Class A extends B- where is paintComponent(Graphics) supposed to paint?

Question

Hi,
i have the following problem: I thought ControlPanel.paintComponent(Graphics) was supposed to paint the GraphArea (since ConrolPanel.paintComponent(Graphics) overrides GraphAreaExtension.paintComponent(Graphics) ), but lines AND vertices appear on the ControlPanel. Any ideas?
import ...
public class GraphAreaExtension extends JPanel
    public int clickCounter;  //how many clicks have been performed, ie
                                //how many vertices have been painted
    public int clickedX;
    public int clickedY;
    public Point[] darray;
    public GraphAreaExtension()
        setBorder(BorderFactory.createTitledBorder("Graph Area"));
        setPreferredSize(new Dimension(640, 450)); 
        setMaximumSize(new Dimension(640, 450));
        clickCounter=0;
        darray=new Point[8];
        clickedX=-50;
        clickedY=-50;      
        initializeDarray();
        addMouseListener(new MouseAdapter()
           public void mouseClicked (MouseEvent e)
                clickCounter++;
                if (clickCounter<=8)
                    clickedY=e.getY();               
                    clickedX=e.getX();
                    darray[clickCounter-1]=new Point(clickedX, clickedY);
                    System.out.print("Click counter "+clickCounter+" ");                   
                    System.out.println("Mouse clicked X: "+clickedX+" Y:"+clickedY);
                    repaint();
                    validate();
    }//GraphAreaExtension constructor
    public void paintComponent(Graphics g)
        System.out.println("paint vertex...");
        g.drawOval(clickedX,clickedY, 25,25);
        g.drawString(getVertexName(clickCounter),clickedX+11, clickedY+15);
        printDarray();
    private static String getVertexName(int num)
        num=num+96;
        char c=(char)num;
        String s=String.valueOf(c);
        return s.toUpperCase();
    private void initializeDarray()
        for (int i=0; i<darray.length; i++)
            darray=new Point(0,0);
public void printDarray()
for (int i=0; i<darray.length;i++)
System.out.print(darray[i].getX()+"\t");
System.out.println();
for (int i=0; i<darray.length;i++)
System.out.print(darray[i].getY()+"\t");
System.out.println();
import ...
/*  This is the Control Panel. 3 kinds of visual objects exist here:
*  -the JCheckBoxes, which indicate the incoming connections: in1-in8
*  -the JCheckBoxes, which indicate the outcoming connections: out1-out8
*  -the "Enter" button, which when pressed updates the in/out-coming
*   connections -graphically designs the edges, between the vertices.
*  The data taken from the in/out-coming JCheckBoxes are stored inside
*  2 boolean arrays respectively: inCon and outCon.
public class ControlPanel extends GraphAreaExtension implements ItemListener
    JPanel controlPanel;
    JButton jb;
    boolean[] inCon;
    boolean[] outCon;
    JCheckBox in1, in2, in3, in4, in5, in6, in7, in8;
    JCheckBox out1, out2, out3, out4, out5, out6, out7, out8;
    public ControlPanel()
        inCon= new boolean[8];
        outCon= new boolean[8];
        initializeBooleanTable(inCon);
        initializeBooleanTable(outCon);             
        setPreferredSize(new Dimension(800,150));
        setBackground(Color.LIGHT_GRAY);                  
        setBorder(BorderFactory.createTitledBorder("Connections"));
        setPreferredSize(new Dimension(120, 150));                   
        setMaximumSize(new Dimension(120, 150));
        JLabel in= new JLabel("Incoming connections");
        add(in);
        in1=new JCheckBox("A");
        in1.addItemListener(this);
        add(in1);
        in4=new JCheckBox("D");
        in4.addItemListener(this);
        add(in4);
        in8=new JCheckBox("H");
        in8.addItemListener(this);
        add(in8);
        JLabel out= new JLabel("Outcoming connections");
        add(out);          
        out1=new JCheckBox("A");
        add(out1);      
        out1.addItemListener(this);
        out3=new JCheckBox("C");           
        add(out3);  
        out3.addItemListener(this);
        out8=new JCheckBox("H");           
        add(out8);      
        out8.addItemListener(this);
        initializeCheckbox();
       /*  pressing the Enter button, the data concerning the connections,
        *  which the user has entered are transformed into edges between the
        * vertices.
        *  Incoming edges: Green and Outcoming: Red
        jb= new JButton("Enter");
        add(jb);
        jb.addActionListener(new ActionListener()
            public void actionPerformed(ActionEvent e)
                printConnectionArrays();
                repaint();
                validate();
    }//ControlPanel constructor
    public void paintComponent(Graphics g)
        System.out.println("paint edge...");
        for (int i=0; i<darray.length; i++)
            if (inCon==true)
System.out.println("Entered incoming edges condition for node num "+ (i+1));
g.drawLine(clickedX,clickedY,(int)darray[i].getX(), (int)darray[i].getY());
System.out.println("baseX "+clickedX+" baseY "+clickedY+" destX "+(int)darray[i].getX()+" destY "+(int)darray[i].getY());
g.setColor(Color.GREEN);
if (outCon[i]==true)
System.out.println("Entered outcoming edges condition for node num "+ (i+1));
g.drawLine(clickedX, clickedY,(int)darray[i].getX(), (int)darray[i].getY());
System.out.println("baseX "+clickedX+" baseY "+clickedY+" destX "+(int)darray[i].getX()+" destY "+(int)darray[i].getY());
g.setColor(Color.RED);
}//END for
initializeCheckbox();
initializeBooleanTable(inCon);
initializeBooleanTable(outCon);
/******************************Helper***Functions***************************/
/* unchecks Checkboxes for next use
public void initializeCheckbox()
in1.setSelected(false); out1.setSelected(false);
in8.setSelected(false); out8.setSelected(false);
public void itemStateChanged(ItemEvent e)
System.out.println("Entered ItemStateChanged()...");
Object source = e.getItemSelectable();
if (source.equals(in1)) inCon[0]=true;
else if (source.equals(in2)) inCon[1]=true;
else if (source.equals(in8)) inCon[7]=true;
if (source.equals(out1)) outCon[0]=true;
else if (source.equals(out2)) outCon[1]=true;
else if (source.equals(out8)) outCon[7]=true;
public void printConnectionArrays()
System.out.print("Incoming ");
for (int i=0; i<darray.length; i++)
System.out.print(inCon[i]+" ");
System.out.print("Outcoming ");
for (int i=0; i<darray.length; i++)
System.out.print(outCon[i]+" ");
System.out.println();
public static void initializeBooleanTable(boolean[] t)
for (int i=0; i<t.length-1; i++)
t[i]=false;

Answer 1

I've not a clue which is faster, but from an OO point of view--the object should know how to draw itself.