Thread: How to solve this exception ????

Hello every body I'm a new member in this very good website

I have just started to write java calculator and i face this run time exception

Exception in thread "main" java.lang.NullPointerException
at Calculater.<init>(Calculater.java:34)
at Calculater.main(Calculater.java:81)

and here is my code

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JTextArea;
import java.awt.FlowLayout;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Color;
 
public class Calculater extends JFrame
{
	public static final int WIDTH = 450;
	public static final int HIGHT = 250;
 
	public Calculater()
	{
		super("TextArea Calculater");
		setSize(WIDTH,HIGHT);
		setLocation(200, 200);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setVisible(true);
		setResizable(false);
		setLayout(new BorderLayout(5, 5));
 
		//Three Panel to orgenize the frame
		//leftPanel for numbers and operations
		JPanel leftPanel = new JPanel();
		leftPanel.setLayout(new GridLayout(4, 4, 5, 5));
		//rightPanel for the text area and the rest clear buttons
		JPanel rightPanel = new JPanel();
		rightPanel.setLayout(new BorderLayout(5, 5));
		//textAreaPanel for textArea
		JPanel textAreaPanel = new JPanel();
		textAreaPanel.setLayout(new GridLayout(1, 1, 5, 5));
		//clearsPanel for the all kind of clear buttons
		JPanel clearsPanel = new JPanel();
		clearsPanel.setLayout(new GridLayout(1, 3, 5, 5));
 
 
		//decleare buttons and add them to leftPanel
		JButton b1 = new JButton("7");
		leftPanel.add(b1);
		JButton b2 = new JButton("8");
		leftPanel.add(b2);
		JButton b3 = new JButton("9");
		leftPanel.add(b3);
		JButton b4 = new JButton("/");
		leftPanel.add(b4);
		JButton b5 = new JButton("4");
		leftPanel.add(b5);
		JButton b6 = new JButton("5");
		leftPanel.add(b6);
		JButton b7 = new JButton("6");
		leftPanel.add(b7);
		JButton b8 = new JButton("x");
		leftPanel.add(b8);
		JButton b9 = new JButton("1");
		leftPanel.add(b9);
		JButton b10 = new JButton("2");
		leftPanel.add(b10);
		JButton b11 = new JButton("3");
		leftPanel.add(b11);
		JButton b12 = new JButton("-");
		leftPanel.add(b12);
		JButton b13 = new JButton("0");
		leftPanel.add(b13);
		JButton b14 = new JButton(".");
		leftPanel.add(b14);
		JButton b15 = new JButton("=");
		leftPanel.add(b15);
		JButton b16 = new JButton("+");
		leftPanel.add(b16);
 
		//add leftPanel to the frame
		add(leftPanel, BorderLayout.CENTER);
 
		//decleare clears buttons and add them to clearPanel
		JButton b17 = new JButton("C");
		clearsPanel.add(b17);
		JButton b18 = new JButton("CE");
		clearsPanel.add(b18);
		JButton b19 = new JButton("Clear");
		clearsPanel.add(b19);
 
		//add clearPanel to rightPanel
		rightPanel.add(clearsPanel, BorderLayout.SOUTH);
 
		//declear text area and add it to textAreaPanel
		JTextArea myArea = new JTextArea();
		textAreaPanel.add(myArea);
 
		//add textAreaPanel to rightPanel
		rightPanel.add(textAreaPanel, BorderLayout.CENTER);
 
		//add rightPanel to the frame
		add(rightPanel, BorderLayout.EAST);
 
 
 
	}
	public static void main(String[] args)
	{
		Calculater myCalc = new Calculater();
	}
}

could any one help

System.out.println("Thank you.");

When posting code, please use the highlight tags. Unformatted code is very hard to read.

What line is that Exception occurring on? What are you trying to dereference? What is its value?

When posting code, please use the highlight tags. You can edit your original post to add them.

If that's the line, then it looks like content must be null. When do you declare and instantiate it?

There's a link in my signature explaining it, or you could look at the many other posts here that use them. But the point is, when posting code, you should surround it with highlight tags to preserve formatting. Unformatted code makes programmers' eyes bleed.

System.out.println("see how pretty this is?");