Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.Window;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

public class Main {
    public static void swapComponentsAndResizeUI(JComponent ui, JComponent current, JComponent next) {
        ui.remove(current);
        ui.add(next);
        current = next;
        Component c = ui.getTopLevelAncestor();
        if (c instanceof Window) {
            Window w = (Window) c;
            w.pack();
        }
    }

    public static void main(String[] args) {
        JPanel ui = new JPanel(new BorderLayout(4, 4));
        ui.setBorder(new EmptyBorder(6, 6, 6, 6));

        JPanel controls = new JPanel(new FlowLayout(FlowLayout.LEADING));
        ui.add(controls, BorderLayout.PAGE_START);
        int s = 100;
        Dimension[] sizes = { new Dimension(s * 4, s * 2), new Dimension(s * 6, s * 3),
                new Dimension(s * 8, s * 4) };
        final JComboBox cb = new JComboBox(sizes);
        controls.add(cb);
        final JPanel[] panels = new JPanel[sizes.length];
        for (int ii = 0; ii < sizes.length; ii++) {
            Dimension d = sizes[ii];
            BufferedImage bi = new BufferedImage(d.width, d.height, BufferedImage.TYPE_INT_RGB);
            JPanel p = new JPanel(new GridLayout());
            JLabel l = new JLabel(new ImageIcon(bi));
            p.add(l);
            panels[ii] = p;
        }
        ItemListener sizeListener = new ItemListener() {

            JPanel current = panels[0];

            @Override
            public void itemStateChanged(ItemEvent e) {
                JPanel next = panels[cb.getSelectedIndex()];
                swapComponentsAndResizeUI(ui, current, next);
                current = next;
            }
        };
        cb.addItemListener(sizeListener);

        ui.add(panels[0], BorderLayout.CENTER);

        JFrame f = new JFrame("Three Sized Panels");
        f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        f.setContentPane(ui);
        f.pack();
        f.setLocationByPlatform(true);
        f.setVisible(true);
    }
}