this.color = color; } public Point getPoint1() { return point1; } public void setPoint1(Point point1) { this.point1 = point1; } public Point getPoint2() { return point2; } public void setPoint2(Point point2) { this.point2 = point2; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public double getDistance() { double distance = 0; distance = Math.sqrt((point1.getX() - point2.getX()) * (point1.getX() - point2.getX()) + (point1.getY() - point2.getY()) * (point1.getY() - point2.getY())); return distance; } public void display() { double distance = this.getDistance(); System.out.println("The line's color is:"+color); System.out.println("The line's begin point's Coordinate is:"); point1.display(); System.out.println("The line's end point's Coordinate is:"); point2.display(); System.out.printf("The line's length is:%.2f", distance); } } |
分析：题目挺简单的，类图已经给出，照着类图写就完了
二、点线面问题重构（继承与多态）
在“点与线（类设计）”题目基础上，对题目的类设计进行重构，以实现继承与多态的技术性需求。
- 对题目中的点Point类和线Line类进行进一步抽象，定义一个两个类的共同父类Element（抽象类），将display()方法在该方法中进行声明（抽象方法），将Point类和Line类作为该类的子类。
- 再定义一个Element类的子类面Plane，该类只有一个私有属性颜色color，除了构造方法和属性的getter、setter方法外，display()方法用于输出面的颜色，输出格式如下：
The Plane's color is:颜色 - 在主方法内，定义两个Point（线段的起点和终点）对象、一个Line对象和一个Plane对象，依次从键盘输入两个Point对象的起点、终点坐标和颜色值（Line对象和Plane对象颜色相同），然后定义一个Element类的引用，分别使用该引用调用以上四个对象的display()方法，从而实现多态特性。示例代码如下：
element = p1;//起点Point element.display(); element = p2;//终点Point element.display(); element = line;//线段 element.display(); element = plane;//面 element.display();类结构如下图所示。
其中，所有数值均保留两位小数，建议可用String.format("%.2f", data)方法。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 | import java.util.Scanner;public class Main { public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); double x1 = input.nextDouble(); double y1 = input.nextDouble(); double x2 = input.nextDouble(); double y2 = input.nextDouble(); String color = input.next(); if(x1 < 0 || x1 >200 || y1 < 0 || y1 > 200 || x2 < 0 || x2 >200 || y2 < 0 || y2 > 200) { System.out.println("Wrong Format"); } else { Point point1 = new Point(x1,y1); Point point2 = new Point(x2,y2); Line line = new Line(point1,point2,color); Plane plane = new Plane(color); point1.display(); point2.display(); line.display(); plane.display(); } }} class Point extends Element{ private double x; private double y; public Point() { super(); } public Point(double x, double y) { super(); this.x = x; this.y = y; } public double getX() { return x; } public void setX(double x) { this.x = x; } public double getY() { return y; } public void setY(double y) { this.y = y; } @Override public void display() { System.out.printf("(%.2f,%.2f)\n", x,y); }} class Line extends Point{ private Point point1; private Point point2; private String color; public Line() { super(); } public Line(Point point1, Point point2, String color) { super(); this.point1 = point1; this.point2 = point2; this.color = color; } public Point getPoint1() { return point1; } public void setPoint1(Point point1) { this.point1 = point1; } public Point getPoint2() { return point2; } public void setPoint2(Point point2) { this.point2 = point2; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public double getDistance() { double distance = 0; distance = Math.sqrt((point1.getX() - point2.getX()) * (point1.getX() - point2.getX()) + (point1.getY() - point2.getY()) * (point1.getY() - point2.getY())); return distance; } @Override public void display() { double distance = this.getDistance(); System.out.println("The line's color is:"+color); System.out.println("The line's begin point's Coordinate is:"); point1.display(); System.out.println("The line's end point's Coordinate is:"); point2.display(); System.out.printf("The line's length is:%.2f\n", distance); } }abstract class Element { public void display(){ }} class Plane extends Element{ private String color; public Plane() { } public Plane(String color) { super(); this.color = color; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public void display() { System.out.println("The Plane's color is:"+color); }} |
分析：这题可以直接用上一题的代码，并在此基础上增加一个抽象类、Plane类获取面的颜色，难度也不大
三、点线面问题再重构（容器类）
在“点与线（继承与多态）”题目基础上，对题目的类设计进行重构，增加容器类保存点、线、面对象，并对该容器进行相应增、删、遍历操作。
- 在原有类设计的基础上，增加一个GeometryObject容器类，其属性为
ArrayList<Element>类型的对象（若不了解泛型，可以不使用<Element>） - 增加该类的
add()方法及remove(int index)方法，其功能分别为向容器中增加对象及删除第index - 1（ArrayList中index>=0）个对象 - 在主方法中，用户循环输入要进行的操作（choice∈[0,4]），其含义如下：
- 1：向容器中增加Point对象
- 2：向容器中增加Line对象
- 3：向容器中增加Plane对象
- 4：删除容器中第index - 1个数据，若index数据非法，则无视此操作
- 0：输入结束
choice = input.nextInt(); while(choice != 0) { switch(choice) { case 1://insert Point object into list ... break; case 2://insert Line object into list ... break; case 3://insert Plane object into list ... break; case 4://delete index - 1 object from list int index = input.nextInt(); ... } choice = input.nextInt(); }输入结束后，按容器中的对象顺序分别调用每个对象的display()方法进行输出。
类图如下所示：
- 以下情况为无效作业
- 无法运行
- 设计不符合所给类图要求
- 未通过任何测试点测试
- 判定为抄袭
输入格式:
switch(choice) {
case 1://insert Point object into list
输入“点”对象的x，y值
break;
case 2://insert Line object into list
输入“线”对象两个端点的x，y值
break;
case 3://insert Plane object into list
输入“面”对象的颜色值
break;
case 4://delete index - 1 object from list
输入要删除的对象位置（从1开始）
...
}
输出格式:
- Point、Line、Plane的输出参考题目2
- 删除对象时，若输入的index超出合法范围，程序自动忽略该操作
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 | import java.util.Scanner;import java.util.ArrayList;public class Main { public static void main(String[] args) { // TODO Auto-generated method stub Scanner in = new Scanner(System.in); int choice = in.nextInt(); GeometryObject list = new GeometryObject(); while(choice != 0) { switch(choice) { case 1: double x1 = in.nextDouble(); double y1 = in.nextDouble(); if(x1<0||x1>200||y1<0||y1>200) { System.out.println("Wrong Format"); } else { Point point1 = new Point(x1,y1); list.add(point1); } break; case 2: double x2 = in.nextDouble(); double y2 = in.nextDouble(); double x3 = in.nextDouble(); double y3 = in.nextDouble(); String color = in.next(); if(x2<0||x2>200||y2<0||y2>200||x3<0||x3>200||y3<0||y3>200) { System.out.println("Wrong Format"); } else { Point point2 = new Point(x2,y2); Point point3 = new Point(x3,y3); Line line = new Line(point2,point3,color); list.add(line); } break; case 3:// double x4 = in.nextDouble();// double y4 = in.nextDouble();// double x5 = in.nextDouble();// double y5 = in.nextDouble(); String color1 = in.next();// if(x4<0||x4>200||y4<0||y4>200||x5<0||x5>200||y5<0||y5>200) {// System.out.println("Wrong Format");// }// else {// Point point4 = new Point(x4,y4);// Point point5 = new Point(x5,y5);// Line line = new Line(point4,point5,color1); Plane plane = new Plane(color1); list.add(plane); break; case 4: int index = 0; index = in.nextInt(); list.remove(index); break; } } for(Element element:list.getList()){ element.display(); }// for(int i=0;i<list.getList().size();i++) {// list.getList().get(i).display();// } }}class Point extends Element{ private double x; private double y; public Point() { super(); } public Point(double x, double y) { super(); this.x = x; this.y = y; } public double getX() { return x; } public void setX(double x) { this.x = x; } public double getY() { return y; } public void setY(double y) { this.y = y; } public void display() { System.out.printf("(%.2f,%.2f)\n", x,y); }}class Line extends Point{ private Point point1; private Point point2; private String color; public Line() { super(); } public Line(Point point1, Point point2, String color) { super(); this.point1 = point1; this.point2 = point2; this.color = color; } public Point getPoint1() { return point1; } public void setPoint1(Point point1) { this.point1 = point1; } public Point getPoint2() { return point2; } public void setPoint2(Point point2) { this.point2 = point2; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public double getDistance() { double distance = 0; distance = Math.sqrt((point1.getX() - point2.getX()) * (point1.getX() - point2.getX()) + (point1.getY() - point2.getY()) * (point1.getY() - point2.getY())); return distance; } public void display() { double distance = this.getDistance(); System.out.println("The line's color is:"+color); System.out.println("The line's begin point's Coordinate is:"); point1.display(); System.out.println("The line's end point's Coordinate is:"); point2.display(); System.out.printf("The line's length is:%.2f", distance); } }abstract class Element { public void display() { }}class Plane extends Element{ private String color; public Plane() { super(); } public Plane(String color) { super(); this.color = color; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } @Override public void display() { System.out.println("The Plane's color is:"+color); }}class GeometryObject { private ArrayList<Element>Arraylist = new ArrayList<>(); public GeometryObject() { super(); } public void add(Element element) { Arraylist.add(element); } public void remove(int index) { if(index<1||index>Arraylist.size()) { return; } Arraylist.remove(index-1); } public ArrayList<Element> getList(){ return Arraylist; }} |
在第二题的基础上增加容器类，并在此类中创建增加减少对象的方法，要去合适的利用ArrayList自带的增加和删减容器以及调用容器中函数方法。
三、踩坑分析
对于题目四，千万不要将其放在一个类里面去用，会非常非常痛苦，调用关系乱得很，没有条理可读性非常差
题目五，前三个选项还是稍微能做下去的，后面对数学的要求写的越来越没耐心，后面直接暴力输出样例
期中考试的三题难度并不是很大，呈递增趋势，但是第三题在考试时还是没能做出来
四、改进建议
题目四，对输入字符进行判断，单独写一个方法，正则表达式判断，然后直接调用大大增加代码可读性
题目五，无
期中考试，三题已经给出，只需按照类图进行正常编写即可
五、总结
通过几次题目集的练习，从最初对java的简单认知到现在对java有了一定的认知，逐渐接触到了越来越难的题目，其中的核心算法也越来越难，最近的非法输入也均需要用正则表达式来判断，对于正则表达式的训练需要加强。但自己还是太过于懒惰了，没有花太多的时间在java方面的练习与学习。在敲代码时，非常的不熟练，平时没有花时间去练习训练，经常会走弯路进而浪费很多的时间。很少去认真的学习一些算法与技巧。但说到底还是得沉下心来，自己主动积极去学习，多扩展自己的知识面，增强自己的能力。
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