hi leute, wenn ich in dem folgenden code
eingebe, gibts diese exception
-----------
java.lang.NullPointerException
at CamPicturev01.CamPictureFenster.paintImage(CamPictureFenster.java:76)
at CamPicturev01.CamPictureFenster.actionPerformed(CamPictureFenster.java:93)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(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)
------------
Wenn ich das ohne Button abfrage mache und direkt in der paint()
aufrufe dann zeigt er mir das pic ohne probleme an.
Was beachte ich hier nicht?
g + dank im voraus duddel123
Code:
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
public class CamPictureFenster extends Frame implements WindowListener,KeyListener, ActionListener{
private Graphics g;
private Image img=null;
// Konstruktor
CamPictureFenster(){
super("CamPictureFenster");
Panel NorthPanel=new Panel(new FlowLayout());
Button button1= new Button("Zeige CamPic");
button1.addActionListener(this);
NorthPanel.add(button1);
add(NorthPanel, BorderLayout.NORTH);
addWindowListener((WindowListener) this);
addKeyListener((KeyListener) this);
this.setVisible(true);
this.setSize(400, 400);
// Fenster wieder schliessen.
addWindowListener( new WindowAdapter() {
public void windowClosing(WindowEvent event){
setVisible(false);
dispose();
System.exit(0);
}
}
);
}
public void paint(Graphics g){
}
public void paintImage(Graphics g){
g.drawImage(img,40,40,this);
}
/**
* In dieser Methode werden alle Events bezueglich
* der Buttons abgefragt und verwertet.
*/
public void actionPerformed(ActionEvent e) {
Object ob=e.getSource();
String text = e.getActionCommand();
if (text.equals("Zeige CamPic")){
img = getToolkit().getImage("c:/3.gif");
paintImage(g);
}
}
}
eingebe, gibts diese exception
-----------
java.lang.NullPointerException
at CamPicturev01.CamPictureFenster.paintImage(CamPictureFenster.java:76)
at CamPicturev01.CamPictureFenster.actionPerformed(CamPictureFenster.java:93)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(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)
------------
Wenn ich das ohne Button abfrage mache und direkt in der paint()
Code:
img = getToolkit().getImage("c:/3.gif");
g.drawImage(img,40,40,this);
Was beachte ich hier nicht?
g + dank im voraus duddel123