Java JButton.setAction(...) null 的按钮文本

Question

以下代码呈现 JButton 没有文本：

public abstract class Test {

    public static void main(String... args) {

        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException e) {
            e.printStackTrace();
        }

        SwingUtilities.invokeLater(() -> {
            JFrame frame = new JFrame();
            JPanel panel = new JPanel();

            String text = "Invisible";
            JButton button = new JButton(text); // blank button rendered ???

            System.out.println(button.getText()); // prints Invisible

            button.setAction(new AbstractAction() {     
                @Override
                public void actionPerformed(ActionEvent arg0) {
                    // do nothing
                }
            });

            System.out.println(button.getText()); // prints null ???

            button.setFocusable(false);

            button.setPreferredSize(new Dimension(100, 40));

            panel.add(button);

            frame.setResizable(false);
            frame.getContentPane().add(panel);

            frame.pack();
            frame.setVisible(true);

        });

    }

}

如果我删除对 button.setAction(...) 的调用，它会呈现包含文本的按钮。

或者：

public abstract class Test {

    public static void main(String... args) {

        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException e) {
            e.printStackTrace();
        }

        SwingUtilities.invokeLater(() -> {
            JFrame frame = new JFrame();
            JPanel panel = new JPanel();

            String text = "Invisible";
            JButton button = null;
            button = new JButton(new AbstractAction() {     
                @Override
                public void actionPerformed(ActionEvent arg0) {
                    // do nothing
                }
            });

            button.setText(text); // renders the button with text
            System.out.println(button.getText()); // prints Invisible obviously

            button.setFocusable(false);

            button.setPreferredSize(new Dimension(100, 40));

            panel.add(button);

            frame.setResizable(false);
            frame.getContentPane().add(panel);

            frame.pack();
            frame.setVisible(true);

        });

    }

}

工作正常，但有一些令人讨厌的含义，例如 无法更改按钮操作 之后不重置其文本。

为什么？！

Answer 1

最好在 JButton 构造函数中输入文本，因为 JButton 构造函数的参数是字符串而不是字符串变量。

JButton button = new JButton("Invisible");

Answer 2

@Dima Maligin

未回复，将被删除
应声明 Swing Action（也覆盖 isEnabled，这很重要）

.

 private class SwingAction extends AbstractAction {

   //or public Action SwingAction() {
   //       return new AbstractAction("Invisible") {
   //           here to override AbstractAction   
   //       } 
   //    } 

    public SwingAction() {
        putValue(NAME, "Invisible"); // bounds properties
        putValue(SHORT_DESCRIPTION, "Invisible");
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // do nothing
    }
}

Java JButton.setAction(...) null 的按钮文本

Java JButton.setAction(...) null's button text

java

swing

action

jbutton