Win a copy of 97 Things Every Java Programmer Should Know this week in the Java in General forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
  • Campbell Ritchie
  • Paul Clapham
  • Jeanne Boyarsky
  • Junilu Lacar
  • Henry Wong
  • Ron McLeod
  • Devaka Cooray
  • Tim Cooke
Saloon Keepers:
  • Tim Moores
  • Stephan van Hulst
  • Frits Walraven
  • Tim Holloway
  • Carey Brown
  • Piet Souris
  • salvin francis
  • fred rosenberger

java.lang.reflect.InvocationTargetException while loading a signed jar

Posts: 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I am trying to take a screenshot of the desktop and upload/save it somewhere. Sample code looks like this. The java file is
public class ScreenShot extends Applet
ScreenShotThread t = new ScreenShotThread();
public void init()

public boolean mouseDown(Event e,int x, int y)
return true;

The thread class looks like this:
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;

public class ScreenShotThread extends Thread
String request = "xxxx";
public void run()
Dimension d=Toolkit.getDefaultToolkit().getScreenSize();
Robot screenshot = new Robot();
BufferedImage screenImage = screenshot.createScreenCapture(new
sendBufferedImage(request, screenImage);
catch (Exception e)

public void sendBufferedImage(String urlpath, BufferedImage screenImage) throws
URL url = new URL(urlpath);
URLConnection urlcon = url.openConnection();
OutputStream out = urlcon.getOutputStream();
ImageIO.write(screenImage, "jpg", out);

Out of these, I have created a jar file which consists of only one class file, that of the applet i.e, "ScreenShot". I have signed the jar file and included it in a HTML for invoking like this

<applet code="ScreenShot.class" archive="ScreenShot.jar"/>

When I run the html, I get the security warnings, and once I accept to the risk, I get this error. "java.lang.reflect.InvocationTargetException". What I observed is, this error is not originating from within the code I have written, since I could not see any SOPs I used in the above files on the java console.
The interesting part is, if I didn't sign my applet, then I get a security exception at initialization of the robot class in the ScreenShotThread class.

Appreciate any help.

Posts: 1051
Hibernate Eclipse IDE Chrome
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
An InvocationTargetException usually wraps the underlying problem. Can you post the full stacktrace?
She's out of the country right now, toppling an unauthorized dictatorship. Please leave a message with this tiny ad:
Devious Experiments for a Truly Passive Greenhouse!
    Bookmark Topic Watch Topic
  • New Topic