layoutmanagerex.java

Graphical user interface example from class 2006

package layout;

import java.awt.*;		// needed for layout managers
import javax.swing.*;
public class LayoutManagerEx extends JPanel {
	private static final long serialVersionUID = 934392830372584926L;
	private static final int FRAME_WIDTH = 300;
	private static final int FRAME_HEIGHT = 400;
	private static final int XCOORD = 100;
	private static final int YCOORD = 200;
	private JFrame frame;
	private String title = "Layout Manager Example";
	private JButton[] jButtonArray;
	private enum LayoutManager {Flow, Grid};
	private LayoutManager manager = LayoutManager.Grid;
	
	public LayoutManagerEx() {
		frame = new JFrame();
		frame.setContentPane(this);
		frame.setLocation(XCOORD, YCOORD);
		frame.setSize(new Dimension(FRAME_WIDTH, FRAME_HEIGHT));
		frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
		frame.setTitle(title);	
		
		/* Determining which layout to use */
		int horizontalGap, verticalGap;
		switch (manager) {
		case Flow:
			// Left to right and row by row
			int alignment = FlowLayout.CENTER;
			horizontalGap = 40; verticalGap = 20;
			setLayout(new FlowLayout(alignment, horizontalGap, verticalGap));
			break;
		case Grid:
			// Matrix with specifies number of rows and columns
			// Number of rows is dominating factor
			// If one (rows or columns) is 0 the non-zero will be fixed
			int rows = 2, columns = 4;
			horizontalGap = 40; verticalGap = 20;
			setLayout(new GridLayout(rows, columns, horizontalGap, verticalGap));
			break;
		}
		
		/* Adding a a set of buttons */
		jButtonArray = new JButton[10];
		for (int i=0; i<jButtonArray.length; i++)
			jButtonArray[i] = new JButton("Button" + (i+1));
		
		for (JButton j : jButtonArray) 
			add(j);
		
		frame.setVisible(true);
		frame.pack();
	}
	
	public static void main(String[] args) {
		javax.swing.SwingUtilities.invokeLater(new Runnable() {
			public void run() {
				new LayoutManagerEx();
			}
		});
	}
}