How do I create an on screen keyboard in java?

Question

I'm working on a school project where we have to create a virtual smartphone, to run on a computer.

My problem is that I need to create a keyboard on the screen (like on an smartphone), which you can then use by clicking with your mouse. I could just create every single JButton, but that will take a really long time. So I was hopping that someone knew some sort of algorithm that creates all the buttons and places them correctly on the screen.

Thank you in advance :)

Answer 1

You could construct the buttons through the use of for loops. One loop for every keyboard row is a plausible approach.

String row1 = "1234567890";
String row2 = "qwertyuiop";
// and so forth
String[] rows = { row1, row2, .. };
for (int i = 0; i < rows.length; i++) {
    char[] keys = rows[i].toCharArray();
    for (int j = 0; i < keys.length; j++) {
        JButton button = new JButton(Character.toString(keys[j]));
        // add button
    }
}
// add special buttons like space bar

This could be done more elegantly through a more OOP approach, but this basic loop system will work.

Answer 2

This simple example might help you:

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;


@SuppressWarnings("serial")
public class MainFrame extends JFrame
{
    private JTextField txt;
    private PopUpKeyboard keyboard;

    public MainFrame()
    {
        super("pop-up keyboard");
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        txt = new JTextField(20);
        keyboard = new PopUpKeyboard(txt);

        txt.addMouseListener(new MouseAdapter()
        {
            @Override
            public void mouseClicked(MouseEvent e)
            {
                Point p = txt.getLocationOnScreen();
                p.y += 30;
                keyboard.setLocation(p);
                keyboard.setVisible(true);
            }
        });
        setLayout(new FlowLayout());
        add(txt);

        pack();
        setLocationByPlatform(true);
    }

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

    private class PopUpKeyboard extends JDialog implements ActionListener
    {
        private JTextField txt;

        public PopUpKeyboard(JTextField txt)
        {
            this.txt = txt;
            setLayout(new GridLayout(3, 3));
            for(int i = 1; i <= 9; i++) createButton(Integer.toString(i));
            pack();
        }

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

        @Override
        public void actionPerformed(ActionEvent e)
        {
            String actionCommand = e.getActionCommand();
            txt.setText(txt.getText() + actionCommand);
        }
    }
}

Answer 3

/**
 * @param args
 */
public static void main(String[] args) {
    // TODO Auto-generated method stub

    String alphabet = "abcdefghijklmnopqrstuvwxyz";

    JFrame myFrame = new JFrame();
    JPanel myPanel = new JPanel();

    for (int i = 0; i < alphabet.length(); i++) {

        myPanel.add(new JButton(alphabet.substring(i, i + 1)));
    }

    myFrame.add(myPanel);
    myFrame.pack();
    myFrame.setVisible(true);

}

This is a fast example of how to do it :).