java - 为什么while循环一直循环

Question

当我声明 flag false 时，为什么 while 循环继续循环？一旦我输入正确的输入，程序就应该结束。任何帮助将不胜感激。刚接触java。非常感谢大家!

import javax.swing.JOptionPane;
import java.util.*;


public class Project1Chang
{
public static void main(String[] args)
{
    String name;
    String sex;
    int height;
    boolean flag = true;

    JOptionPane.showMessageDialog (null, "This program calculates tidal volume.", "Tidal Volume Calculator", JOptionPane.INFORMATION_MESSAGE);

    name = JOptionPane.showInputDialog("What is your name?");
    sex = JOptionPane.showInputDialog("What is your sex?");

    while (flag = true)
    {
        height = Integer.parseInt (JOptionPane.showInputDialog("What is your height? (48-84 inches or 114-213 centimeters) \nEnter whole numbers only."));

        if (height <= 84 && height >= 48)
        {
            if (sex.equalsIgnoreCase("male") || sex.equalsIgnoreCase("m"))
            {
                double malePbwInch = 50 + 2.3 * (height - 60);
                JOptionPane.showMessageDialog(null, malePbwInch);
                flag = false;
            }
        }
        else if (height <= 213 && height >= 114)
        {
            if (sex.equalsIgnoreCase("male") || sex.equalsIgnoreCase("m"))
            {
                double malePbwCm = 50 + .91 * (height - 152.4);
                JOptionPane.showMessageDialog(null, malePbwCm);
                flag = false;
            }
        }
        else
        {
            JOptionPane.showMessageDialog(null, "This is an invalid input. Try again.");
        }
    }
}

}

Answer 1

即使是经验丰富的程序员也会时不时地犯这样的错误:您将 true 分配给 flag，因此条件始终为 true。您需要双等于比较运算符

while (flag == true)

或者只是

while (flag)