4.5 Implementing Your Own Icons

Here's a class that implements the Icon interface and uses ovals as simple icons:

// OvalIcon.java // import javax.swing.*; import java.awt.*; // A simple icon implementation that draws ovals public class OvalIcon implements Icon {   private int width, height;   public OvalIcon(int w, int h) {     width = w;     height = h;   }   public void paintIcon(Component c, Graphics g, int x, int y) {     g.drawOval(x, y, width-1, height-1);   }   public int getIconWidth( ) { return width; }   public int getIconHeight( ) { return height; } }

A simple class that creates a few labels shows how it works:

// TestOval.java // import javax.swing.*; import java.awt.*; public class TestOval {   public static void main(String[] args) {     JFrame f = new JFrame( );     f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);     JLabel label1 = new JLabel(new OvalIcon(20,50));     JLabel label2 = new JLabel(new OvalIcon(50,20));     JLabel label3 = new JLabel("Round!", new OvalIcon(60,60), SwingConstants.CENTER);     label3.setHorizontalTextPosition(SwingConstants.CENTER);     Container c = f.getContentPane( );     c.setLayout(new FlowLayout( ));     c.add(label1);     c.add(label2);     c.add(label3);     f.pack( );     f.setVisible(true);   } }

Running this test program produces the display shown in Figure 4-7.

Figure 4-7. OvalIcon labels