Repaint problems with canavses in JTabbedPane

Question

Basically I have a JTabbedPane with Canvases in the tabs, and when I select a tab I want the appropriate canvas to draw itself. At the moment I have a simple grid set up to be displayed, which appears on the selected canvas when I start the program, but then when I change tabs only flashes up briefly before disappearing. Heres the code, imports left out:
Creates the window
public class GUI {
     public static final int WIDTH=900;
     public static final int HEIGHT=600;
     public GUI() {
          JFrame frame = new JFrame("MapMaker");
          frame.setVisible(true);
          frame.setIgnoreRepaint(true);
          CanvasTab tabbedPane = new CanvasTab();
          MapCanvas mc1 = new MapCanvas();
          tabbedPane.addTab("Layer 1", mc1);
          MapCanvas mc2 = new MapCanvas();
          tabbedPane.addTab("Layer 2", mc2);               
          JPanel leftPanel = new JPanel();
          leftPanel.setBackground(Color.RED);
          leftPanel.setPreferredSize(new Dimension(200, HEIGHT));
          JPanel rightPanel = new JPanel();
          rightPanel.setBackground(Color.BLUE);
          rightPanel.setPreferredSize(new Dimension(WIDTH-200, HEIGHT));          
          rightPanel.add(tabbedPane, BorderLayout.CENTER);
          rightPanel.setIgnoreRepaint(true);
          frame.add(leftPanel, BorderLayout.WEST);
          frame.add(rightPanel, BorderLayout.EAST);     
          frame.pack();
          mc1.makeBuffers(2);
          mc1.drawContent();          
          mc2.makeBuffers(2);
          tabbedPane.addChangeListener(new TabChangeListener(tabbedPane));
     public static void main(String[] args) {
          GUI g = new GUI();
}The tabbed pane
public class CanvasTab extends JTabbedPane {
     public CanvasTab() {
          setIgnoreRepaint(true);
}The canvas
public class MapCanvas extends Canvas {
     private BufferStrategy strategy;
     public MapCanvas() {
          setPreferredSize(new Dimension(640, 480));
     public void drawGrid() {
          Graphics2D g = (Graphics2D) strategy.getDrawGraphics();
          g.setColor(Color.blue);
          for (int i=1; i<20; i++) {
               g.drawLine(i*32, 0, i*32, 480);
          for (int i=1; i<15; i++) {
               g.drawLine(0, i*32, 640, i*32);
     public void drawContent() {
          drawGrid();
          strategy.show();
     public void makeBuffers(int noBuffs) {
          createBufferStrategy(noBuffs);
          strategy = getBufferStrategy();
          setIgnoreRepaint(true);
}The change listener
public class TabChangeListener implements ChangeListener{
     private JTabbedPane tabPane;
     public TabChangeListener(JTabbedPane pane) {
          tabPane = pane;
     public void stateChanged(ChangeEvent e) {
          //doesn't work at all, this is the functionality I want eventually
                //get the tab just selected
          //MapCanvas c = (MapCanvas) tabPane.getSelectedComponent();
          //c.drawContent();
          //grid only flashes up for a split second
          MapCanvas c = (MapCanvas) tabPane.getComponent(0);
          c.drawContent();
          MapCanvas d = (MapCanvas) tabPane.getComponent(1);
          d.drawContent();
}Thanks

Answer 1

General rule is don't mix AWT component with Swing components.
Use a JComponent instead of a Canvas for custom painting.