nullpointerexception lwjgl.opengl.GL11.glClear(G11.java:576)

[hedphuq]

I've just started out with lwjgl using this tutorial but I keep getting a nullpointerexception in the first example.

java.lang.NullPointerException
       at org.lwjgl.opengl.GL11.glClear(GL11.java:576)
       at platformgame.Main.render(Main.java:53)
       at platformgame.Main.mainLoop(Main.java:42)
       at platformgame.Main.main(Main.java:67)

I don't understand why I keep getting this, because I use Netbeans and I have added the libraries to my project libraries (wich is supposed to add them to the classpath at compile-time). Anyone has a clue?

Here's the code, you never know it's usefull:

/*
 * Main.java
 *
 * Created on 23 februari 2006, 19:52
 */

package platformgame;
import bsh.*;
import org.lwjgl.input.Keyboard;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;
import org.lwjgl.LWJGLException;
import java.io.*;


/**
 *
 * @author Ruben
 */
public class Main{
    
    public static DisplayMode findDisplayMode(int width, int height, int bitDepth) throws LWJGLException{
        DisplayMode[] modes = Display.getAvailableDisplayModes();
        for (int i = 0; i < modes.length; i++) {
            if (modes[i].getWidth() == width && modes[i].getHeight() == height &&
                    modes[i].getBitsPerPixel() >= bitDepth && modes[i].getFrequency() <= 85) {
                try {
                    Display.setDisplayMode(modes[i]);
                } catch (LWJGLException e) {
                    e.printStackTrace();
                }
                return modes[i];
            }
        }
        return null;
    }
    
    public static void mainLoop() throws Exception {
        int frameCount = 0;
        while( true ) {
            render();
            Display.update();
            if ( frameCount > 10000 ) {
                break;
            }
            frameCount++;
        }
        cleanup();
    }
    
    public static void render() {
        GL11.glClear(GL11.GL_COLOR_BUFFER_BIT); // clear the screen
        GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // set the clear color to black
    }
    
    public static void cleanup() {
        Display.destroy();
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        try {
            findDisplayMode(600, 800, 8);
            mainLoop();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}

[hedphuq]

I've tried changing java.library.path, but I don't seem to have any succes, I keep getting UnsatisfiedLinkError.
I used this in commandline:

java -jar "C:\Documents and Settings\Ruben\java\PlatformGame\dist\PlatformGame.jar" -Djava.library.path="C:\Documents and Settings\Ruben\java\lwjgl\native\lwjgl.dll"

I used commandline because Netbeans didn't state the errors clear

[Odeamus]

I don't see a call to Display.create() anywhere. You need to call it before doing any opengl calls.

O.

[hedphuq]

I've added Display.create() now, but it doesn't fix the problem, have I added it at the right place?

/*
 * JXmlGui.java
 *
 * Created on 16 december 2005, 19:20
 */

package jxmlgui;

import bsh.EvalError;
import bsh.TargetError;
import java.io.IOException;
import javax.swing.JFrame;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;

/**
 *
 * @author Ruben
 */
public class JXmlGui {
    static XMLReader producer;
    static Handler consumer;
    
    static {
        try {
            //get an instance of the default XML parser class
            producer = XMLReaderFactory.createXMLReader();
        } catch(SAXException e) {
            error(e);
        }
        
        try {
            //get a consumer for the parser events
            consumer = new Handler();
            //set the contenthandler
            producer.setContentHandler(consumer);
            //set the errorhandler
            producer.setErrorHandler(consumer);
        } catch(Exception e) {
            //the consumer setup can produce errors
            error(e);
        }
    }
    
    /** parsing method */
    public static void parseFile(String file) {
        try {
            //parse the file
            producer.parse(file);
            //error when reading of file doesn't succeed
        } catch(IOException e) {
            error(e);
            //error from sax
        } catch(SAXException e) {
            error(e);
        }
    }
    
    /** default method for handling errors (needs work as you can see)*/
    public static void error(Exception e) {
        e.printStackTrace();
    }
    
    static Object init(String kind, Attributes atts) {
        String bla = new String("bla");
        return bla;
    }
    
    public static void main(String[] args) {
        System.out.println("loading..."); //just print something to see if it's actually working
        try {
            parseFile("gui.xml"); //parse the file
        } catch(Exception e) {
            error(e); //catch errors
        }
        //just some test for the beanshell interpreter
        try {
            new bsh.Interpreter().eval("print(\"bsh works\")");
        } catch ( TargetError e ) {
            System.out.println("The script or code called by the script threw an exception: " + e.getTarget() );
        } catch ( EvalError e2 )    {
            System.out.println("There was an error in evaluating the script:" + e2 );
        }
    }
}

It compiles without problems, but when I run it Netbeans says:

java.lang.NoClassDefFoundError: and
Exception in thread "main"
Java Result: 1

[Odeamus]

All I can say is that you pasted the wrong code?

O.

[hedphuq]

oops, I guess I opened the wrong project  :oops:

/*
 * Main.java
 *
 * Created on 23 februari 2006, 19:52
 */

package platformgame;
import bsh.*;
import org.lwjgl.input.Keyboard;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;
import org.lwjgl.LWJGLException;
import java.io.*;


/**
 *
 * @author Ruben
 */
public class Main{
    
    public static DisplayMode findDisplayMode(int width, int height, int bitDepth) throws LWJGLException{
        DisplayMode[] modes = Display.getAvailableDisplayModes();
        for (int i = 0; i < modes.length; i++) {
            if (modes[i].getWidth() == width && modes[i].getHeight() == height &&
                    modes[i].getBitsPerPixel() >= bitDepth && modes[i].getFrequency() <= 85) {
                try {
                    Display.setDisplayMode(modes[i]);
                } catch (LWJGLException e) {
                    e.printStackTrace();
                }
                return modes[i];
            }
        }
        return null;
    }
    
    public static void mainLoop() throws Exception {
        int frameCount = 0;
        while( true ) {
            render();
            Display.update();
            if ( frameCount > 10000 ) {
                break;
            }
            frameCount++;
        }
        cleanup();
    }
    
    public static void render() {
        GL11.glClear(GL11.GL_COLOR_BUFFER_BIT); // clear the screen
        GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // set the clear color to black
    }
    
    public static void cleanup() {
        Display.destroy();
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        try {
            Display.create();
        } catch (LWJGLException ex) {
            ex.printStackTrace();
        }
        try {
            findDisplayMode(600, 800, 8);
            mainLoop();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}

the error was the right one

[Odeamus]

Hmm... All I can say is that it seems to be a problem with your launch configuration. It worked for me. All I found was couple unused imports, but that's all.
You might want to change the

if ( frameCount > 10000 ) {
                break;
}

part to

if (Display.isCloseRequested()) {
                break;
}

And add a Thread.yield() there too at the end of the loop. Much better that way.

[hedphuq]

did you compile it with netbeans IDE (5.0)?
Anyway, could you show me the VM options you used to run it?

[Odeamus]

Yes, I did.

Go to project properties and there in the Libraries tab add the lwjgl jars to the compile list. Then at the Run tab add -Djava.library.path=<path to native dir> to the VM options field.

That's all I did.

I hope that helps.

O.

[Fool Running]

It compiles without problems, but when I run it Netbeans says:
java.lang.NoClassDefFoundError: and
Exception in thread "main"
Java Result: 1

It looks like you might have set up the project to try run starting with a class called "and." Try looking at your project settings.
Right-click on the project and go to properties. Look under the run item for the main class.

[hedphuq]

I checked, but it I've set the right main class in the properties.
I started a new project, copied the source-code, and deleted the old project, but the problem remains. Could this be a Netbeans bug?

The only "and" I can think of, is in the path to the lwjgl libraries.
Could it be something goes wrong there? It seems unlikely to me.

Ofcourse, there was a second "and", in this line:

-Djava.library.path=C:\Documents and Settings\Ruben\java\lwjgl\native

fixed with:

-Djava.library.path="C:\Documents and Settings\Ruben\java\lwjgl\native"

stupid mistake, but that means Netbeans doesn't check the input, and just ignores the part it doesn't understand :?

[Fool Running]

So did you get it working with that change? I couldn't tell if you are still having problems or not. :?

[hedphuq]

it's fixed now, thanks for your help!