第二次博客作业

前言
设计与分析
踩坑心得
改进建议
总结
前言：

我认为这几次pta的图形类设计的题目，难度系数对我来说还是比较高的，

主要不是难在对类的构造以及搭建上面，主要是难在一些测试点上，因为能力有限，

所以很多测试点不知道为什么没有通过，盲目的寻找很难发现自己究竟犯了什么错。

超星中链表类练习题目对我来说难度还是比较适中的，毕竟这是老师在课堂上讲过的题目，

而且主题框架已经跟我们打好了，特别是第2次双向链表的练习，

基本上主体框架已经不需要我们再去钻研，我们只需要考虑对前节点的连接和后节点的继承问题。

对于期中考试，我认为非常的失败，通过本次期中考试，我也发现了我自己很多的不足之处。

首先就是我的编码速度实在是太慢了，导致连题目都没有写完，然后我对题目的理解包括审题能力也有待提高，因为在第一题的时候看错了条件，导致浪费了大量时间，以至于影响了后面的编码心态。

前面所有的练习所涉及到的知识点主要包括继承，多态以及接口和一点点范型。

题量不大，但是都很精髓。

设计与分析：

题目集04----2

从提交列表可以明显看出，正常计算的测试点都能通过，但是格式错误一直没有办法解决，

这说明我在字符串的处理方面还是比较欠缺的，这是我的一大漏洞。

  1 import java.util.Scanner;
  2 
  3 public class Main {
  4     public static void main(String[] args) {
  5         Scanner input = new Scanner(System.in);
  6         String str;
  7         String[] str1;
  8         String[] str2;
  9         String[] str3;
 10         String[] str4;
 11         String[] str5;
 12         String[] str6;
 13         int t=0;
 14         str = input.nextLine();
 15         for(int i=0;i<str.length();i++) {
 16             if(str.charAt(i)==':') {
 17                 t=0;
 18                 break;
 19             }else {
 20                 t=1;
 21             }
 22         }
 23         if(t==1) {
 24             System.out.println("Wrong Format");
 25             System.exit(0);
 26         }
 27         str1=str.split(":");
 28         for(int i=0;i<str.length();i++) {
 29             if(str.charAt(i)==' ') {
 30                 t=0;
 31                 break;
 32             }else {
 33                 t=1;
 34             }
 35         }
 36         if(t==1) {
 37             System.out.println("Wrong Format");
 38             System.exit(0);
 39         }
 40         str2=str1[1].split(" ");
 41         str3=str2[0].split(",");
 42         str4=str2[1].split(",");
 43 
 44         double x1 = Double.parseDouble(str3[0]);
 45         double x2 = Double.parseDouble(str4[0]);
 46         double y1 = Double.parseDouble(str3[1]);
 47         double y2 = Double.parseDouble(str4[1]);
 48 
 49         if(str.charAt(0)=='1') {
 50             if(str2.length<=2) {
 51                 double k = (y1-y2)/(x1-x2);
 52                 if(x1==x2&&y1==y2) {
 53                     System.out.println("points coincide");
 54                 }else if(x1==x2) {
 55                     System.out.println("Slope does not exist");
 56                 }else {
 57                     System.out.println(k);
 58                 }
 59             }else {
 60                 System.out.println("wrong number of points");
 61             }
 62         }
 63         if(str.charAt(0)=='2') {
 64             if(str2.length==3) {
 65                 str5=str2[2].split(",");
 66                 double x3 = Double.parseDouble(str5[0]);
 67                 double y3 = Double.parseDouble(str5[1]);
 68                 double result =Math.abs((y2-y3)*x1+(x3-x2)*y1+x2*y3-y2*x3)/Math.sqrt((y2-y3)*(y2-y3) +(x2-x3)*(x2-x3));
 69                 if(x3==x2&&y3==y2) {
 70                     System.out.println("points coincide");
 71                 }else
 72                     System.out.println(result);
 73             }else {
 74                 System.out.println("wrong number of points");
 75             }
 76         }
 77         if(str.charAt(0)=='3') {
 78             if(str2.length==3) {
 79                 str5=str2[2].split(",");
 80                 double x3 = Double.parseDouble(str5[0]);
 81                 double y3 = Double.parseDouble(str5[1]);
 82                 double result =Math.abs((y2-y3)*x1+(x3-x2)*y1+x2*y3-y2*x3)/Math.sqrt((y2-y3)*(y2-y3) +(x2-x3)*(x2-x3));
 83                 if(x3==x2&&y3==y2||x1==x2&&y1==y2||x1==x3&&y1==y3) {
 84                     System.out.println("points coincide");
 85                 }
 86                 else if(result == 0){
 87                     System.out.println("true");
 88                 }
 89                 else
 90                     System.out.println("false");
 91             }
 92             else {
 93                 System.out.println("wrong number of points");
 94             }
 95         }
 96         if(str.charAt(0)=='4') {
 97             if(str2.length==4) {
 98                 str5=str2[2].split(",");
 99                 str6=str2[3].split(",");
100                 double x3 = Double.parseDouble(str5[0]);
101                 double y3 = Double.parseDouble(str5[1]);
102                 double x4 = Double.parseDouble(str6[0]);
103                 double y4 = Double.parseDouble(str6[1]);
104                 double k = (y1-y2)/(x1-x2);
105                 double k1 = (y4-y3)/(x4-x3);
106                 if((x1==x2&&y1==y2)||(x3==x4&&y3==y4)){
107                     System.out.println("points coincide");
108                 }
109                 else if(k==k1||x1==x2&&x2==x3&&x3==x4)
110                     System.out.println("true");
111                 else
112                     System.out.println("false");
113             }else {
114                 System.out.println("wrong number of points");
115             }
116         }
117         if(str.charAt(0)=='5') {
118             if(str2.length==4) {
119                 str5=str2[2].split(",");
120                 str6=str2[3].split(",");
121                 double x3 = Double.parseDouble(str5[0]);
122                 double y3 = Double.parseDouble(str5[1]);
123                 double x4 = Double.parseDouble(str6[0]);
124                 double y4 = Double.parseDouble(str6[1]);
125                 double max1;
126                 double max2;
127                 double max3;
128                 double max4;
129                 double min1;
130                 double min2;
131                 double min3;
132                 double min4;
133                 if(x1 > x2){
134                     max1 = x1;
135                     min1 = x2;
136                 }
137                 else{
138                     max1 = x2;
139                     min1 = x1;
140                 }
141 
142                 if(x3 > x4){
143                     max2 = x3;
144                     min2 = x4;
145                 }
146                 else{
147                     max2 = x4;
148                     min2 = x3;
149                 }
150 
151                 if(y1 > y2){
152                     max3 = y1;
153                     min3 = y2;
154                 }
155                 else{
156                     max3 = y2;
157                     min3 = y1;
158                 }
159 
160                 if(y3 > y4){
161                     max4 = y3;
162                     min4 = y4;
163                 }
164                 else{
165                     max4 = y4;
166                     min4 = y3;
167                 }
168 
169                 double k1 = (y1-y2)/(x1-x2);
170                 double k2 = (y4-y3)/(x4-x3);
171                 double b1 = y1-k1*x1;
172                 double b2 = y3-k2*x3;
173                 float xj = (float) ((float)-(b2-b1)/(k2-k1));
174                 float yj = (float) ((float)k1*xj+b1);
175                 if(x1==x2&&y1==y2||x3==x4&&y3==y4) {
176                     System.out.println("points coincide");
177                 }else if(k1==k2||x1==x2&&x2==x3&&x3==x4)
178                     System.out.println("is parallel lines,have no intersection point");
179                 else if(xj > min1 && xj < max1 && yj > min3 && yj < max3||xj > min2 && xj < max2 && yj > min4 && yj < max4)
180                     System.out.println(xj+","+yj+" true");
181                 else
182                     System.out.println(xj+","+yj+" false");
183             }
184             else {
185                 System.out.println("wrong number of points");
186             }
187         }
188     }
189 }

题目集04----3

该题跟上一题也是一样的，其余问题基本都能处理，但唯独格式错误一直无法解决，

这说明我在字符串处理方面还有很大的进步空间

  1 import java.text.DecimalFormat;
  2 import java.util.Scanner;
  3 
  4 public class  Main {
  5 
  6     public static void main(String[] args) {
  7         Scanner input =new Scanner(System.in);
  8         String str;
  9         String[] str1;
 10         String[] str2;
 11         String[] str3;
 12         String[] str4;
 13         String[] str5;
 14         String[] str6;
 15         int t=0;
 16         str=input.nextLine();
 17         for(int i=0;i<str.length();i++) {
 18             if(str.charAt(i)==':') {
 19                 t=0;
 20                 break;
 21             }else {
 22                 t=1;
 23             }
 24         }
 25         if(t==1) {
 26             System.out.println("Wrong Format");
 27             System.exit(0);
 28         }
 29         str1=str.split(":");
 30         str2=str1[1].split(" ");
 31         str3=str2[0].split(",");
 32         str4=str2[1].split(",");
 33 
 34         double x1 = Double.parseDouble(str3[0]);
 35         double y1 = Double.parseDouble(str3[1]);
 36         double x2 = Double.parseDouble(str4[0]);
 37         double y2 = Double.parseDouble(str4[1]);
 38         str5=str2[2].split(",");
 39         double x3 = Double.parseDouble(str5[0]);
 40         double y3 = Double.parseDouble(str5[1]);
 41         double result =Math.abs((y2-y3)*x1+(x3-x2)*y1+x2*y3-y2*x3)/Math.sqrt((y2-y3)*(y2-y3) +(x2-x3)*(x2-x3));
 42         if(result==0) {
 43             System.out.println("data error");
 44             System.exit(0);
 45         }
 46         if((x1==x2&&y1==y2)||(x1==x3&&y1==y3)||(x3==x2&&y3==y2)) {
 47             System.out.println("points coincide");
 48             System.exit(0);
 49         }
 50         double sqrt = Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
 51         double v = (x1 - x3) * (x1 - x3) + (y1 - y3) * (y1 - y3);
 52         if(str.charAt(0)=='1') {
 53             if(str2.length==3) {
 54                 if(str3.length==2&&str4.length==2&&str5.length==2) {
 55                     double l2 = Math.sqrt(v);
 56                     double l3 = Math.sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
 57                     if( sqrt + l2 > l3 && sqrt + l3 > l2 && l2 + l3 > sqrt) {
 58                         if(sqrt ==l2|| sqrt ==l3||l2==l3) {
 59                             if(sqrt ==l2&&l2==l3) {
 60                                 System.out.println("true true");
 61                             }else {
 62                                 System.out.println("true false");
 63                             }
 64                         }
 65                         else {
 66                             System.out.println("false false");
 67                         }
 68 
 69                     }else {
 70                         System.out.println("data error");
 71                     }
 72                 }else {
 73                     System.out.println("Wrong Format");
 74                 }
 75             }else {
 76                 System.out.println("wrong number of points");
 77             }
 78         }
 79         if(str.charAt(0)=='2') {
 80             if(str2.length==3) {
 81                 if(str3.length==2&&str4.length==2&&str5.length==2) {
 82                     double l2 = Math.sqrt(v);
 83                     double l3 = Math.sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
 84                     double c = (sqrt +l2+l3);
 85                     double p = (sqrt +l2+l3)/2;
 86                     double s = Math.sqrt(p*(p- sqrt)*(p-l2)*(p-l3));
 87                     double xj = (sqrt +l2+l3)/3;
 88                     double yj = (sqrt +l2+l3)/3;
 89                     String str_d = String.valueOf(xj);
 90                     for(int i=0;i<str_d.length();i++) {
 91                         if(str_d.charAt(i)=='.') {
 92                             break;
 93                         }
 94                     }
 95                     new DecimalFormat("0.000000").format(xj);
 96                     if( sqrt + l2 > l3 && sqrt + l3 > l2 && l2 + l3 > sqrt) {
 97                         System.out.println(c+" "+s+" "+xj+","+yj);
 98                     }else {
 99                         System.out.println("data error");
100                     }
101                 }else {
102                     System.out.println("Wrong Format");
103                 }
104             }else {
105                 System.out.println("wrong number of points");
106             }
107         }
108         if(str.charAt(0)=='3') {
109             if(str2.length==3) {
110                 if(str3.length==2&&str4.length==2&&str5.length==2) {
111                     double l2 = Math.sqrt(v);
112                     double l3 = Math.sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
113                     if( sqrt + l2 > l3 && sqrt + l3 > l2 && l2 + l3 > sqrt) {
114                         if((sqrt * sqrt +l2*l2-l3*l3)<1e-16||(sqrt * sqrt +l3*l3-l2*l2)<1e-16||(l2*l2+l3*l3- sqrt * sqrt)<1e-16) {
115                             System.out.println("false true false");
116                         } if((sqrt * sqrt +l2*l2<l3*l3)||(sqrt * sqrt +l3*l3<l2*l2)||(l2*l2+l3*l3< sqrt * sqrt)) {
117                             System.out.println("true false false");
118                         } if((sqrt * sqrt +l2*l2>l3*l3)&&(sqrt * sqrt +l3*l3>l2*l2)&&(l2*l2+l3*l3> sqrt * sqrt)) {
119                             System.out.println( "false false true");
120                         }
121                     }else {
122                         System.out.println("data error");
123                     }
124 
125                 }else {
126                     System.out.println("Wrong Format");
127                 }
128 
129             }else {
130                 System.out.println("wrong number of points");
131             }
132         }
133         if(str.charAt(0)=='4') {
134             if(str2.length==4) {
135                 str6=str2[3].split(",");
136                 double x4 = Double.parseDouble(str6[0]);
137                 double y4 = Double.parseDouble(str6[1]);
138                 double k = (y1-y2)/(x1-x2);
139                 double k1 = (y4-y3)/(x4-x3);
140                 if(x3 == x4 && y3 == y4){
141                     System.out.println("points coincide");
142                 }
143                 else if(k==k1)
144                     System.out.println("true");
145                 else
146                     System.out.println("false");
147             }else {
148                 System.out.println("wrong number of points");
149             }
150         }
151         if(str.charAt(0)=='5') {
152             if(str2.length==4) {
153                 str6=str2[3].split(",");
154                 double x4 = Double.parseDouble(str6[0]);
155                 double y4 = Double.parseDouble(str6[1]);
156                 double k1 = (y1-y2)/(x1-x2);
157                 double k2 = (y4-y3)/(x4-x3);
158                 double b1 = y1-k1*x1;
159                 double b2 = y3-k2*x3;
160                 double xj = -(b2-b1)/(k2-k1);
161                 double yj = k1*xj+b1;
162                 if(k1==k2)
163                     System.out.println("is parallel lines,have no intersection point");
164                 else if(yj==k1*xj+b1||yj==k2*xj+b2)
165                     System.out.println(xj+","+yj+" true");
166                 else
167                     System.out.println(xj+","+yj+" false");
168             }else {
169                 System.out.println("wrong number of points");
170             }
171         }
172     }
173 }

双向链表

  1 package LinkedList;
  2 
  3 import java.util.NoSuchElementException;
  4 public class DoubleLinkedList<E> implements DoubleLinkedListImpl<E> {
  5 
  6     private Node<E> head;//头结点，非第一个节点
  7 
  8     private Node<E> curr;//当前节点
  9 
 10     private Node<E> tail;//最后一个节点
 11 
 12     private int size;//当前链表节点数
 13 
 14 
 15     @Override
 16     public boolean isEmpty() {
 17         return this.size <= 0;
 18     }
 19 
 20     @Override
 21     public int getSize() {
 22         return this.size;
 23     }
 24 
 25     private Node node(int index) {
 26         if (index >= this.size)
 27             return null;
 28         int len = this.size;
 29         if (index < len) {
 30             if (index > len / 2) {
 31                 Node curr = tail;
 32                 int step = len - index - 1;
 33                 while (step-- > 0) {
 34                     curr = curr.previous;
 35                 }
 36                 return curr;
 37             } else {
 38                 Node curr = head;
 39                 int step = index;
 40                 while (step-- > 0) {
 41                     curr = curr.next;
 42                 }
 43                 return curr;
 44             }
 45         }
 46         return null;
 47     }
 48     @Override
 49     public E getData(int index) {
 50         Node node = node(index);
 51         if (node != null)
 52             return (E) node.data;
 53         else {
 54             try {
 55                 throw new NullPointerException();
 56             } catch (NullPointerException e) {
 57                 System.out.println("Null：no such element");
 58                 return null;
 59             }
 60 
 61         }
 62     }
 63 
 64     @Override
 65     public void remove() {
 66         final Node<E> l = tail;
 67         if (l == null)
 68             throw new NoSuchElementException();
 69         return ;
 70 
 71     }
 72 
 73     @Override
 74     public void remove(int index) {
 75 
 76     }
 77 
 78     //链表头部添加元素
 79     public void addFirst(E element) {
 80         Node node = new Node(null,null,element);    //节点对象
 81         node.next = this.head;
 82         this.head = node;
 83         this.size++;
 84     }
 85 
 86     @Override
 87     public void add(int index, E theElement) {
 88         if (index == 0) {
 89             this.addFirst(theElement);
 90             return;
 91         }
 92 
 93         Node preNode = this.head;
 94         for (int i = 0; i < index - 1; i++) {
 95             preNode = preNode.next;
 96         }
 97 
 98         Node node = new Node(null,null,theElement);
 99         node.next = preNode.next;
100         preNode.next = node;
101         this.size++;
102     }
103 
104     @Override
105     public void add(E data) {
106         if (head == null) {
107             Node node = new Node(null, null, data);
108             head = node;
109             tail = node;
110         } else {
111             Node node = new Node(null, tail, data);
112             tail.next = node;
113             tail = node;
114         }
115         this.size++;
116     }
117 
118     @Override
119     public void printList() {
120         int count = this.size;
121         Node curr = head;
122         System.out.print("打印链表元素：");
123 
124         while (count-- > 0) {
125             System.out.print("  " + curr.data);
126             curr = curr.next;
127         }
128 
129         System.out.println();
130 
131     }
132 
133     @Override
134     public E getFirst() {
135         final Node<E> f = head;
136         if (f == null)
137             throw new NoSuchElementException();
138         return f.data;
139 
140     }
141 
142     @Override
143     public E getLast() {
144         final Node<E> l = tail;
145         if (tail == null)
146             throw new NoSuchElementException();
147         return l.data;
148 
149     }
150 }
151 
152 package LinkedList;
153 
154 public interface DoubleLinkedListImpl<E> {
155 
156     /**
157      * 判断链表是否为空
158      *
159      * @return
160      */
161 
162     public boolean isEmpty();
163 
164 
165     /**
166      * 获取当前链表节点数量
167      *
168      * @return 节点数
169      */
170 
171     public int getSize();
172 
173 
174     /**
175      * 获取链表中第index个位置的节点的data值
176      *
177      * @param index：节点在链表中的位置
178      * @return：返回该节点的data值
179      */
180 
181     public E getData(int index);
182 
183 
184     /**
185      * 删除链表最后一个节点
186      */
187 
188     public void remove();
189 
190 
191     /**
192      * 删除链表中第index位置的节点
193      *
194      * @param index：节点在链表中的位置
195      */
196 
197     public void remove(int index);
198 
199 
200     /**
201      * 在链表的第index个位置之前插入一个节点，值为theElement，index∈[1,size]
202      *
203      * @param index:插入节点在链表中的位置
204      * @param theElement：新插入节点的data值
205      */
206 
207     public void add(int index, E theElement);
208 
209 
210     /**
211      * 在链表尾插入节点，插入节点data值为element
212      *
213      * @param element
214      */
215 
216     public void add(E element);
217 
218 
219     /**
220      * 输出链表
221      */
222 
223     public void printList();
224 
225 
226     /**
227      * 获取第一个节点的data值
228      *
229      * @return
230      */
231 
232     public E getFirst();
233 
234 
235     /**
236      * 获取链表最后一个节点的data值
237      *
238      * @return
239      */
240 
241     public E getLast();
242 
243 }
244 
245 package LinkedList;
246 
247 public class Node<E> {
248 
249     public E data;//数据域，类型为泛型E
250 
251     public Node<E> next;//后继引用（指针）
252 
253     public Node<E> previous;//前驱引用（指针）
254 
255     public Node(Node next, Node previous, E data) {
256         super();
257         this.next = next;
258         this.previous = previous;
259         this.data = data;
260     }
261 
262 
263 }

期中考试----1

  1 import java.lang.*;
  2 import java.util.*;
  3 import java.util.Scanner;
  4 public class Main {
  5     public static void main(String[] args) {
  6         Scanner in = new Scanner(System.in);
  7         double x1 = in.nextDouble();
  8         double y1 = in.nextDouble();
  9         double x2 = in.nextDouble();
 10         double y2 = in.nextDouble();
 11         String color = in.next();
 12         if(x1<=0||x1>200||y1<=0||y1>200||x2<=0||x2>200||y2<=0||y2>200){
 13             System.out.println("Wrong Format");
 14         }
 15         else{
 16             Point point1 = new Point(x1,y1);
 17             Point point2 = new Point(x2,y2);
 18             Line b = new Line(point1,point2,color);
 19             b.display();
 20         }
 21     }
 22 }
 23 class Point{//表示平面直角坐标系上的点
 24     private  double x;
 25     private  double y;
 26 
 27     Point(){
 28 
 29     }
 30 
 31     Point(double x,double y){
 32         this.x = x;
 33         this.y = y;
 34     }
 35 
 36     double getX(){//构造方法以及属性
 37         return this.x;
 38     }
 39 
 40     void setX(double x){//构造方法以及属性
 41         this.x = x;
 42     }
 43 
 44     double getY(){//构造方法以及属性
 45         return this.y;
 46     }
 47 
 48     void setY(double y){//构造方法以及属性
 49         this.y = y;
 50     }
 51 
 52     void display(){//用于显示信息的方法
 53         System.out.println("The line's begin point's Coordinate is:"+"("+String.format("%.2f",x)+","+String.format("%.2f",y)+")");
 54     }
 55 
 56 }
 57 
 58 class Line{
 59     private Point point1;
 60     private Point point2;
 61     private String color;
 62 
 63     Line(){
 64 
 65     }
 66 
 67     Line(Point point1,Point point2,String color){
 68         this.point1 = point1;
 69         this.point2 = point2;
 70         this.color = color;
 71 
 72     }
 73 
 74     Point getPoint1(){
 75         return this.point1;
 76     }
 77 
 78     void setPoint1(Point point1){
 79         this.point1 = point1;
 80     }
 81 
 82     Point getPoint2(){
 83         return this.point2;
 84     }
 85 
 86     void setPoint2(Point point2){
 87         this.point2 = point2;
 88     }
 89 
 90     String getColor(){
 91         return this.color;
 92     }
 93 
 94     void setColor(String color){
 95         this.color = color;
 96     }
 97 
 98     double getDistance(){
 99         return Math.sqrt(Math.abs((point1.getX() - point2.getX())* (point1.getX() - point2.getX())+(point1.getY() - point2.getY())* (point1.getY() - point2.getY())));
100     }
101 
102     void display(){
103         System.out.println("The line's color is:"+color);
104         System.out.println("The line's begin point's Coordinate is:");
105         System.out.println("("+String.format("%.2f",point1.getX())+","+String.format("%.2f",point1.getY())+")");
106         System.out.println("The line's end point's Coordinate is:");
107         System.out.println("("+String.format("%.2f",point2.getX())+","+String.format("%.2f",point2.getY())+")");
108         System.out.println("The line's length is:"+String.format("%.2f",getDistance()));
109     }
110 
111 }

期中考试----2

  1 import java.lang.*;
  2 import java.util.Scanner;
  3 public class Main {
  4     public static void main(String[] args) {
  5         Scanner in = new Scanner(System.in);
  6         double x1 = in.nextDouble();
  7         double y1 = in.nextDouble();
  8         double x2 = in.nextDouble();
  9         double y2 = in.nextDouble();
 10         String color = in.next();
 11         if(x1<=0||x1>200||y1<=0||y1>200||x2<=0||x2>200||y2<=0||y2>200){
 12             System.out.println("Wrong Format");
 13         }
 14         else{
 15             Point point1 = new Point(x1,y1);
 16             Point point2 = new Point(x2,y2);
 17             Line line = new Line(point1,point2,color);
 18             Plane plane = new Plane(color);
 19             Element element = new Element();
 20 
 21             element = point1;//起点Point
 22             element.display();
 23 
 24             element = point2;//终点Point
 25             element.display();
 26 
 27             element = line;//线段
 28             element.display();
 29 
 30             element = plane;//面
 31             element.display();
 32 
 33         }
 34     }
 35 }
 36 
 37 class Element{
 38 
 39     void display(){
 40 
 41     }
 42 
 43 }
 44 class Plane extends Element{
 45     private String color;
 46 
 47     Plane(){
 48 
 49     }
 50 
 51     Plane(String color){
 52         this.color = color;
 53     }
 54 
 55     String getColor(){
 56         return this.color;
 57     }
 58 
 59     void setColor(String color){
 60         this.color = color;
 61     }
 62 
 63     void display(){
 64         System.out.println("The Plane's color is:"+color);
 65     }
 66 }
 67 
 68 class Point extends Element{//表示平面直角坐标系上的点
 69     private  double x;
 70     private  double y;
 71 
 72     Point(){
 73 
 74     }
 75 
 76     Point(double x,double y){
 77         this.x = x;
 78         this.y = y;
 79     }
 80 
 81     double getX(){//构造方法以及属性
 82         return this.x;
 83     }
 84 
 85     void setX(double x){//构造方法以及属性
 86         this.x = x;
 87     }
 88 
 89     double getY(){//构造方法以及属性
 90         return this.y;
 91     }
 92 
 93     void setY(double y){//构造方法以及属性
 94         this.y = y;
 95     }
 96 
 97     void display(){//用于显示信息的方法
 98         System.out.println("("+String.format("%.2f",x)+","+String.format("%.2f",y)+")");
 99     }
100 
101 }
102 
103 class Line extends  Element{
104     private Point point1;
105     private Point point2;
106     private String color;
107 
108     Line(){
109 
110     }
111 
112     Line(Point point1,Point point2,String color){
113         this.point1 = point1;
114         this.point2 = point2;
115         this.color = color;
116 
117     }
118 
119     Point getPoint1(){
120         return this.point1;
121     }
122 
123     void setPoint1(Point point1){
124         this.point1 = point1;
125     }
126 
127     Point getPoint2(){
128         return this.point2;
129     }
130 
131     void setPoint2(Point point2){
132         this.point2 = point2;
133     }
134 
135     String getColor(){
136         return this.color;
137     }
138 
139     void setColor(String color){
140         this.color = color;
141     }
142 
143     double getDistance(){
144         return Math.sqrt(Math.abs((point1.getX() - point2.getX())* (point1.getX() - point2.getX())+(point1.getY() - point2.getY())* (point1.getY() - point2.getY())));
145     }
146 
147     void display(){
148         System.out.println("The line's color is:"+color);
149         System.out.println("The line's begin point's Coordinate is:");
150         System.out.println("("+String.format("%.2f",point1.getX())+","+String.format("%.2f",point1.getY())+")");
151         System.out.println("The line's end point's Coordinate is:");
152         System.out.println("("+String.format("%.2f",point2.getX())+","+String.format("%.2f",point2.getY())+")");
153         System.out.println("The line's length is:"+String.format("%.2f",getDistance()));
154     }
155 
156 }