ayuda con capturar pantalla en java

[RIVERMILLOS]

hola tengo esta clase que captura la pantalla y la pone en un label , pero cuando va poner la segunda imagen me sale un error esta es la clase..

Código:

import java.awt.AWTException;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.Robot;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.*;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
 
class CapturarPantalla {
int x=1;
Main m;
public CapturarPantalla(Main m){
	this.m=m;
}
public int captura() throws HeadlessException, AWTException, IOException{
	
    BufferedImage pantalla = new Robot().createScreenCapture(
    new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()) );
    
    File file = new File("src/pantalla"+x+".jpg");
    ImageIO.write(pantalla, "jpg", file);
    ImageIcon tmpIconAux = new ImageIcon(getClass().getResource("src/pantalla"+x+".jpg"));
   mageIcon tmpIcon = new ImageIcon(tmpIconAux.getImage().getScaledInstance(950, -5, Image.SCALE_DEFAULT));
   this.m.label.setIcon(tmpIcon);
    this.m.label.validate();
  
    x++;
    return 1;
}	
public static void main(String args[]){
     
   }
}

main es otra clase que genera lo grafico.

Código:

public static void main(String arg[]){Main m=new Main();objeto= new CapturarPantalla(m)}

@Override
public void actionPerformed(ActionEvent arg0) {
try {
objeto.captura();
}catch (HeadlessException e) {
e.printStackTrace();
}catch (AWTException e) {
e.printStackTrace();
}catch (IOException e) {
e.printStackTrace();
}	
}

este es el error

Código:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at javax.swing.ImageIcon.<init>(Unknown Source)
	at CapturarPantalla.captura(CapturarPantalla.java:26)
	at Main.actionPerformed(Main.java:42)
	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.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)

que puede ser
saludos