60 数组内交换头尾；61打乱顺序

package com.fqs.test;

import java.util.Arrays;
public class hello {
    public static void main(String[] args) {
      //交换数组头尾交换
        //交换前 12345
        //交换后 54321
        int []arr={1,2,3,4,5};
        int temp=arr[0];
        for (int i = 0,j=arr.length-1; i <=j/2 ; i++,j--) {
            temp=arr[i];
            arr[i]=arr[j];
            arr[j]=temp;
            
        }
        System.out.println("交换后的数组："+Arrays.toString(arr));



    }
}

 打乱顺序

package com.fqs.test;

import java.util.Arrays;
import java.util.Random;

public class hello {
    public static void main(String[] args) {
      //打乱数组中的顺序
        int []arr={1,2,3,4,5};
        Random r=new Random();
        int temp=arr[0];
        for (int i = 0; i <arr.length ; i++) {
            //随机下标和i下标交换
            int r_num=r.nextInt(5);
            System.out.println("随机数r_num:"+r_num);
            temp=arr[i];
            arr[i]=arr[r_num];
            arr[r_num]=temp;
        }
        System.out.println(Arrays.toString(arr));
    }
}