第五个Java程序

import java.util.Scanner;

public class demol1 {
    public static void main(String[] args) {
        Scanner s=new Scanner(System.in);
        System.out.print("请输入要检查的字符串：");
        StringBuffer str=new StringBuffer();
        //定义一个变量接受输入的字符串
        String OldString=s.next();
        //判断反转后的字符串与原字符串是否相等
        if(str.append(OldString).reverse().toString().equals(OldString)){
            System.out.println("是");
        }else System.out.println("不是");


    }
}

public class demol2 {
    public static void main(String[] args) {
        int []arr={1,2,3};
        System.out.println(add(arr));

    }
    //定义一个方法
    public static String add(int []arr) {
        StringBuffer sb=new StringBuffer();
        sb.append("[");
        for (int i = 0; i < arr.length; i++) {
            sb.append(arr[i]);
            if(i==arr.length-1)break;
            sb.append(",");
        }
        return sb.toString()+"]";
    }
}

import java.util.StringJoiner;

public class demol2 {
    public static void main(String[] args) {
        int []arr={1,2,3};
        System.out.println(add(arr));
    }
    //定义一个方法
    public static String add(int []arr) {
        StringJoiner sj=new StringJoiner(",","[","]");
        for (int i = 0; i < arr.length; i++) {
            sj.add(arr[i]+"");
        }
        return  sj.toString();
    }
}