How to remove a simple body in JBox2D? - libgdx

Question

Whenever I try to destroy a body in JBox2D it always give me a NullPointerException, and I have checked online and they show various ways of doing it 'safely' which I don't understand. I was wondering if anyone could type up some simple pseudo code to show how you would destroy a body in Box2D. I am also using the LibGDX API as well.
Here is my code that I use:
public void render(float delta) {
if(bodiesContainer.size() > 0)
{
for(Body body:bodiesContainer)
{
world.destroyBody(body);
}
}
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
stage.act(delta);
stage.draw();
world.step(TIMESTEP, VELOCITYITERATIONS, POSITIONITERATIONS);
camera.update();
debugRenderer.render(world, camera.combined);
batch.begin();
batch.end();
}
public void show() {
// TODO Auto-generated method stub
batch = new SpriteBatch();
camera = new OrthographicCamera(Gdx.graphics.getWidth()/5, Gdx.graphics.getHeight()/5);
world = new World(new Vector2(0,0f), true);
debugRenderer = new Box2DDebugRenderer();
stage = new Stage();
particleCreator = new ParticleCreator(0, 0, 1);
particleCreator.destroyParticle(world, particleBody);
if (particleCreator == null)
{
System.out.println("true");
}
if (particleBody == null)
{
System.out.println("true particleBody");
}
if (particleBodyDef == null)
{
System.out.println("true particleBodyDef");
}
Gdx.input.setInputProcessor(new InputProcessor() {
#Override
public boolean touchUp(int arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
return false;
}
#Override
public boolean touchDragged(int arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
return false;
}
#Override
public boolean touchDown(int arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
return false;
}
#Override
public boolean scrolled(int arg0) {
// TODO Auto-generated method stub
return false;
}
#Override
public boolean mouseMoved(int arg0, int arg1) {
// TODO Auto-generated method stub
return false;
}
#Override
public boolean keyUp(int arg0) {
// TODO Auto-generated method stub
return false;
}
#Override
public boolean keyTyped(char arg0) {
// TODO Auto-generated method stub
return false;
}
#Override
public boolean keyDown(int keycode) {
switch(keycode) {
case Keys.SPACE:
break;
}
return false;
}
});
}
public class ParticleCreator
{
//Default constructor
public ParticleCreator()
{
}
public ParticleCreator(World world, BodyDef bodyDef, Body body, float position_x, float position_y, float particle_radius)
{
bodyDef = new BodyDef();
bodyDef.type = BodyType.DynamicBody;
bodyDef.position.set(position_x, position_y);
CircleShape circleShape = new CircleShape();
circleShape.setRadius(particle_radius);
FixtureDef fixtureDef = new FixtureDef();
fixtureDef.shape = circleShape;
fixtureDef.restitution = 0;
body = world.createBody(bodyDef);
body.createFixture(fixtureDef);
}
public void destroyParticle(World world, Body body)
{
world.destroyBody(body);
System.out.println("This Particle has been destroyed !!!");
}
}
The bodiesContainer is an ArrayList, and the particleBody is a JBox2D body i wish to destroy, but every time I press the space button it crashes and gives me a NullPointerException.