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Question

捕获MouseEnter事件，再调用setSelected()函数！

Answer 1

MouseEnter事件是没有用的，这个我以前试过，需要用FocusListener，以下是代码：
package test.graph.frame;import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;public class TestFrame extends JFrame implements ActionListener{
    JPanel _Panel;
    JButton _Button;
    JTextField _Text;
    public TestFrame() {
        this.setTitle("你好，测试TestFrame");
        this.setSize(400,200);        /*构造结构*/
        _Panel = new JPanel(new BorderLayout());
        _Button = new JButton("发送信息");
        _Button.addActionListener(this);
        _Text = new JTextField("中国人都是好样的");
        _Text.addFocusListener(new TextFocusListener());
        _Panel.add(_Text,BorderLayout.CENTER);
        _Panel.add(_Button,BorderLayout.SOUTH);
        this.getContentPane().add(_Panel);
    }    public void actionPerformed(ActionEvent event){
        if (event.getSource() == this._Button){
            String message = this._Text.getText();
            if (message != null)
                System.out.println(message);
                
        }
    }    class TextFocusListener implements FocusListener{
        public void focusLost(FocusEvent event){
            System.out.println("focusLost!");
        }
        public void focusGained(FocusEvent event){
            System.out.println("focusGained!");
            JTextField textField =  (JTextField)event.getSource();
            textField.selectAll();
        }
    }
}

Answer 2

楼上正确。
MouseListener t new yourClass() 
其中yourClass实现了MouseListener
tf.addMouseListener(t);//tf为textField

Answer 3

MouseEntered事件无用？不会吧，如下代码怎么解释
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class bean3 extends JFrame {
  JPanel contentPanel=(JPanel) this.getContentPane();
  JTextField jt=new JTextField("123456",20);
  JTextField jt1=new JTextField("abcdef",20);  public bean3() throws Exception {
    super("myFrame");
    this.setSize(800,600);
    this.setResizable(false);
    this.setLocation(this.getToolkit().getScreenSize().width/2-400,this.getToolkit().getScreenSize().height/2-300);
    contentPanel.setLayout(new FlowLayout());
    contentPanel.add("Center",jt);
    contentPanel.add("Center",jt1);
    jt.addMouseListener(new MouseAdapter() {
      public void mouseEntered(MouseEvent e) {
        ((JTextField)e.getSource()).requestFocus();
        ((JTextField)e.getSource()).selectAll();
      }
    });
    this.setVisible(true);
  }  public static void main(String[] args) throws Exception {
    new bean3();
  }  protected void processWindowEvent(WindowEvent e) {
    super.processWindowEvent(e);
    if (e.getID() == WindowEvent.WINDOW_CLOSING) {
      System.exit(0);
    }
  }
}