Problem with Java Classes, in an applet

**SashaThompson** · October 1st, 2011, 04:12 AM

Here is my main piece of code:

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
 
public class MiniMajorProject extends Applet implements KeyListener, ItemListener {
 
TextField OriginalText;
String politeForm;
boolean isPoliteForm, isPoliteFormpast, PresentisPoliteForm, isPast;
int len;
Checkbox checkbox1, checkbox2;
 
	PoliteForm politeObject = new PoliteForm();
 
public void init() {
	setLayout (null);
	OriginalText = new TextField();
	OriginalText.setBounds(200, 200, 100,35);
	add(OriginalText);
	OriginalText.addKeyListener(this);
 
	checkbox1 = new Checkbox("polite form present");
	checkbox1.setBounds(350,180,130,35);
	checkbox1.addItemListener(this);
	add(checkbox1);
 
	checkbox2 = new Checkbox("polite form past");
	checkbox2.setBounds(350,250,130,35);
	checkbox2.addItemListener(this);
	add(checkbox2);
 
}
 
public void itemStateChanged(ItemEvent e) {
    if (e.getSource() == checkbox1) {
    	len = politeForm.length();
		politeObject.polite();
    }
 
    if (e.getSource() == checkbox2){
    	if (politeForm.endsWith("iru")){
    		len = politeForm.length();
			isPast = true;
			isPoliteForm = false;
		}
 
		if (politeForm.endsWith("eru")){
			len = politeForm.length();
			isPast = true;
			isPoliteForm = false;
		}
    }
    } 
 
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER)
{
	politeForm = OriginalText.getText();
}
this.repaint(); //request a repaint
}//end KeyPressed()
 
public void paint(Graphics g)
{
	if (isPoliteForm)
	{
		g.drawString(politeForm.substring(0,(len -2)) + "masu", 250,300);
	}
 
	if (isPast)
	{
		g.drawString(politeForm.substring(0,(len -2)) + "mashita", 300,300);
	}
}//end paint()
 
public void keyReleased(KeyEvent e) { }
 
 
public void keyTyped(KeyEvent e) { }
 
}//end class

Here is the class PoliteForm:

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
 
public class PoliteForm {
	String politeForm;
	TextField OriginalText;
	boolean isPoliteForm, isPoliteFormpast, PresentisPoliteForm, isPast;
	int len;
 
	public void keyPressed(KeyEvent e) {
		if (e.getKeyCode() == KeyEvent.VK_ENTER)
		{
			politeForm = OriginalText.getText();
		}
	}
 
	public boolean polite(){
    	if (politeForm.endsWith("iru")){
    		len = politeForm.length();
			isPoliteForm = true;
			isPast = false;
		}
 
		if (politeForm.endsWith("eru")){
			len = politeForm.length();
			isPoliteForm = true;
			isPast = false;
		}
 
		return isPoliteForm;
	}
}

I can't use checkbox one as the program errors, I think it's because I wrote the class wrong..
Can anybody help and fix my problem?
Thankyou so much!

**Norm** · October 1st, 2011, 08:03 AM

the program errors,

Please copy and paste here the full text of the error message.

**SashaThompson** · October 1st, 2011, 05:19 PM

Originally Posted by Norm

Please copy and paste here the full text of the error message.

Error Message:
Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
at MiniMajorProject.itemStateChanged(MiniMajorProject .java:36)
at java.awt.Checkbox.processItemEvent(Unknown Source)
at java.awt.Checkbox.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(Unknown Source)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

**Norm** · October 1st, 2011, 05:23 PM

Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
at MiniMajorProject.itemStateChanged(MiniMajorProject .java:36)

At line 36 in MiniMajorProject there is a variable with a null value. Look at that line of code and see what variable is there that is null and then backtrack in your code to see why that variable does not have a valid value.

If you can't see which variable is null add a println to show the values of all the variables on that line.

**SashaThompson** · October 1st, 2011, 07:10 PM

Originally Posted by Norm

At line 36 in MiniMajorProject there is a variable with a null value. Look at that line of code and see what variable is there that is null and then backtrack in your code to see why that variable does not have a valid value.

If you can't see which variable is null add a println to show the values of all the variables on that line.

I found that variable, I deleted the variable len for the purpose of seeing if that got rid of the error and once I deleted it I got the same issue but it said no value was being assigned to politeObject.polite(), there is deffinitely a problem with the class I just can't see what though any ideas?

**Norm** · October 1st, 2011, 07:28 PM

there is deffinitely a problem with the class I just can't see what though

Please explain why you think there is a problem. Do you see an error message or bad output or what?

**SashaThompson** · October 1st, 2011, 08:04 PM

Originally Posted by Norm

Please explain why you think there is a problem. Do you see an error message or bad output or what?

I think there is an error with the object because it seems that no value is assigned to the object because it is coming up with the same error and that line is where the object is being called, also because I just am not very good with objects and classes so don't know if it is possible to transfer the word inputted in the textfield to the object class, where the object class then has a bunch of if statements which check the ending of the word and then returns a boolean value depending on the end of the word.
I don't know if it's actually possible!

**Norm** · October 1st, 2011, 08:07 PM

it is coming up with the same error

If you are getting a NullPointerException you need to track down why the variable does not have a valid value.

**Norm** · October 1st, 2011, 08:08 PM

Please edit your post, select the code and wrap it with code tags.
See:BB Code List - Java Programming Forums
Or press the Go Advanced and use the #icon

**SashaThompson** · October 1st, 2011, 08:50 PM

Originally Posted by Norm

Please edit your post, select the code and wrap it with code tags.
See:BB Code List - Java Programming Forums
Or press the Go Advanced and use the #icon

Hope I did it right!

**Norm** · October 1st, 2011, 08:51 PM

Yes, that is a lot easier to read and understand.
Have you found the null variable and then found out why it doesn't not have a valid value?

**SashaThompson** · October 1st, 2011, 09:35 PM

Originally Posted by Norm

Yes, that is a lot easier to read and understand.
Have you found the null variable and then found out why it doesn't not have a valid value?

I think the null variable is the boolean, isPoliteForm but I don't know why it doesn't have a valid value...

**Norm** · October 2nd, 2011, 07:15 AM

I think the null variable is the boolean

Primitive variables can not have null values. boolean is a primitive.
reference variables can have null values and that will cause the exception.

Add some printlns to print out the values of all the variables used on the statement where the error occurs so you can see which variable has a null value.

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