JavaSE String练习 java 代码答案

输入一个字符串，显示长度，第一个和最后一个字符

import java.util.Scanner;

public class java01 {

    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);//输入一个字符串，显示长度，第一个和最后一个字符
        String abs;
        abs=in.nextLine();
        System.out.println(abs.length());
        char absd[]=abs.toCharArray();
        System.out.println(absd[0]);
        System.out.println(absd[abs.length()-1]);
    }
}

输入两个字符串，检测第二个是否是第一个的子串

import java.util.Scanner;

public class java01 {

    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        String a1,a2;
        a1=in.nextLine();
        a2=in.nextLine();
//            if (a1.equals(a2))
//            System.out.println("字符串2是1的子串");
        //System.out.println(a1.length());
//        for (int i=0;i
//            String a3;
//            a3=a1.substring(i);
//            if (a3.equals(a2))
//            System.out.println("字符串2是1的子串");
//        }
        System.out.println(a2+(a1.indexOf(a2)>0?"是":"不是")+"a1的子串");
    }
}

public class Clone implements Cloneable{
	   private double length;
	   public Clone(double length){
		   this.length = length;
	   }
	   public void setLength(double length){
		   this.length = length;
	   }
	   public double getLength(){
		   return length;
	   }
	   public boolean equals(Clone s){
		 if(this.length==s.length){
			return true;
		 }else{
			return false;
		 }
	   }
	   public String toString(){
		  return "Square[length="+length+"]";
	   }
	   public static void main(String args[]) 
          throws CloneNotSupportedException{
		Clone sq1 = new Clone(0);
		sq1.setLength(10);
		System.out.println(sq1);
		Clone sq2 = (Clone)sq1.clone();
		System.out.println(sq1);
		System.out.println(sq1.equals(sq2));
	  }
}

public class java01 {

    public static void main(String[] args) {
//        Random random1=new Random(6);
        int array[]=new int[1000];
        int arrayMath[]=new int[6];
        for (int i=0;i<1000;i++){
            array[i]=(int) (Math.random()*6+1);
        }
        arrayMath= arrayList(array);
        for (int k:arrayMath){
            System.out.print(k+" ");
        }
    }

    static int[] arrayList(int[] array) {
        int arrayMath[]=new int[6];
        for (int i=0;i<1000;i++){
            for (int j=1,k=0;j<7;j++,k++)
            if (array[i]==j)
                arrayMath[k]++;
        }
        return arrayMath;
    }
}

public class java01 {

    public static void main(String[] args) {
        double area = 0;        // 存放面积变量
        double degree = 30 ;    // 存放角度变量
        area = 1 / 2.0 * 4.0 * 5.0 * Math.sin(Math.toRadians(degree));
        System.out.println("该三角形的面积为：" + area);
    }
}