Question

Please have a look the following code

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

public class GUI extends JFrame
{
    private JButton open, process;
    private JLabel center;
    private JScrollPane scroll;
    private Box box;
    private IplImage image;

    public FirstGUI()
    {
        open = new JButton("Open Image");
        open.setPreferredSize(new Dimension(70,20));
        open.setMaximumSize(new Dimension(100,20));

        open.addActionListener(new OpenImageAction());
        process = new JButton("Process");
        process.setPreferredSize(new Dimension(100,20));
        process.setMinimumSize(new Dimension(100,20));
        process.addActionListener(new ProcessAction());
        System.out.println("Open Size: "+open.getSize()+"      Process size: "+process.getSize());


        box = new Box(BoxLayout.Y_AXIS);
        box.add(open);
        box.add(process);

        center = new JLabel();
        scroll = new JScrollPane(center);

        getContentPane().add(box,"West");
        getContentPane().add(scroll,"Center");

        this.setSize(300,300);
        this.pack();
        this.validate();
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

    public static void main(String[]args)
    {
        try
        {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

            new GUI();
        }
        catch(java.lang.Exception e)
        {
            JOptionPane.showMessageDialog(null,"GUI Error");
        }
    }

I want to make all the buttons in same size. In here, first one is wider than the second one. I need same width ans hight for both. As you can see, I have used all the availables like setPrefferedSize(), setMaximumSize(), setMinimumSize(), but it is still not working properly. Please help!

Answer 1

Here is one way to achieve this using a GridLayout. I also introduced an additional JPanel so that the buttons are not stretched when the JFrame is resized and I chose the GridBagLayout for it so that it will center the button panel vertically. There are definitely other ways to solve your issue.

One thing you should try to avoid is to force preferred/maximum/minimum sizes. Delegate this to the L&F and the LayoutMananager’s.

If you call pack() on a JFrame, it is useless to set its size previously, as pack() will change that anyway. Try to make the call to setVisible(true); the last line of your GUI initialization.

If you want to understand properly how layout, positioning, sizing, etc… works in Swing, I would strongly recommend to read the tutorial on LayoutManager’s.

import java.awt.BorderLayout;
import java.awt.GridBagLayout;
import java.awt.GridLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

public class GUI extends JFrame {
    private JButton open, process;
    private JLabel center;
    private JScrollPane scroll;
    private JPanel box;

    public GUI() {
        open = new JButton("Open Image");
        // open.addActionListener(new OpenImageAction());
        process = new JButton("Process");
        // process.addActionListener(new ProcessAction());

        box = new JPanel(new GridLayout(2, 1));
        box.add(open);
        box.add(process);
        JPanel west = new JPanel(new GridBagLayout());
        west.add(box);

        center = new JLabel("Some center label");
        scroll = new JScrollPane(center);

        getContentPane().add(west, BorderLayout.WEST);
        getContentPane().add(scroll);

        this.pack();
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }

    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (java.lang.Exception e) {
            JOptionPane.showMessageDialog(null, "GUI Error");
        }
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new GUI();
            }
        });
    }
}