java - JButton 以编程方式显示工具提示 : actionMap. get ("postTip") 为空

Question

我需要在 button2 获得焦点时以编程方式显示工具提示。 (我按 Tab 键是因为 initially focus at button1)

            JButton button = new JButton("Button 1");

            JButton button2 = new JButton("Button 2");
            button2.setToolTipText("tooltip2");
            button2.addFocusListener(new FocusListener());

我指的是 code通过@camickr

private class FocusListener extends FocusAdapter {
 public void focusGained(FocusEvent e)
 {
    JComponent component = (JComponent)e.getSource();
    Action toolTipAction = component.getActionMap().get("postTip");

但 toolTipAction 设置为空。

我已经使用这段代码打印了 ActionMap 的所有条目

        ActionMap actionMap = component.getActionMap();
        Object[] actionMapKeys = actionMap.allKeys();

        for (int i = 0; i < actionMapKeys.length; i++) {
            Object key = actionMapKeys[i];
            System.out.println(key.toString() + " : " + actionMap.get(key).toString());
        }

这就是它带给我的

pressed : javax.swing.plaf.basic.BasicButtonListener$Actions@49cf9f
released : javax.swing.plaf.basic.BasicButtonListener$Actions@1de0b5e

那么，如果我的 toolTipAction 为 null，我该如何调用这段代码呢？

ActionEvent postTip = new ActionEvent(component, ActionEvent.ACTION_PERFORMED, "");
toolTipAction.actionPerformed(postTip);

Answer 1

actuall I want to show tooltip on some network event, which has nothing to do with mouse. but I have started experiments with focus gained by Tab key

• 使用JWindow(未修饰的JDialog)或JLabel代替ToolTip，的例子>JLabel by @Guillaume Polet和 here

• 您可以将此容器放在鼠标光标位置或坚持绝对坐标，指向可见的GUI

• 标准可能(可能很烦人)参见 SystemTray and TrayIcon#displayMessage