靠近 JFrame 窗口

问题描述

我有一个 JFrame，我想按“X”键（关闭 JFrame）来确认我是否真的要关闭应用程序。如果我点击“否”，它会关闭应用程序。

为什么我选择“否”不起作用？

    setDefaultCloSEOperation(javax.swing.WindowConstants.DO_nothing_ON_CLOSE);
    addWindowListener(new java.awt.event.WindowAdapter() {
        @Override
        public void windowClosing(java.awt.event.WindowEvent evt){
            if (JOptionPane.showConfirmDialog(rootPane,"Confirm out?","AppLocal",JOptionPane.ERROR_MESSAGE) == JOptionPane.ERROR_MESSAGE){
                dispose();
            }
        }
    });

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解决方法

方法：
int javax.swing.JOptionPane.showConfirmDialog(Component parentComponent,Object message,String title,int optionType) throws HeadlessException

在optionType参数中，你必须使用：

• JOptionPane.YES_NO_OPTION
• JOptionPane.YES_NO_CANCEL_OPTION
• JOptionPane.OK_CANCEL_OPTION

可用的返回值是：

    //
    // Return values.
    //
    /** Return value from class method if YES is chosen. */
    public static final int         YES_OPTION = 0;
    /** Return value from class method if NO is chosen. */
    public static final int         NO_OPTION = 1;
    /** Return value from class method if CANCEL is chosen. */
    public static final int         CANCEL_OPTION = 2;
    /** Return value form class method if OK is chosen. */
    public static final int         OK_OPTION = 0;
    /** Return value from class method if user closes window without selecting
     * anything,more than likely this should be treated as either a
     * <code>CANCEL_OPTION</code> or <code>NO_OPTION</code>. */
    public static final int         CLOSED_OPTION = -1;

因此，您的代码可以是：

setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
addWindowListener(new java.awt.event.WindowAdapter() {
    @Override
    public void windowClosing(java.awt.event.WindowEvent evt) {
        if (JOptionPane.showConfirmDialog(rootPane,"Confirm out?","AppLocal",JOptionPane.YES_NO_OPTION) == JOptionPane.YES_OPTION
        ) {
            dispose();
        }
    }
});