Java JOptionPane showConfirmDialog如果else语句不起作用

无论我做什么，没有部分永远不会起作用，我已经尝试了另一个if，else if，else，方括号，无括号。无论我点击什么，它都会打印hello。如果我按no，我希望系统退出

import javax.swing.*;

class ok
{
    public static void main(String[] args)
    { 
        int dialogButton = JOptionPane.YES_NO_OPTION;
        JOptionPane.showConfirmDialog (null,"Can you come at my house on 18th??" ," SERIOUS QUESTION",dialogButton,3);
        if (dialogButton == JOptionPane.YES_OPTION) {
            JOptionPane.showMessageDialog(null, "HELLO");
        } else if (dialogButton == JOptionPane.NO_OPTION)
            System.exit(0);
    }
}

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您没有捕获JOptionPane.showConfirmDialog的返回值。大概是这样的：

class ok
{
    public static void main(String[] args)
    { 
        int options = JOptionPane.YES_NO_OPTION;
        int result = JOptionPane.showConfirmDialog(null, "Can you come at my house on 18th?" ,"SERIOUS QUESTION", options, 3);
        if (result == JOptionPane.YES_OPTION) {
            JOptionPane.showMessageDialog(null, "HELLO");
        } else if (result == JOptionPane.NO_OPTION) {
            System.exit(0);
        } 
    }
}

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您没有捕获JOptionPane.ShowConfirmDialog的返回值我该怎么做？我是编程新手