What does while mean in java

The while loop in Java is used to repeatedly execute code until a certain condition is false. Working principle: 1. If the condition is true, execute the loop body; 2. Check the condition again, and if it is true, execute the loop body until the condition is false. Usage scenarios: Repeated execution of code when conditions are unknown or can change dynamically, such as prompting for valid values, file iteration, and repeating tasks to specific targets.

Meaning of while in Java

While loop is a control flow used to repeatedly execute a set of statements A structure that continues to execute as long as a certain condition is true.

Syntax

<code class="java">while (condition) {
  // 要执行的代码
}</code>

How it works

The while loop initially checks whether the condition is true. If true, execute the code within the loop body. Then, check the conditions again. If it's still true, the loop body is executed again. This process continues until the condition becomes false.

When to use while loops

While loops are most often used when execution conditions are unknown or can change dynamically when code needs to be executed repeatedly. For example:

• Prompt the user for input before entering a valid value
• Iterate over all lines in the file
• Repeat a task until a specific goal is reached

Example

The following is an example of a while loop that will prompt the user to enter a number and continue until the user enters a non-negative number:

<code class="java">import java.util.Scanner;

public class WhileExample {

  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    int number;

    while ((number = input.nextInt()) < 0) {
      System.out.println("请输入一个非负数：");
    }

    System.out.println("感谢您的输入：" + number);
  }
}</code>

The above is the detailed content of What does while mean in java. For more information, please follow other related articles on the PHP Chinese website!