SIMPLE APPLET GETTING RUNTIME ERRORS

Question

I can figure out why this applet will not work, here is the code:
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import javax.swing.*;
public class Convert extends Applet {
JTextField tCentigrade = new JTextField();
JLabel lCentigrade = new JLabel();
JLabel lEqual = new JLabel();
String Fahrenheit;
//Construct the applet
public Convert() {
tCentigrade.setText("45");
//Component initialization
private void jbInit() throws Exception {
this.setLayout(null);
tCentigrade.setText("");
tCentigrade.setBounds(new Rectangle(94, 135, 56, 24));
tCentigrade.addActionListener(new Convert_tCentigrade_actionAdapter(this));
lCentigrade.setFont(new java.awt.Font("Serif", 0, 16));
lCentigrade.setText("Centigrade");
lCentigrade.setBounds(new Rectangle(22, 130, 71, 32));
this.setVisible(true);
lEqual.setFont(new java.awt.Font("Serif", 0, 24));
lEqual.setText("=");
lEqual.setBounds(new Rectangle(171, 139, 34, 15));
this.add(lCentigrade, null);
this.add(tCentigrade, null);
this.add(lEqual, null);
void tCentigrade_actionPerformed(ActionEvent e) {
double F;
double C = Double.parseDouble(tCentigrade.getText());
F = ((9/5) * C) + 32;
Fahrenheit = Double.toString(F);
public void paint(Graphics g)
g.drawString(Fahrenheit,50,50);
class Convert_tCentigrade_actionAdapter implements java.awt.event.ActionListener {
Convert adaptee;
Convert_tCentigrade_actionAdapter(Convert adaptee) {
this.adaptee = adaptee;
public void actionPerformed(ActionEvent e) {
adaptee.tCentigrade_actionPerformed(e);
}

Answer 1

the error message, if anyone wants to know, was:
java.lang.NullPointerException: string is null
at sun.java2d.SunGraphics2D.drawString(SunGraphics2D.java:2584)
at Convert.paint(Convert.java:51)
at sun.awt.RepaintArea.paint(RepaintArea.java:177)
at sun.awt.motif.MComponentPeer.handleEvent(MComponentPeer.java:374)
at java.awt.Component.dispatchEventImpl(Component.java:3658)
at java.awt.Container.dispatchEventImpl(Container.java:1623)
at java.awt.Component.dispatchEvent(Component.java:3439)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)
at jva.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
you get it because the string you try to draw at Convert.paint(Convert.java:51) is null.