java - 需要我的 GUI 从 JTextField 读取并在 JPanel 中显示

Question

我已向文本字段添加了一个 Action 监听器。当按下 btnReadString(按钮读取字符串)时，程序应该读取文本字段上的内容并显示在 JPanel 上。但面板上没有任何显示。

stringTextField.addActionListener(new ActionListener() {
    public void stringTextField (java.awt.event.ActionEvent e) {
        if(e.getSource()==btnReadString) //when the button is pressed
        {
            String stringParameter = stringTextField.getText(); //gets the text and puts it on this string called "stringParameter"
            textPane.setText(stringParameter);//the JPanel is set to what is on the string. 
            }

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub

    }
});

Answer 1

ActionListener 的功能应该放在 actionPerformed 方法中，因为没有调用 stringTextField 方法...

stringTextField.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        if(e.getSource()==btnReadString) //when the button is pressed
        {
            String stringParameter = stringTextField.getText(); //gets the text and puts it on this string called "stringParameter"
            textPane.setText(stringParameter);//the JPanel is set to what is on the string. 
        }
    }
});

但是，根据代码，ActionListener 应该附加到 btnReadString 而不是字段，因为上述逻辑永远不会导致执行任何内容(如事件源永远不会是 btnReadString)

btnReadString.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        String stringParameter = stringTextField.getText(); //gets the text and puts it on this string called "stringParameter"
        textPane.setText(stringParameter);//the JPanel is set to what is on the string. 
    }
});

我建议仔细看看 How to Write an Action Listener和 How to Use Buttons, Check Boxes, and Radio Buttons了解更多详情