如何在鼠標單擊JTextField時清除JTextField

Question

當鼠標在該文本字段中單擊時，我需要使該程序清除文本字段中的文本。 我嘗試了一些東西，但沒有一個還沒有為我工作。

以下是完整的代碼：

public class TimerClassPanel extends JFrame implements MouseListener{

    public TimerClassPanel(){
        setTitle("Timer Class");
        setSize(WIDTH, HEIGHT);

        timer = new Timer(DELAY, new TimerEventHandler());

        pane = getContentPane();
        pane.setLayout(null);

        int r = (int)(9.0 * Math.random()) + 1;
        String str2 = Integer.toString(r);

        label = new JLabel(str2, SwingConstants.CENTER);
        label.setSize(150,30);
        label.setLocation(0,0);

        textField = new JTextField();
        textField.setSize(150,30);
        textField.setLocation(150,0);

        startB = new JButton("Start");
        startbh = new StartButtonHandler();
        startB.addActionListener(startbh);
        startB.setSize(100,30);
        startB.setLocation(0,30);

        stopB = new JButton("Stop");
        stopbh = new StopButtonHandler();
        stopB.addActionListener(stopbh);
        stopB.setSize(100,30);
        stopB.setLocation(100,30);

        exitB = new JButton("Exit");
        ebHandler = new ExitButtonHandler();
        exitB.addActionListener(ebHandler);
        exitB.setSize(100,30);
        exitB.setLocation(200,30);      

        pane.add(label);

        pane.add(textField);
        pane.add(startB);
        pane.add(stopB);
        pane.add(exitB);

        timer = new Timer(DELAY, new TimerEventHandler());

        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    private class TimerEventHandler implements ActionListener{
        public void actionPerformed(ActionEvent e){
            int r = (int)(9.0 * Math.random()) + 1;
            String str = Integer.toString(r);
            currentNum = "";
            currentNum = str;
            label.setText(str);
            repaint();
        }
    }

    public class StartButtonHandler implements ActionListener{
        public void actionPerformed(ActionEvent e){
            timer.start();
        }
    }

    public class StopButtonHandler implements ActionListener{
        public void actionPerformed(ActionEvent e){
            timer.stop();
        }
    }

    private class ExitButtonHandler implements ActionListener{
        public void actionPerformed(ActionEvent e){
            System.exit(0);
        }
    }

    public static void main(String[] args){
        TimerClassPanel timerPanel = new TimerClassPanel();
        JOptionPane.showMessageDialog(null, "Type your guess (int between 1-9)" +
                " in the field then press 'ENTER'");
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        if( e.getX() > 150 && e.getX() < 300 && e.getY() > 0 && e.getY() < 30)
        {   
            textField.setText("");
            repaint();
        }
    }

    @Override
    public void mouseEntered(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseExited(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mousePressed(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseReleased(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }
}

Answer 1

TL; DR

無論如何，注冊MouseAdapter並覆蓋mouseClicked對我MouseAdapter ，

import java.awt.FlowLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class ClickAndClearDemo {
    private static void createAndShowGUI(){
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout(FlowLayout.CENTER, 20, 20));

        final JTextField textField = new JTextField("Enter text here...");
        textField.addMouseListener(new MouseAdapter(){
            @Override
            public void mouseClicked(MouseEvent e){
                textField.setText("");
            }
        });

        frame.add(textField);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){
            @Override
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

我希望這個例子讓你開始朝着正確的方向前進！

Answer 2

您只需將FocusListener添加到文本字段即可。

 final JTextField textField = new JTextField("Enter text here...");
    textField.addFocusListener(new FocusListener(){
        @Override
        public void focusGained(FocusEvent e){
            textField.setText("");
        }
    });

Answer 3

這對我有用。 當然，單擊時會清除文本，您可以輸入新文本。 要通過單擊再次清除文本，文本字段必須失去焦點，然后從鼠標重新獲得焦點。 我不完全確定你在這里尋找什么。

import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.JFrame;
import javax.swing.JTextField;

public class ClickTextField extends JTextField implements MouseListener{

public static void main(String[] args) {
    new ClickTextField();
}

public ClickTextField() {
    addMouseListener(this);

    JFrame J = new JFrame();
    J.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    J.setSize(100,100);
    J.getContentPane().add(this);
    setText("Texty text...");
    J.show();
}

@Override
public void mouseClicked(MouseEvent e) {

    setText("");

}

@Override
public void mousePressed(MouseEvent e) {
    // TODO Auto-generated method stub

}

@Override
public void mouseReleased(MouseEvent e) {
    // TODO Auto-generated method stub

}

@Override
public void mouseEntered(MouseEvent e) {
    // TODO Auto-generated method stub

}

@Override
public void mouseExited(MouseEvent e) {
    // TODO Auto-generated method stub

}

}

Answer 4

是要清除'提示'文字嗎？

我想這就是你要做的......

textField.addMouseListener(new MouseAdapter())
    {
        public void mouseClicked(MouseEvent e)
        {
            if(textField.getText().equals("Default Text"))
            {
                textField.setText("");
                repaint();
                revalidate();
            }           
        }
    });

Answer 5

我也必須這樣做。 我所做的只是制作一個自定義的JTextField 。 就像是：

import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.JTextField;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

@SuppressWarnings("serial")
public class InputField extends JTextField implements MouseListener,ActionListener
{
public InputField(String text) 
{
    super(text);
    super.setHorizontalAlignment(RIGHT);
    super.addMouseListener(this);
}

@Override
public void mouseClicked(MouseEvent e) 
{
    // TODO Auto-generated method stub
    if (getText().equals("0.0"))
    {
        setText("");
    }
}

@Override
public void mouseEntered(MouseEvent e) 
{

}

@Override
public void mouseExited(MouseEvent e)
{

}

@Override
public void mousePressed(MouseEvent e) {
    maybeShowPopup(e);
    // if the mouse is pressed and "0.0" is the text, we erase the text
    if (getText().equals("0.0"))
    {
        setText("");
    }
}

@Override
public void mouseReleased(MouseEvent e) 
{
    maybeShowPopup(e);
}

private void maybeShowPopup(MouseEvent event)
{
    //if the user clicked the right mouse button
    if (javax.swing.SwingUtilities.isRightMouseButton(event))
    {
        //create (and show) the popup
        createPopup().show(event.getComponent(), event.getX(), event.getY());
    }
}

private JPopupMenu createPopup()
{
    JPopupMenu popupMenu = new JPopupMenu();
    //add the clearTextOption to the JPopupMenu
    JMenuItem clearTextOption = new JMenuItem("Clear text");
    clearTextOption.addActionListener(this);
    popupMenu.add(clearTextOption);
    return popupMenu;
}

@Override
public void actionPerformed(ActionEvent arg0) {
    //clear the TextField
    setText("");
}

} //end custom TextField

在這個自定義TextField中，我只使用了一個MouseListener 。 制作自定義產品的優點是：

1. 我可以直接實現MouseListener（而不必使用一些令人困惑的匿名內部類）
2. 我可以做一些自定義（包括用戶選擇右鍵單擊TextField並從PopupMenu中選擇一個項目。）我目前正在為用戶復制，粘貼和拖放選項。
3. 我可以做到這一切，而不會在主要的.java文件中加入額外的代碼，這些代碼可以在以后挖掘更多內容。 雖然MikeWarren.getAnswer(this) extends richard.getAnswer(this) ，但我想我會詳細說明一下，並在我的一個程序中顯示一些我實際使用過的代碼。

Answer 6

public JTextField userInput;

在執行文本后立即：

userInput.setText（ “”）; //空

這應該做。

Answer 7

 jTextField2.addMouseListener(new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent e) {
                if (e.getButton()==1) {
                    jTextField2.setText("");
                }//3 = for right click 
                //2 for middlemouse
            }

            @Override
            public void mousePressed(MouseEvent e) {

            }

            @Override
            public void mouseReleased(MouseEvent e) {

            }

            @Override
            public void mouseEntered(MouseEvent e) {

            }

            @Override
            public void mouseExited(MouseEvent e) {

            }
        });

你也可以嘗試這種方法。