第二次考试函数编程

05类

函数题1-10 编程题 1-10

##1
  public int sum(double...values)
        //接受若干个，最后一个为valus


##2
//构造器条件判断
   if(x > 0&& y > 0&&z > 0&&p > 0)
   else
   
		   
##3
/数字转化成字符串后返回
 double area=this.width*this.height;
        return String.format("%.2f", area);
		
		System.out.println(r+" "+String.format("%.2f",h)+" "+mon);
		
##4最大公约数
//比较绝对值
public int gys(int a, int b)
    {
        int n = Math.min(Math.abs(a), Math.abs(b));
        int m = Math.max(Math.abs(a), Math.abs(b));
        int t;
        while(n != 0)
        {
            t = m % n;
            m = n;
            n = t;
        }
        return m;
    }
	
	
	
##5重写toString

@Override
    public String toString() {
        return "("+x+","+y+")";
    }
	

##5 
 return new Point(x, y);
        //多个值需要通过类或数组返回
		
 Point p = new Point(cin.nextInt(), cin.nextInt());
            //可以直接这样输入赋值合并
			

##6
double A=radius*radius*Math.PI;
        return (float)((Math.round(A * 100)) / 100.0);


##7
//字符串转化为字符数组
String str=sc.next();
            char[] ch=str.toCharArray();
			
			

06 继承多态接口

函数题1-10 编程题 1-8

##1类对象是否相等

public boolean equals(Object o) {
    if (this == o) return true; // 同一对象
    if (o == null || getClass() != o.getClass()) return false; // 空或不同类
    Point point = (Point) o; // 类型转换
    return this.xPos == point.xPos && this.yPos == point.yPos; // 属性比较
}

##2compare接口

class Octagon implements Comparable<Octagon>,Cloneable {
    @Override
    public int compareTo(Octagon o) {
        if (this.side > o.getSide())
            return 1;
        else if (this.side < o.getSide())
            return -1;
        else
            return 0;
    }
}
@Override
    protected Object clone() {
        return this;
    }
	
	
##3super
//子类重写的方法中调用父类方法

 return 2 * super.area() + length() * z;
//        调用的是父类 Rect 中定义的 area() 方法


##4
  USB[] usbs=new USB[2];
        usbs[0]=new UPan();
        usbs[1]=new Mouse();
        for(int i=0;i<usbs.length;i++)
        {
            usbs[i].work();
            usbs[i].stop();
        }

##5答答租车系统
import java.util.Scanner;
class Car {
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int id;
    public int rent;
    public String name;

    public int getLoadr() {
        return loadr;
    }

    public void setLoadr(int loadr) {
        this.loadr = loadr;
    }

    public int getRent() {
        return rent;
    }

    public void setRent(int rent) {
        this.rent = rent;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getLoadh() {
        return loadh;
    }

    public void setLoadh(double loadh) {
        this.loadh = loadh;
    }


    public int loadr;
    public double loadh;

    public Car(int id, String name,int loadr, double loadh,int rent ) {
       this.id=id;
        this.name = name;
        this.rent = rent;
        this.loadr = loadr;
        this.loadh = loadh;
    }
}
public class Main
{
    public static void main(String args[])
    {
        Car[] car = new Car[11];

        car[1] = new Car(1, "A", 5, 0, 800);
        car[2] = new Car(2, "B", 5, 0, 400);
        car[3] = new Car(3, "C", 5, 0, 800);
        car[4] = new Car(4, "D", 51, 0, 1300);
        car[5] = new Car(5, "E", 55, 0, 1500);
        car[6] = new Car(6, "F", 5, 0.45, 500);
        car[7] = new Car(7, "G", 5, 2.0, 450);
        car[8] = new Car(8, "H", 0, 3, 200);
        car[9] = new Car(9, "I", 0, 25, 1500);
        car[10] = new Car(10, "J", 0, 35, 2000);
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        if(n==1)
        {
            int num=sc.nextInt();
            int r=0;
            double h=0.00;
            int mon=0;
            for(int  i=1;i<=num;i++)
            {
                int idd=sc.nextInt();
                int day= sc.nextInt();
                r+=car[idd].getLoadr()*day;
                h+=car[idd].getLoadh()*day;
                mon+=car[idd].getRent()*day;

            }
            System.out.println(r+" "+String.format("%.2f",h)+" "+mon);
        }
        else
          System.out.println("0 0.00 0");


    }
}

##6 赋值一定记得判断0
public Rectangle(double l, double h) {
        if (l > 0 && h > 0) {
            // 二者均大于0，才能构成图形
            this.l = l;
            this.h = h;
        }
    }


## 7 判断类类型
 if (A[i] instanceof Rectangle) {
                System.out.print("Rectangle ");
                System.out.print(A[i].toString());
            }
			
##8
 ArrayList<PersonOverride> ap=new ArrayList<PersonOverride>();
        for (int i=0;i<n1;i++){
            ap.add(new PersonOverride());
        }
        int n2= sc.nextInt();
        // sc.nextLine();
        for (int i=0;i<n2;i++){
            f=true;
            PersonOverride a=new PersonOverride(sc.next(),sc.nextInt(), sc.nextBoolean());
            // sc.nextLine();
            for (PersonOverride aa:ap) {
                if (aa.equals(a)){
                    f=false;
                    break;
                }
            }
            if (f)ap.add(a);
        }
        for(PersonOverride a:ap){
            System.out.println(a.toString());
        }
        System.out.println(ap.size()-n1);
        System.out.println(Arrays.toString(PersonOverride.class.getConstructors()));
        //输出构造器，它返回的是一个 Constructor 类型的数组，所以用Arrays.toString()
		
## 8输出
                System.out.println("The area of " + c.toString() + " is " + String.format("%.2f",c.getArea()));
				

07 异常

函数题 1-6 编程题1-6

## 1

 public Integer push(Integer item) throws FullStackException {
 if(this.size() >= this.arrStack.length )throw new FullStackException();
 if (item == null)
 return null;
 this.arrStack[this.top] = item;
 this.top++;
 return item;          
}//如果item为null，则不入栈直接返回null。如果栈满，抛出`FullStackException`。


public Integer pop() throws EmptyStackException {
 if(this.empty()) throw new EmptyStackException();
 if (this.arrStack[top-1] == null)
 return null;
 this.top--;
 return this.arrStack[top];
    //pop返回的是弹出的元素，指向这个元素，但是因为peek不这么取所以相当于弹出
     }//出栈。如果栈空，抛出EmptyStackException。否则返回
 

public Integer peek() throws EmptyStackException {
        if(top == 0) throw new EmptyStackException();
        if (arrStack[top-1] == null) return null;
        return arrStack[top-1];
    }//获得栈顶元素。如果栈空，抛出EmptyStackException。
	

##2 自定义异常类

import java.util.*;
public class Main {

    public static void main(String[] args) {
        double s=0;
        Scanner sc=new Scanner(System.in);
        double r1,r2;
        r1=sc.nextDouble();
        r2=sc.nextDouble();
        Circle c1=new Circle(r1);
        
        try{
            s = c1.area();
            System.out.println(s);
           
        }
        catch (CircleException e){
            e.print();
        }
    }
}


class Circle{
    double r;
    public Circle(double r)
    {
        this.r=r;
    }
    double area()throws CircleException{
        if(this.r<0)
        {
            throw new CircleException(this.r);
            //throw实例化时不加s
        }
        return 3.14*r*r;
    }
}
//自定义异常类
class CircleException extends Exception{
    double r;
    public CircleException(double r)
    {
        this.r=r;
    }
    void print(){
        System.out.println("圆半径为"+this.r+"不合理");
    }
}

## 3
System.out.println(e.toString()); 和 System.out.println(e); 在 Java 中是等效的，都会自动调用对象的 toString() 方法。

## 3强制转化注意

else if (a.equals("cast")){
                // String  b = input.next();
                try {
                   Object str = new String("");
                    //必须用Object
                    System.out.println((Integer)(str));
                }catch (Exception e){
                    System.out.println(e);
                }

## 4 退出程序，数组输出
System.exit(0);
  System.out.println(Arrays.toString(a));
  

## 5 自定义异常(综合)
import java.util.*;
public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
       while (sc.hasNext()) {
           //这里有一个while循环
           if (!sc.next().equals("new")) {
               System.out.println("scanner closed");
               sc.close();
               break;
           }
           else {
               sc.nextLine();
               //要读空格
                String s = sc.nextLine();
                String[] s2 = s.split("\\s+");
                try {
                    Student stu = new Student();
                    stu.setName(s2[0]);
                    stu.addScore(Integer.parseInt(s2[1]));
                    System.out.println(stu);
                }
                catch (IllegalNameException|IllegalScoreException e)
                //只在最后一个加e
                {
                    System.out.println(e);
                } catch (Exception e) {
                    System.out.println("java.util.NoSuchElementException");
                }

            }

        }
    }
}
class Student{
    Student(){
        this.score = 0;
    };
    private String name;

    public int getScore() {
        return score;
    }
    public void setScore() {
        this.score=score;
    }
    public void addScore(int score) throws IllegalScoreException {
        if (this.score + score < 0||this.score + score > 100)
            throw new  IllegalScoreException(score);
        this.score = score;

    }

    public String getName() {
        return name;
    }

    public void setName(String name) throws IllegalNameException {
        if(name.charAt(0)>='0'&&name.charAt(0)<='9')
            throw new IllegalNameException(name);
        this.name = name;
    }

    private int score;

    @Override
    public String toString() {
        return "Student [name="+name+", score="+score+"]";
    }
}
class IllegalNameException extends Exception{

    String name;
    IllegalNameException(String name)
    {
        this.name=name;
    }
    public String toString()
    {
        return "IllegalNameException: the first char of name must not be digit, name="+name;
    }

}
class IllegalScoreException extends Exception{
    int score;
    IllegalScoreException(int score)
    {
        this.score=score;
    }
    public String toString()
            //继承的是父类，不用传参
    {
        return "IllegalScoreException: score out of range, score="+score;
    }

}
	//是addscore
	
	

08 字符串

编程题 1-8

## 1 StringBuffer
 StringBuffer buffer = new StringBuffer(str);
 System.out.println(buffer.reverse());
 
 
## 2 去除数字
 String newstr = str.replaceAll("\\d+", "");
 
## 3 

String[] split = line.split(";");
book.indexOf(":")
book.substring(0, index)
book.trim();
Integer.parseInt(bookPrice);

## 4 map
map.put();
map.get();
map.getOrDefault(name,0);
map.keySet();

 import java.util.*;
 public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String name=null;
        Map<String,Integer> map=new LinkedHashMap<String,Integer>();
		//是integer不是int
        
        while(true)
        {
            name=sc.next();
            if(name.equals("end"))
                break;
            map.put(name, map.getOrDefault(name, 0)+1);
			//map.getordefault
        }
        
        for(String name1:map.keySet())
        {
            System.out.println(name1+" "+map.get(name1));
        }
        
    }
 }
 
## 5合法字符
Character.isJavaIdentifierStart(s.charAt(0))
Character.isJavaIdentifierPart(s.charAt(i))
s.endsWith(".java")

09 其他

编程题 1-7

## 1 大数
num1 = new BigInteger(reader.next());
add,substract,multiply,divede,mod;

## 2进制
 public static String bin(int num1){//递归实现，将十进制转为二进制
        if(num1/2==0){//商为0时
            return num1%2 + "";//返回转换为String类型的余数
        }else{
            return bin(num1/2) + num1%2 + " ";//下一层递归的结果放左侧
        }
    }
## 3 随机数
 Random r = new Random(seed);
  double x =r.nextDouble()*2-1;
  
## 4 日历
import java.util.Calendar;
 import java.util.Scanner;
 public class Main{
 public static void main(String[] args) {
 Scanner sc=new Scanner(System.in);
        Calendar cal=Calendar.getInstance();
        int a=sc.nextInt();
        int count=0;
      if (a>=1998) {
    for (int i = 0; i <11; i++) {
       cal.set(Calendar.YEAR, a);
    cal.set(Calendar.MONTH, i);//月份少一
    cal.set(Calendar.DATE, 13);
    int t=cal.get(Calendar.DAY_OF_WEEK);
    if (t==6) {//天数+1
   count++;
    }
    }
       }
 System.out.println(count);
 }
 }