Run Time error

[Aroma Karim]

[color=darkred]

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Adition1 extends JFrame implements ActionListener{
	Container c;
	JLabel nr1,nr2,resultl;
	JButton add;
	JTextField nr11,nr22,resultt;
	public Adition1(){
		super("Adition");
		c= getContentPane();
		//c.setLayout(null);
		nr1= new JLabel("First Number :");
		nr1.setBounds(20,20,100,20);
		nr11=new JTextField();
		nr11.setBounds(140,20,100,20);
		nr2= new JLabel("Second Number :");
		nr2.setBounds(20,60,100,20);
		nr22=new JTextField();
		nr22.setBounds(140,60,100,20);
		resultl= new JLabel("Result:");
		nr1.setBounds(20,100,100,20);
		nr11=new JTextField(15);
		nr11.setBounds(140,100,100,20);
		add = new JButton ("Adition");
		add.setBounds(80,140,100,20);
		add.addActionListener(this);
		c.add(nr1);c.add(nr11);c.add(nr2);c.add(nr22);c.add(resultl);
		c.add(resultt);c.add(add);
		setSize(300,300);
		setVisible(true);
	}
	public void actionPerformed(ActionEvent e){
		float x,y;
		if(e.getSource()==add){
			x=Float.parseFloat(nr1.getText());
			y=Float.parseFloat(nr2.getText());
			resultt.setText(Float.toString(x+y));
		}
	}

public static void main(String args[]){
	new Adition1(); 
}
}

[/color]



the ERROR IS IN RUN TIME

Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Container.java:1039)
at java.awt.Container.add(Container.java:363)
at Adition1.<init>(Adition1.java:29)
at Adition1.main(Adition1.java:43)

[Jeff Verdegan]

A couple of suggestsions:

1. Don't use a lot of color. It makes your post hard to read. You tried to make the whole thing dark red. Fortunately, you didn't use the tags right, so it didn't work.

2. Put only one statement on a line. This is bad:

   c.add(resultt);c.add(add);  

3. Don't name variables the same as methods. Calling add(add) is confusing. Variable names should be nouns (things) or at least noun-ish. Method names should be verbs (actions).

If the line 29 it's complaining about matches the line 29 in the code you posted, then it's the one I mentioned in my point #2 above. Since the error is occurring inside Container.add(), and not on line 29 directly, we know that c is not null. So either resultt (also a confusing name) must be null or the "add" variable must be null. Possibly both.

[fred rosenberger]

You will also find that you get much more help here if you actually ask a question. Simply posting 45 lines of code and an error you got turns a lot of folks off. It looks like you don't feel it important enough to spend the time to formulate a real question, so many folks will not find it important enough to compose a reply.

[Ivan Franko]

Take a look at line 29:

c.add(resultt);

Variable resultt - what is this?

[Aroma Karim]

Ivan Franko wrote:Take a look at line 29:

c.add(resultt);

Variable resultt - what is this?

it's a JTextField variable!!

[Henry Wong]

Aroma Karim wrote:

Ivan Franko wrote:Take a look at line 29:

c.add(resultt);

Variable resultt - what is this?

it's a JTextField variable!!

And is the JTextField variable actually pointing to a JTextField object??