Java do ... while the while loop

1.do ... difference while the while loop statement

while loop

First determine, after executing the statement. Before the statement is executed, it must first control loop.

public class Demo {
	public static void main(String[] args) {
		int i=0,j=0;
		System.out.println("befor while j="+j);
		while(i>0) {
			j++;
		}
		System.out.println("after while j="+j);
	}
}

The results as shown below:

do ... while loop

To execute the statement after the judgment. Before executing the statement, no need to consider the control loop.

public class Demo {
	public static void main(String[] args) {
		int i=0,j=0;
		System.out.println("befor while j="+j);
		do {
			j++;
		}while(i>1);
		System.out.println("after while j="+j);
	}
}

The results as shown below:

2.do ... while the password twice to achieve parity

import java.util.Scanner;

public class Demo {
	public static void main(String[] args) {
		Scanner input=new Scanner(System.in);
		String pwd1;
		String pwd2;
		
		do {
			System.out.println("请输入密码：");
			pwd1=input.nextLine();
			System.out.println("请再次输入密码：");
			pwd2=input.nextLine();
			if(!pwd1.equals(pwd2)) {
				System.out.println("您输入的密码不一致，请重新输入!");
			}
			System.out.println();
		}while(!pwd1.equals(pwd2));
		System.out.println("密码设置成功!");
	}		
}

The results as shown below: