About paintComponent method

Question

Hello,
I am using swing to develop an user interface for a medium-complex program. Here is the code in the paintComponent method:
public void paintComponent (Graphics g) {
        Graphics2D g2 = (Graphics2D)g;
        super.paintComponents(g2);
        if (frame.m == null)
            System.out.println("Es null main");
        else {
            System.out.println("No es null main");
           Vector clusters = frame.m.obtenerClusters();
            Iterator it = clusters.iterator();
            while (it.hasNext()) {
                Cluster c = (Cluster)it.next();
                Punto p = c.obtenerCoordinador();
                Color color = c.obtenerColor();
                Vector sen = c.obtenerSensores();
                Iterator itS = sen.iterator();
                while (itS.hasNext()) {
                   Sensor s = (Sensor)itS.next();
                   dibujarSensor(g2, s, color);
                if (p != null) {
                    dibujarCoordinador(g2, p, color);
                    if (frame.isSelectedDibujarCirculo()) {
                        dibujarCirculoMinimo(g2, c.obtenerCoordinador(), c.obtenerRadio(), color);
            NodoSink s = frame.m.obtenerSink();
            if (s != null) {
              dibujarSink(g2,s);
    }Every time that this method is called (by me using repaint() or by the virtual machine), the program needs to "walk" over the hole Vector structure and paint again and again the same things, which is very inefficient.
There are some way to avoid it? I'm worry about it because the Vector structure is commonly very long.
Thanks!

Answer 1

Create a BufferedImage and do the custom painting on the BufferedImage.
If your painting is relatively static then you could create an ImageIcon from the BufferedImage and add the icon to a label and add the label to the GUI. If you need to change the custom painting then you would need to recreate the icon and update the image.
If you painting is relatively dynamic, then you just change the paintComponent() method to draw the buffered image.