nullpointerexception - Libgdx null Pointer -

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i´m working on box2d jump , run game , want player teleported start when hits spike, when hits spike, null pointer exception.

heres contact class:

public class worldcontactlistener implements contactlistener {  player player;  @override public void begincontact(contact contact) {     fixture fixa = contact.getfixturea();     fixture fixb = contact.getfixtureb();     player = new player();      int cdef = fixa.getfilterdata().categorybits | fixb.getfilterdata().categorybits;      switch (cdef) {         case hardwarerunner.player_bit | hardwarerunner.brick_bit:         case hardwarerunner.player_bit | hardwarerunner.spike_bit:             player.die();      } }

and heres part of player class:

public void defineplayer(){     bdef.position.set(32 / runner.ppm, (6 * 32) / runner.ppm);     bdef.type = bodydef.bodytype.dynamicbody;     b2body = world.createbody(bdef);      fixturedef fdef = new fixturedef();     polygonshape shape = new polygonshape();     vector2[] vertice = new vector2[4];     vertice[0] = new vector2(-13, 13).scl(1 / runner.ppm);     vertice[1] = new vector2(13, 13).scl(1 / runner.ppm);     vertice[2] = new vector2(13, -13).scl(1 / runner.ppm);     vertice[3] = new vector2(-13, -13).scl(1 / runner.ppm);     shape.set(vertice);     shape.getradius();     fdef.filter.categorybits = hardwarerunner.player_bit;     fdef.filter.maskbits =             hardwarerunner.ground_bit |             hardwarerunner.coin_bit |             hardwarerunner.brick_bit |             hardwarerunner.enemy_bit |             hardwarerunner.spike_bit |             hardwarerunner.enemy_head_bit |             hardwarerunner.item_bit;      fdef.shape = shape;     fdef.friction = .1f;     b2body.createfixture(fdef).setuserdata(this);     fdef.issensor = true;      b2body.createfixture(fdef).setuserdata(this); }  public void die() {     world.destroybody(b2body);      bdef.position.set(32 / runner.ppm, (6 * 32) / runner.ppm);     bdef.type = bodydef.bodytype.dynamicbody;     b2body = world.createbody(bdef);      fixturedef fdef = new fixturedef();     polygonshape shape = new polygonshape();     vector2[] vertice = new vector2[4];     vertice[0] = new vector2(-13, 13).scl(1 / runner.ppm);     vertice[1] = new vector2(13, 13).scl(1 / runner.ppm);     vertice[2] = new vector2(13, -13).scl(1 / runner.ppm);     vertice[3] = new vector2(-13, -13).scl(1 / runner.ppm);     shape.set(vertice);     shape.getradius();     fdef.filter.categorybits = hardwarerunner.player_bit;     fdef.filter.maskbits =             hardwarerunner.ground_bit |                     hardwarerunner.coin_bit |                     hardwarerunner.brick_bit |                     hardwarerunner.enemy_bit |                     hardwarerunner.spike_bit |                     hardwarerunner.enemy_head_bit |                     hardwarerunner.item_bit;      fdef.shape = shape;     fdef.friction = .1f;     b2body.createfixture(fdef).setuserdata(this);     fdef.issensor = true;      b2body.createfixture(fdef).setuserdata(this); }

and error is:

exception in thread "lwjgl application" java.lang.nullpointerexception @ de.tobls.hardwarerunner.sprites.player.die(player.java:223) @ de.tobls.hardwarerunner.tools.worldcontactlistener.begincontact(worldcontactlistener.java:27) @ com.badlogic.gdx.physics.box2d.world.begincontact(world.java:982) @ com.badlogic.gdx.physics.box2d.world.jnistep(native method) @ com.badlogic.gdx.physics.box2d.world.step(world.java:686) @ de.tobls.hardwarerunner.screens.playscreen.update(playscreen.java:112) @ de.tobls.hardwarerunner.screens.playscreen.render(playscreen.java:127) @ com.badlogic.gdx.game.render(game.java:46) @ de.tobls.hardwarerunner.hardwarerunner.render(hardwarerunner.java:71) @ com.badlogic.gdx.backends.lwjgl.lwjglapplication.mainloop(lwjglapplication.java:215) @ com.badlogic.gdx.backends.lwjgl.lwjglapplication$1.run(lwjglapplication.java:120)

can me?

first of should not destroy worlds items in asynchronous methods - notice contact listeners's methods asynchronous.

the proper way destroy body od mark , destroy right before world.update() 

    //in asynchronous method      body.setuserdata("destroy");      //when rendering     for(body body : world.getbodies())             if(body.getuserdata().equals("destroy")) world.destroybody(body);

but on top of - see doing nothing moving body when die why not use settransform method then

    body.settransform(new vector2(newx, newy), body.getangle() );

instead of removing body , creating again in new position


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