Android Studio Jbox2D java.lang.NoClassDefFoundError：org.slf4j.LoggerFactory

Question

I'm currently trying to implement some physics into my app, however I am running into a problem when compiling.

Compilation error:

01-18 18:38:49.165  32473-32473/com.example.anthonys.pennyhockey E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.anthonys.pennyhockey, PID: 32473
java.lang.NoClassDefFoundError: org.slf4j.LoggerFactory
        at org.jbox2d.pooling.normal.MutableStack.<clinit>(MutableStack.java:35)
        at org.jbox2d.pooling.normal.DefaultWorldPool.<init>(DefaultWorldPool.java:66)
        at org.jbox2d.dynamics.World.<init>(World.java:122)
        at com.example.anthonys.pennyhockey.Play.<init>(Play.java:52)
        at java.lang.Class.newInstanceImpl(Native Method)
        at java.lang.Class.newInstance(Class.java:1208)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2122)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
        at android.app.ActivityThread.access$800(ActivityThread.java:144)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5146)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
        at dalvik.system.NativeStart.main(Native Method)

my code:

package com.example.anthonys.pennyhockey;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

import org.jbox2d.collision.shapes.PolygonShape;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.Body;
import org.jbox2d.dynamics.BodyDef; 
import org.jbox2d.dynamics.BodyType;
import org.jbox2d.dynamics.FixtureDef;
import org.jbox2d.dynamics.World;


public class Play extends Activity {


private void definition()
{
    BodyDef penny = new BodyDef();
    penny.type = BodyType.DYNAMIC;
    penny.position.set(0,20);
    penny.angle = 0;
    Body myObject = world.createBody(penny);
    PolygonShape pennyShape = new PolygonShape();
    pennyShape.setAsBox(0.75f,0.75f);

    FixtureDef pennyFixture = new FixtureDef();
    pennyFixture.shape = pennyShape;
    pennyFixture.density = 1;
    myObject.createFixture(pennyFixture);

}









@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_play);
}


World world = new World(new Vec2(0, -9.8f), false);



@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.play, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

}

Basically I am trying to make a 2D figure that can be moved around. I'm quite new to Jbox2d so if anyone has any easier physics engines I could use, I would also be open to suggestion!

I have the jbox2d-library-2.1.2.2.jar file in a folder named 'libs'. I have added the following to the app build.gradle

    dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
compile files('libs/jbox2d-library-2.1.2.2.jar')
}

Answer 1

I don't know about jbox2d, but what happened is that sl4j (which is a logging facade ) could not find a logging implementation .

Probably all you need to do is providing one in you classpath, eg log4j

 compile 'org.slf4j:slf4j-log4j12:1.6.4'

(not sure about the exact version though)

BTW, jbox2d mentions this in its documentation ( "not building with maven" ) :)

EDIT : any reason you don't get the dependencies from a maven repo? Seems much easier to just get it from here and let gradle take care of the dependencies...

'org.jbox2d:jbox2d:2.1.2.2'