Aufruf einer Methode

[Ama]

Hauptklasse:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;

import javax.swing.*;
import javax.swing.*;

/**
 * 
 */

/**
 * @author Ama
 * 
 */
public class RSA extends JFrame implements ActionListener
{
	JPanel btn, textpanel, textpanel2,border2,Content1;
	JButton bt1, bt2;
	JLabel offen,prim, erg1, wan1, RSA, privat;
	JTextField privatText1,privatText2, offenText1, offenText2, prim1, prim2, erg, wan;
	Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
	int z = 2;
	Berechnung b1;
	
	public RSA(String name)
	{
		this.setTitle(name);
		this.setSize(600, 150);
		this.setResizable(false);
		this.setLocation((int)d.getHeight()/5, (int)d.getWidth()/6);
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);
		
		btn = new JPanel();
		bt1 = new JButton("Generate");
		bt2 = new JButton("Test");
		this.bt1.addActionListener(this);
		this.bt2.addActionListener(this);
		
		this.btn.setLayout(new FlowLayout());
		this.btn.add(bt1);
		this.btn.add(bt2);
		
		privat = new JLabel("Privat:");
		offen = new JLabel("Oeffentlich:");
		prim = new JLabel("Primzahl(1+2):");
		erg1 = new JLabel("Ergebnis:");
		wan1 = new JLabel("Wan:");
		RSA = new JLabel("RSA- Verschlüsselung");
		
		
		privatText1 = new JTextField("",20);
		privatText2 = new JTextField("",20);
		offenText1 = new JTextField("",20);
		offenText2 = new JTextField("",20);
		prim1 = new JTextField("0",20);
		prim2 = new JTextField("0",20);
		erg = new JTextField("",20);
		wan = new JTextField("",20);
		
		
		textpanel = new JPanel();
		this.textpanel.setLayout(new GridLayout(2,1));
		this.textpanel.add(privat);
		this.textpanel.add(privatText1);
		this.textpanel.add(privatText2);
		this.textpanel.add(offen);
		this.textpanel.add(offenText1);
		this.textpanel.add(offenText2);
		
		textpanel2 = new JPanel();
		textpanel2.setLayout(new GridLayout(1,1));
		this.textpanel2.add(prim);
		this.textpanel2.add(prim1);
		this.textpanel2.add(prim2);
		this.textpanel2.add(erg1);
		this.textpanel2.add(erg);
		this.textpanel2.add(wan1);
		this.textpanel2.add(wan);
		
		border2 = new JPanel();
		this.border2.setLayout(new BorderLayout());
		border2.add(textpanel2, BorderLayout.NORTH);
		
		
		
		Content1 = new JPanel();
		this.Content1.setLayout(new BorderLayout());
		this.Content1.add(btn, BorderLayout.SOUTH);
		this.Content1.add(textpanel, BorderLayout.NORTH);
		this.Content1.add(border2, BorderLayout.CENTER);
		
		this.getContentPane().setLayout(new BorderLayout());
		this.getContentPane().add(Content1, BorderLayout.CENTER);
		this.getContentPane().add(RSA, BorderLayout.NORTH);
		
		this.setVisible(true);
	}
	/**
	 * @param args
	 */
	public static void main(String[] args)
	{
		// TODO Auto-generated method stub
		new RSA("RSA-Verschluesselung");
	}
	@Override
	public void actionPerformed(ActionEvent e)
	{
		// TODO Auto-generated method stub
		if(e.getActionCommand().equals("Generate"))
		{
			//this.privatText1.setText(Integer.toString((int) (Math.random()*100+1)));
			//int p = Integer.parseInt(this.prim1.getText());
			//int q = Integer.parseInt(this.prim1.getText());
			//new Berechnung(p, q);
			b1.n_berechnung();
			
			
		}
		if(e.getActionCommand().equals("Test"))
		{
			/*
			primzahl1 = Integer.parseInt(this.prim1.getText());
			if (primzahl1 % z == 0) 
			{
			      System.out.println(primzahl1 + "ist keine Primzahl");
			}
			primzahl2 = Integer.parseInt(this.prim2.getText());*/
		}
	}

}

2te Klasse: Berechnung

/**
 * 
 */

/**
 * @author Ama
 *
 */
public class Berechnung
{
	int primzahl1;
	int primzahl2;
	int m;
	int n;
	static int d;
	int e;
	
	public int getPrimzahl1()
	{
		return primzahl1;
	}

	public void setPrimzahl1(int primzahl1)
	{
		this.primzahl1 = primzahl1;
	}

	public int getPrimzahl2()
	{
		return primzahl2;
	}

	public void setPrimzahl2(int primzahl2)
	{
		this.primzahl2 = primzahl2;
	}

	public Berechnung(int p, int q)
	{
		this.setPrimzahl1(p);
		this.setPrimzahl2(q);
		System.out.println(this.getPrimzahl1());
		System.out.println(this.getPrimzahl2());
	}
	

	public int n_berechnung()
	{
		// TODO Auto-generated method stub
		return n;
	}
}

Dritte Klasse => GenerateN extends Berechnung

/**
 * 
 */

/**
 * @author Ama
 *
 */
public class GenerateN extends Berechnung
{
	public GenerateN()
	{
		super(0,0);
		// TODO Auto-generated constructor stub
	}

	@Override
	public int n_berechnung()
	{
		// TODO Auto-generated method stub
		n = this.getPrimzahl1()*this.getPrimzahl2();
		System.out.println("Generate");
		return n;
	}
}

Meine Frage wie kann ich von der Hauptklasse die Methode "public int n_berechnung()" aufrufen?

Ich habe es mir so gedacht, dass ich eine statische Instanz auf die Klasse Berechnung hab und dann von dort aus die Methode aufrufe ==>
b1.n_berechnung();

nur funktioniert das iwie nicht!

bitte um Hilfe!

Grüße

Fehlermeldung:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at RSA.actionPerformed(RSA.java:123)
	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$1.run(Unknown Source)
	at java.awt.EventQueue$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(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.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)

 

[Miness]

Du hast im Konstruktor deiner Klasse RSA die Instanzvariable b1 gar nicht initialisiert, darum wird eine NullPointerException geworfen. Füge im Konstruktur einfach einmal folgende Zeile ein:

b1 = new Berechnung(1, 2);

EDIT: Code angepasst, der Konstruktur der Klasse Berechnung hat ja zwei Parameter. Mein Fehler.

 

[XHelp]

b1 wird nirgendswo instanziiert... da sollte irgendwo (vermutlich Konstruktor)

b1 = new Berechnung(1,2)

oder so stehen.

 

[Ama]

ah^^
ich glaub ich sollt heute mal ne pause einlegen^^

DANKE! das war der Fehler!