JOptionPane处理确定、取消和x按钮

Question

我的JOptionPane有一个问题，如果我不输入任何东西，无论我按什么(ok，cancel或x按钮(JOptionPane的右上角按钮))，它都会提示我，直到我输入一个正值。但是我只希望当我按下ok时出现提示。

如果我点击取消或x按钮(JOptionPane的右上角按钮)，它将关闭JOptionPane

我怎么能这样呢？

import javax.swing.JOptionPane;

public class OptionPane {
    public static void main(final String[] args) {
        int value = 0;
        boolean isPositive = false , isNumeric = true;
        do {
            try {
                value = Integer.parseInt(JOptionPane.showInputDialog(null,
                    "Enter value?", null));
            } catch (NumberFormatException e) {
                System.out.println("*** Please enter an integer ***");
                isNumeric = false;
            }

             if(isNumeric) {
                if(value <= 0) {
                    System.out.println("value cannot be 0 or negative");
                }

                else {
                    System.out.println("value is positive");
                    isPositive = true;
                }
            }
        }while(!isPositive);
    }
}

Answer 1

只需将代码移到＜code＞try

示例代码:

public static void main(final String[] args) {
    int value = 0;
    while (true) {
        try {
            value = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter value?", null));

            if (value <= 0) {
                System.out.println("value cannot be 0 or negative");
            } else {
                System.out.println("value is positive");
                break;
            }
        } catch (NumberFormatException e) {
            System.out.println("*** Please enter an integer ***");
        }
    }
}

Answer 2

JoptionPane#showInputDialog returns user's input, or null meaning the user canceled the input.

所以不是直接解析返回值。首先检查它是否为空(用户已取消)，如果不为空则什么也不做，然后解析整数值

Answer 3

基本方法如下所示：

在@MadProgrammer评论后更新。

import javax.swing.JFrame;
import javax.swing.JOptionPane;

public class DemoJOption {
    public static void main(String args[]) {
        int n = JOptionPane.showOptionDialog(new JFrame(), "Message", 
        "Title", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE, 
        null, new Object[] {"Yes", "No"}, JOptionPane.YES_OPTION);

        if (n == JOptionPane.YES_OPTION) {
            System.out.println("Yes");
        } else if (n == JOptionPane.NO_OPTION) {
            System.out.println("No");
        } else if (n == JOptionPane.CLOSED_OPTION) {
            System.out.println("Closed by hitting the cross");
        }
    }
}