I have just started learning java, and know only a small amount of code, however this is still a simple program. It is more of a prank program, but mostly just to test if I can make a jar file.
Here is the code:
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.util.Random;
public class randommouse {
public static void main(String[] args) {
for (int i=1; i<1000; i++) {
Random rand = new Random();
int w = rand.nextInt(1024) + 1;
int h = rand.nextInt(768) + 1;
int t = rand.nextInt(2000) + 1;
try {
Robot r = new Robot();
r.mouseMove(w,h);
Thread.sleep(t);
} catch (AWTException e) {}
catch (InterruptedException e) {}
catch (NullPointerException e) {}
}
}
}
I save this to file called randommouse.java
,
then compile it using
javac randommouse.java
This works and when I run it using
java randommouse
it works fine also.
So then I try to create a jar file. I use the command
jar cvf randommouse.jar randommouse.class
and it works. Afterwards I double click the jar file and it comes up with an error Java Exception
.
So then I run it in the cmd with
java -jar randommouse.jar
and get this error
F:Java>java -jar randommouse.jar
Exception in thread "main" java.lang.NullPointerException
at sun.launcher.LauncherHelper.getMainClassFromJar(LauncherHelper.java:3
99)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:463)
F:Java>
Do I need to put in an argument, and if so where do I put that in and how?
Thank you in advance
Sam
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