java - 按键事件未被调用

Question

public GuiC() {
    getContentPane().addKeyListener(new KeyAdapter() {
        @Override
        public void keyPressed(KeyEvent e) {
            System.out.println("hi");

        }
    });
    setBackground(Color.GREEN);
    setTitle("Hi!");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 500, 500);
    getContentPane().setLayout(null);

}

所以这是我的框架，我在这里做错了什么吗？因为当我按任意键时不会调用键事件，请帮忙:)

Answer 1

您可能需要请求焦点。

public GuiC() {
    this.getContentPane().requestFocus(); //request focus here
    this.getContentPane().addKeyListener(new KeyListener() {
    @Override
    public void keyPressed(KeyEvent e) {
        System.out.println("hi: " + e.getKeyChar());

    }
});
    setBackground(Color.GREEN);
    setTitle("Hi!");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 500, 500);
    getContentPane().setLayout(null);

}

补充阅读:How to Write a Key Listener