Java Swing Layout

Question

I would like the following lay out...

• JButtons on top along side eachother.
• The JTextArea should be under the buttons.

• The JTextArea should also have a scrollbar.
  ...for the code below.

  JPanel jp = new JPanel();   
  One = new JButton("One");   
  Two = new JButton("Two");    
  TestOutput = new JTextArea();
  
  jp.add(One);
  jp.add(Two);
  jp.add(TestOutput);
  

Answer 1

The keyword is layering - having JPanel on JPanel.

Answer 2

The FlowLayout in a JPanel for the JButton instances is one way to go. You might also use a JToolBar for the buttons.

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

class ButtonsAndTextAreaLayout {

    ButtonsAndTextAreaLayout() {
        JPanel gui = new JPanel(new BorderLayout(5,5));

        // use a toolbar for the buttons
        JToolBar tools = new JToolBar();
        // use firstWordLowerCase for attribute/method names.
        JButton one = new JButton("One");
        JButton two = new JButton("Two");

        tools.add(one);
        tools.add(two);

        // provide hints as to how large the text area should be
        JTextArea testOutput = new JTextArea(5,20);

        gui.add(tools, BorderLayout.NORTH);
        gui.add(new JScrollPane(testOutput), BorderLayout.CENTER);

        JOptionPane.showMessageDialog(null, gui);
    }

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

Answer 3

Use a nested layout: To a JPanel having BorderLayout,

• add a JPanel having FlowLayout for the buttons to the NORTH
• and a JScrollPane for the JTextArea to the CENTER.

Answer 4

Use a GridBagLayout

See this for more help : How to Use GridBagLayout

Now note that the JTextarea to have a scrollbar have nothing to do with layouts.

See this for more help in that context : How to Use Scroll Panes

Answer 5

You can either use a GridBagLayout as suggested, or nest multiple layout managers such as:

JFrame frame = new JFrame();
frame.setLayout(new BorderLayout());

JPanel buttonPanel = new JPanel();
JButton oneButton = new JButton("One");
JButton twoButton = new JButton("Two");
buttonPanel.add(oneButton);
buttonPanel.add(twoButton);

JTextArea output = new JTextArea();
JScrollPane scrollPane = new JScrollPane(output);

frame.add(buttonPanel, BorderLayout.NORTH);
frame.add(scrollPane);
frame.pack();
frame.setVisible(true);