“append” text for JTextField

问题:

I'm trying to make a small application where U input ID (with help of JButton -from 0 to 9 - ) and then pass the number that have been pressed to putText-Method and then display it in JTextField-the problem is that every time I press new number the one I pressed before disapears:s . Could anyone help me with that pls?

public class IdPanel extends JPanel {

    private JTextField idField;
    private JLabel idLabel;

    public IdPanel() {

        setLayout(new GridBagLayout());

        setPreferredSize(new Dimension(500, 70));

        idField = new JTextField(20);
        idField.setFont(new Font("Serif", Font.PLAIN, 20));

        idLabel = new JLabel("Enter ID:");
        idLabel.setFont(new Font("Serif", Font.PLAIN, 20));

        GridBagConstraints gc = new GridBagConstraints();

        gc.gridx = 0;
        gc.gridy = 0;
        gc.insets = new Insets(9, 9, 9, 9);
        gc.anchor = GridBagConstraints.CENTER;
        add(idLabel, gc);

        gc.gridx = 1;
        gc.anchor = GridBagConstraints.CENTER;
        add(idField, gc);
    }

    public void putText(String number) {
        idField.setText(number);
    }
}

回答1:

try:

idField.setText(idField.getText()+number);

回答2:

with help of JButton -from 0 to 9 -

Here is an example with 9 buttons:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

public class CalculatorPanel extends JPanel
{
    private JTextField display;

    public CalculatorPanel()
    {
        Action numberAction = new AbstractAction()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
//              display.setCaretPosition( display.getDocument().getLength() );
                display.replaceSelection(e.getActionCommand());
            }
        };

        setLayout( new BorderLayout() );

        display = new JTextField();
        display.setEditable( false );
        display.setHorizontalAlignment(JTextField.RIGHT);
        add(display, BorderLayout.NORTH);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout( new GridLayout(0, 5) );
        add(buttonPanel, BorderLayout.CENTER);

        for (int i = 0; i < 10; i++)
        {
            String text = String.valueOf(i);
            JButton button = new JButton( text );
            button.addActionListener( numberAction );
            button.setBorder( new LineBorder(Color.BLACK) );
            button.setPreferredSize( new Dimension(50, 50) );
            buttonPanel.add( button );

            InputMap inputMap = button.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
            inputMap.put(KeyStroke.getKeyStroke(text), text);
            inputMap.put(KeyStroke.getKeyStroke("NUMPAD" + text), text);
            button.getActionMap().put(text, numberAction);
        }
    }

    private static void createAndShowUI()
    {
//      UIManager.put("Button.margin", new Insets(10, 10, 10, 10) );

        JFrame frame = new JFrame("Calculator Panel");
        frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        frame.add( new CalculatorPanel() );
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}