int[] arr = {1,2,3};

"{1,2,3}";

public class test1 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] arr = {1,2,3};
		System.out.println(Array2String(arr));
	}
	public static String Array2String(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)
				sb.append(",");
		}
		sb.append("}");
		return sb.toString();
		
	}

}

字符串反转

“abc”

“cba”

import java.util.Scanner;

public class test2 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s =new String();
		s=sc.nextLine();
		StringBuffer sb = new StringBuffer(s);
		StringBuffer sb1=sb.reverse();
		System.out.println(sb1);
	}
}