Java：TextField Listener不起作用

Question

我的代码如下：

package playingwithjava;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
 *
 * @author user
 */
public class Window extends JFrame implements ActionListener{
    //init stuff
    Container ca=getContentPane();
    GridBagLayout gridLayout= new GridBagLayout();
    GridBagConstraints lol=new GridBagConstraints();

    //actual important stuff

    JButton done=new JButton("Done!");
    JTextField text=new JTextField("",25);
    JLabel label=new JLabel("Your name is:");

    public Window(int x,int y)
    {
        super("Playing With Java");
        setSize(x,y);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        ca.setLayout(gridLayout);
        //start of the code
        lol.gridx=0;lol.gridy=0;
        ca.add(label,lol);

        lol.gridx=0;lol.gridy=1;
        text.addActionListener(this);
        ca.add(text,lol);

        lol.gridx=1;lol.gridy=1;
        //done.setEnabled(false);
        done.addActionListener(this);
        ca.add(done,lol);

        //ending
        setContentPane(ca);
        setVisible(true);
    }
    @Override
    public void actionPerformed(ActionEvent event)
    {
        if(event.getSource()==done)
        {
            JOptionPane.showMessageDialog(null,"Hello, "+text.getText()+"!","Hi!",JOptionPane.NO_OPTION);
        }
        if(event.getSource()==text)
        {
            JOptionPane.showMessageDialog(null,"a","Hi!",JOptionPane.NO_OPTION);

        }
    }
}

当我更改TextField中的文本时，我不明白为什么没有任何反应。

Answer 1

按Enter键时调用ActionListener。

要监听文本字段中的更改，您应该使用DocumentListener。有关详细信息，请参阅How to Write a Document Listener。