java.awt.Robot keyPress事件持续按下

Question

I am trying to create my own virtual keyboard in Java. I am using Robot's keyPress() event to trigger the KeyEvent to a text field. Key event is working but it keep on printing the key that I pressed. Here is my code please check what I am doing wrong?

Code for creating keyboard

package virtualkeyboard;

import java.awt.AWTException;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Robot;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JTextField;

public class Keyboard extends JDialog {

    private static final long serialVersionUID = 1L;

    private JTextField txtField;

    public Keyboard(JTextField txt) {

        this.txtField = txt;
        setModalityType(ModalityType.APPLICATION_MODAL);
        setLayout(new GridLayout(3, 3));

        for (int i = 0; i <= 9; i++){
            createButton(Integer.toString(i));
        }

        pack();
    }

    private void createButton(String label) {
        JButton btn = new JButton(label);
        btn.setFocusPainted(false);
        btn.setPreferredSize(new Dimension(100, 100));
        Font font = btn.getFont();
        float size = font.getSize() + 15.0f;
        btn.setFont(font.deriveFont(size));

        btn.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseReleased(MouseEvent e) {

                txtField.requestFocus();

                Robot robot;

                try {

                    robot = new Robot();

                    if(label.equals("0"))
                        robot.keyPress(KeyEvent.VK_0);
                    else if(label.equals("1"))
                        robot.keyPress(KeyEvent.VK_1);
                    else if(label.equals("2"))
                        robot.keyPress(KeyEvent.VK_2);
                    else if(label.equals("3"))
                        robot.keyPress(KeyEvent.VK_3);
                    else if(label.equals("4"))
                        robot.keyPress(KeyEvent.VK_4);
                    else if(label.equals("5"))
                        robot.keyPress(KeyEvent.VK_5);
                    else if(label.equals("6"))
                        robot.keyPress(KeyEvent.VK_6);
                    else if(label.equals("7"))
                        robot.keyPress(KeyEvent.VK_7);
                    else if(label.equals("8"))
                        robot.keyPress(KeyEvent.VK_8);
                    else if(label.equals("9"))
                        robot.keyPress(KeyEvent.VK_9);

                } catch (AWTException e1) {
                    e1.printStackTrace();
                }
            }
        });

        add(btn);
    }
}

Window with a textfield

package virtualkeyboard;

import java.awt.Dimension;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JDialog;
import javax.swing.JTextField;

public class WindowOne extends JDialog {

    private JTextField txtField = new JTextField();

    private Keyboard keyboard = new Keyboard(txtField);

    public WindowOne(){

        setSize(new Dimension(250,30));

        txtField.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                if(isEnabled()){
                    Point p = getLocationOnScreen();
                    p.y += 30;
                    keyboard.setLocation(p);
                    keyboard.setVisible(true);
                }
            }
        });

        add(txtField);

    }

    public static void main(String[] args) {
        new WindowOne().setVisible(true);
    }

}

Edits:

I made the following changes in code and made the JTextfield focusable while press the button.

private void createButton(String label,JTextField txt) {

        JButton btn = new JButton(label);
        btn.setFocusPainted(false);
        btn.setPreferredSize(new Dimension(100, 100));
        Font font = btn.getFont();
        float size = font.getSize() + 15.0f;
        btn.setFont(font.deriveFont(size));
        btn.setFocusable(false);

        btn.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseClicked(MouseEvent e) {

                txt.getParent().requestFocus();
                txt.requestFocus();

                robot.delay(100);

                if(label.equals("0"))
                    robot.keyPress(KeyEvent.VK_0);
                else if(label.equals("1"))
                    robot.keyPress(KeyEvent.VK_1);
                else if(label.equals("2"))
                    robot.keyPress(KeyEvent.VK_2);
                else if(label.equals("3"))
                    robot.keyPress(KeyEvent.VK_3);
                else if(label.equals("4"))
                    robot.keyPress(KeyEvent.VK_4);
                else if(label.equals("5"))
                    robot.keyPress(KeyEvent.VK_5);
                else if(label.equals("6"))
                    robot.keyPress(KeyEvent.VK_6);
                else if(label.equals("7"))
                    robot.keyPress(KeyEvent.VK_7);
                else if(label.equals("8"))
                    robot.keyPress(KeyEvent.VK_8);
                else if(label.equals("9"))
                    robot.keyPress(KeyEvent.VK_9);

                requestFocusInWindow();
            }
        });
        add(btn);
    }

If I press a button it's keep on printing the number in textfield. But event is fired only once.

Please check.

Answer 1

I got the solution for my problem,

For every keyPress event we need to trigger the appropriate keyRelease event then only it will stop the keyPress event, otherwise it will considred as a long press.

Changed this line

if(keyCode.equals("VK_0")){
    robot.keyPress(KeyEvent.VK_0);
}

to

if(keyCode.equals("VK_0")){
    robot.keyPress(KeyEvent.VK_0);
    robot.keyRelease(KeyEvent.VK_0);
}