Thread: Easy - JTextArea won't get the text? and more stuff is wrong?

First of all , I'm new here
My name is Kasper and I'm new at java (want to learn it)
I'm from holland so my english isn't perfect.


so I've created a very basic program which can calculate the Easter date for each year.

this is the clas with the problem ( it's easy for you but for me it is hard (new at java))

package Pasen;
 
 
import java.awt.event.*;
 
import javax.swing.*;
 
 
public class PaasPaneel extends JPanel implements ActionListener
{
 
	private JTextField Jaartalveld;
	private JButton Bereken;
	private JTextArea uitkomstveld;
	int paasMaand;
	int paasDag;
	public String einddatum;
 
 
 
 
	public PaasPaneel()
	{
		JTextField Jaartalveld= new JTextField(4); // just doing basic stuff
		JButton Bereken = new JButton("Bepaal paasdatum");
		Bereken.addActionListener(this); // adds actionlistener to this JButton
		JTextArea uitkomstveld = new JTextArea(12, 35);
		add(new JLabel("Jaar"));
		add(Jaartalveld);
		add(Bereken);
		add(uitkomstveld);
	}
 
	/*
	 * This should calculate all the stuff
	 */
 
	public void JaartalTester(int beginJaartal)
	{
		System.out.println ("hoi");
		if (beginJaartal < 1900 || beginJaartal > 2099 )  // checks if the input is right
		{
			JOptionPane.showMessageDialog(   // show's this if the input is wrong
					null,
					"het jaartal moet tussen 1900 en 2099 zijn",  
					"Onjuist jaartal",
					JOptionPane.ERROR_MESSAGE);
		}
		else
		{
			int A = beginJaartal % 19;  // more calculation
			System.out.println(A); // debugging , same as below
			int B = beginJaartal % 4;
			System.out.println("dit is 2" + B);
			int C = beginJaartal % 7;
 
			int D = (19 * A + 24) % 30;
			int E = (5 + 2 * B + 4 * C + 6 * D) % 7;
			int F = D + E - 9;
			System.out.println("dit is " +F); // more debugging
 
			if (F > 0)
			{
				paasMaand = 4;
				System.out.println("waarde paasMaand = " + paasMaand);
				if (F == 26)
				{
					paasDag = 19;
				}
				else
				{
					if (F == 25 && D == 28)
					{
						paasDag = 18;
					}
					else
					{
						paasDag = F;
						System.out.println("hij komt hier");
					}
				}
			}
			else
			{
				paasMaand = 3;
				paasDag = F + 31;
 
			}
		}
 
		if (! (paasMaand <= 0 || paasDag <= 0))
		{
			einddatum =("in " + beginJaartal + "valt pasen op de dag " + paasDag + "van maand " + paasMaand); // gives the String "einddatum" a value
			System.out.println(einddatum);
			uitkomstveld.setText(einddatum); // this should set the value of "uitkomstveld" to "einddatum" but it doesn't work yet.
		}
 
 
 
	}
 
 
 
 
 
	public void actionPerformed (ActionEvent e)
	{
		int beginJaartal = 2007; //random default value
		 // Integer.parseInt(Jaartalveld.getText()); this should create a String which contains the text of "jaartalveld" but it doesn't work right know.	
		System.out.println("het beginjaartal is " + beginJaartal); //some debugging
		JaartalTester(beginJaartal); // calls the method JaartalTester
 
 
	}
 
 
}

when I run this program the console is like this:

het beginjaartal is 2007
hoi
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at Pasen.PaasPaneel.JaartalTester(PaasPaneel.java:95)
	at Pasen.PaasPaneel.actionPerformed(PaasPaneel.java:111)
12
dit is 23
dit is 8
waarde paasMaand = 4
hij komt hier
in 2007valt pasen op de dag 8van maand 4
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.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$3.run(Unknown Source)
	at java.awt.EventQueue$3.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)

sorry I'm such a noob >.< but I really don't know what to do..

Hope you can help me !

thanks!

huh?

line 94 :

String einddatum = ("in " + beginJaartal + "valt pasen op de dag " + paasDag + "van maand " + paasMaand); // gives the String "einddatum" a value

line 95 + 96:

System.out.println(einddatum);
uitkomstveld.setText(einddatum); // this should set the value of "uitkomstveld" to "einddatum" but it doesn't work yet.

in line 94 I gave "einddatum" a value and in line 95 + 96 I said print einddatum and set the text of "uitkomstveld" to "einddatum".
what variable does not have a value at this point? I don't understand this?

EDIT: "einddatum" has a variable, if I print it out :

[in 2007 valt pasen op de dag 8 van maand 4]

and what's wrong with line 110? :

JaartalTester(beginJaartal); // calls the method JaartalTester

I don't understand this and this is very confusing for me :S.

it doesn't have a value at that point .. I think.. it's a JTextArea. Isn't it normal that it has no value at that point?

uitkomstveld.setText(einddatum);

So here I try to set the value of uitkomstveld to "einddatum" but it won't work.

well, the value is null

how do I fix that? what value do I have to give to a JTextArea ? no idea ..

thanks I'm so dumb thank you so much <3