Why the graphics doesn't show on screen?

Question

I wrote the code using AWT to draw an Arc2D to window after received input numbers but it draws nothing to screen. I tried to debug and found nothing. Can someone help me on this?
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
public class PieChart extends JFrame implements ActionListener
private JPanel inputP;
private DrawPanel drawP;
private JLabel instruct, prompt1, prompt2, prompt3, prompt4; //all prompt labels
private JTextField num1, num2, num3, num4; //input text field
int value1, value2, value3, value4, total;
//Graphics2D g2d;
public PieChart()
super( "Drawing 2D PieChart" );
Container c = getContentPane();
c.setLayout(new FlowLayout());
     inputP = new JPanel();
inputP.setLayout(new GridLayout(4,2));
                                                                                //initial text prompts
instruct = new JLabel("Enter the number at each prompt and press enter");
     prompt1 = new JLabel("First Number:");
prompt2 = new JLabel("Second Number:");
     prompt3 = new JLabel("Third Number:");
prompt4 = new JLabel("Fourth Number:");
                                                                                //initial input fields
num1 = new JTextField(5);
     num1.addActionListener(this);
     num2 = new JTextField(5);
     num2.addActionListener(this);
     num3 = new JTextField(5);
     num3.addActionListener(this);
     num4 = new JTextField(5);
     num4.addActionListener(this);
     inputP.add(prompt1);
     inputP.add(num1);
     inputP.add(prompt2);
     inputP.add(num2);
     inputP.add(prompt3);
     inputP.add(num3);
     inputP.add(prompt4);
     inputP.add(num4);
     c.add(inputP, BorderLayout.NORTH);
drawP = new DrawPanel(350,180);
drawP.add(instruct);
c.add(drawP, BorderLayout.CENTER);
setSize( 350, 560 );
show();
public void actionPerformed(ActionEvent e)
          String getInput;
          if(e.getSource() == num1)
               getInput = num1.getText();
               value1 = Integer.parseInt(getInput);
num2.grabFocus();
          if(e.getSource() == num2)
               getInput = num2.getText();
               value2 = Integer.parseInt(getInput);
num3.grabFocus();
          if(e.getSource() == num3)
               getInput = num3.getText();
               value3 = Integer.parseInt(getInput);
               num4.grabFocus();
          if(e.getSource() == num4)
               getInput = num4.getText();
               value4 = Integer.parseInt(getInput);
               drawP.setPie(value1, value2, value3,value4);
The main function will generate the new PieChart object and Overridden so we can exit when window is closed.*********************/
public static void main( String args[] )
PieChart app = new PieChart();
app.addWindowListener(
new WindowAdapter() {
public void windowClosing( WindowEvent e )
System.exit( 0 );
}//endmain
class DrawPanel extends JPanel {
//private int currentChoice = -1; // don't draw first time
private int width = 100, height = 100;
private int vl1, vl2, vl3, vl4, total ;
Graphics2D g2d;
public DrawPanel( int w, int h )
width = ( w >= 0 ? w : 100 );
height = ( h >= 0 ? h : 100 );
public void paintComponent( Graphics g )
super.paintComponent( g );
// create 2D by casting g to Graphics2D
g2d = ( Graphics2D ) g;
if(total == 0 )
g2d.setPaint(Color.black);
g2d.setStroke(new BasicStroke(1.0f));
g2d.draw(new Arc2D.Double(250,90,80,100,0,360,Arc2D.PIE));
System.out.print("Done drawing a cirle");
}else // draw 2D pie-shaped arc in white
g2d.setPaint( Color.cyan );
g2d.setStroke( new BasicStroke( 2.0f ) );
g2d.fill(new Arc2D.Double(120,90,80,100,0,(vl1*360/total),Arc2D.PIE));
g2d.setPaint( Color.blue );
g2d.setStroke( new BasicStroke( 2.0f ) );
g2d.fill(new Arc2D.Double(120,90,80,100,(vl1*360/total),(vl2*360/total),Arc2D.PIE));
g2d.setPaint( Color.green );
g2d.setStroke( new BasicStroke( 2.0f ) );
g2d.fill(new Arc2D.Double(120,90,80,100,(vl2*360/total),(vl3*360/total),Arc2D.PIE));
g2d.setPaint( Color.red );
g2d.setStroke( new BasicStroke( 2.0f ) );
g2d.fill(new Arc2D.Double(120,90,80,100,(vl3*360/total),(vl4*360/total),Arc2D.PIE));
System.out.print("End of drawing ");
public void setPie( int v1, int v2, int v3, int v4 )
total = 0;
vl1 = v1;
vl2 = v2;
vl3 = v3;
vl4 = v4;
total = v1 + v2 + v3 + v4;
System.out.print(v1+ " "+ v2+" "+v3+" "+v4+ " Total value: " + total);
repaint();
}

Answer 1

The first thing I see is the you have declared 'total' in DrawPanel. As it is never set there, you are testing a variable which is always zero.