Undetected Null Pointer Exception - android-studio

Question

I have an error regarding Null Pointer Exception and I can't find the exact location of the error in my program. I have searched for probable solutions online but I find none of them helpful. I know what Null Pointer Exception is but I can't pinpoint what went wrong in my code. Any help will be appreciated, thanks.
Here's my code:
LevelOneScreen.java
public class LevelOneScreen implements Screen {
private final ThumbChase app;
WalkAnimate walkAnimate;
private Stage stage;
private Image levelOneImage;
private Image holdStartImage;
public Image walkRightImage;
public Image walkLeftImage;
public float deltaTime = Gdx.graphics.getDeltaTime();
public LevelOneScreen(final ThumbChase app){
this.app = app;
this.stage = new Stage(new StretchViewport(app.screenWidth,app.screenHeight , app.camera));
}
#Override
public void show() {
Gdx.input.setInputProcessor(stage);
walkAnimate = new WalkAnimate();
levelOneBackground();
holdStart();
ninjaWalk(); ==>ERROR1:LevelOneScreen.java:54
}
public void holdStart(){
Texture holdStartTexture = new Texture("HoldStart.png");
holdStartImage = new Image(holdStartTexture);
float holdStartImageW = holdStartImage.getWidth();
float holdStartImageH = holdStartImage.getHeight();
float holdStartImgWidth = app.screenWidth*0.8f;
float holdStartImgHeight = holdStartImgWidth *(holdStartImageH/holdStartImageW);
holdStartImage.isTouchable();
holdStartImage.setSize(holdStartImgWidth,holdStartImgHeight);
holdStartImage.setPosition(stage.getWidth()/2-holdStartImgWidth/2,stage.getHeight()/2-holdStartImgHeight/2);
stage.addActor(holdStartImage);
holdStartImage.addListener(new ActorGestureListener(){
public void touchDown (InputEvent event, float x, float y, int pointer, int button){
holdStartImage.setVisible(false);
};
});
}
public void levelOneBackground(){
Texture levelOneTexture = new Texture("BGBlue Resize.png");
levelOneImage = new Image(levelOneTexture);
levelOneImage.setSize(app.screenWidth,app.screenHeight);
levelOneImage.setPosition(0,0);
stage.addActor(levelOneImage);
levelOneImage.addListener(new ActorGestureListener(){
public void touchDown (InputEvent event, float x, float y, int pointer, int button){
holdStartImage.setVisible(false);
};
});
}
public void ninjaWalk(){
ERROR2==> TextureRegion ninjaWalkRight = new TextureRegion(walkAnimate.getCurrentFrameRight());
TextureRegion ninjaWalkLeft = new TextureRegion(walkAnimate.getCurrentFrameLeft());
walkRightImage = new Image(ninjaWalkRight);
walkLeftImage = new Image(ninjaWalkLeft);
float walkImageW = walkRightImage.getWidth();
float walkImageH = walkRightImage.getHeight();
float walkImageWidth = app.screenWidth*0.15f;
float walkImageHeight = walkImageWidth*(walkImageH/walkImageW);
walkLeftImage.isTouchable();
walkRightImage.isTouchable();
walkRightImage.setSize(walkImageWidth,walkImageHeight);
walkLeftImage.setSize(walkImageWidth,walkImageHeight);
walkRightImage.setPosition(stage.getWidth()/2-walkImageWidth/2,0);
walkLeftImage.setPosition(stage.getWidth()/2-walkImageWidth/2,0);
walkLeftImage.addAction(moveBy(3f,3f,3f));
stage.addActor(walkLeftImage);
}
#Override
public void render(float delta) {
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
walkAnimate.update(deltaTime);
update(delta);
}
public void update(float delta){
stage.act(delta);
stage.draw();
app.batch.begin();
app.batch.end();
}
#Override
public void resize(int width, int height) {
}
#Override
public void pause() {
}
#Override
public void resume() {
}
#Override
public void hide() {
}
#Override
public void dispose() {
stage.dispose();
}
}
WalkAnimate.java
public class WalkAnimate {
public ThumbChase app;
public Stage stage;
private Animation walkAnimationRight;
private Animation walkAnimationLeft;
private Texture walkSheetRight;
private Texture walkSheetLeft;
private TextureRegion[] walkFramesRight;
private TextureRegion[] walkFramesLeft;
private TextureRegion currentFrameRight;
private TextureRegion currentFrameLeft;
private float stateTime;
private Rectangle bound; //used for positioning and collision detection
private static final int FRAME_COLS_WALK = 3;
private static final int FRAME_ROWS_WALK= 2;
private float screenWidth = Gdx.graphics.getWidth();
private float screenHeight = Gdx.graphics.getHeight();
public float currentFrameWidth = (float)(screenHeight*0.15);
public float currentFrameHeight = (float)(screenHeight*0.15);
public float walkSheetWidth;
public float walkSheetHeight;
public WalkAnimate () {
walkSheetRight = new Texture("ninjaWalkRight.png");
walkSheetWidth = walkSheetRight.getWidth();
walkSheetHeight = walkSheetRight.getWidth();
TextureRegion[][] tmp = TextureRegion.split(walkSheetRight, (int) walkSheetRight.getWidth() / FRAME_COLS_WALK, (int) walkSheetRight.getHeight() / FRAME_ROWS_WALK);
walkFramesRight = new TextureRegion[FRAME_COLS_WALK * FRAME_ROWS_WALK];
int index = 0 ;
for (int i = 0; i < FRAME_ROWS_WALK; i++) {
for (int j = 0; j < FRAME_COLS_WALK; j++) {
walkFramesRight[index++] = tmp[i][j];
}
}
walkAnimationRight = new Animation(0.044f, walkFramesRight);
stateTime = 0f;
walkSheetLeft = new Texture("ninjaWalkLeft.png");
walkSheetWidth = walkSheetLeft.getWidth();
walkSheetHeight = walkSheetLeft.getWidth();
TextureRegion[][] tmp1 = TextureRegion.split(walkSheetLeft, (int) walkSheetRight.getWidth() / FRAME_COLS_WALK, (int)walkSheetLeft.getHeight() / FRAME_ROWS_WALK);
walkFramesLeft = new TextureRegion[FRAME_COLS_WALK * FRAME_ROWS_WALK];
int index1 = 0;
for (int i = 0; i < FRAME_ROWS_WALK; i++) {
for (int j = 0; j < FRAME_COLS_WALK; j++) {
walkFramesLeft[index1++] = tmp1 [i][j];
}
}
walkAnimationLeft = new Animation(0.044f, walkFramesLeft);
stateTime = 0f;
}
public Rectangle getBound(){
return bound;
}
public void update(float delta){
stateTime += delta;
currentFrameRight = walkAnimationRight.getKeyFrame(stateTime, true);
currentFrameLeft = walkAnimationLeft.getKeyFrame(stateTime, true);
}
public TextureRegion getCurrentFrameRight(){
return currentFrameRight;
}
public TextureRegion getCurrentFrameLeft(){
return currentFrameLeft;
}
}
And here's the error:
> java.lang.NullPointerException
> at
> com.badlogic.gdx.graphics.g2d.TextureRegion.setRegion(TextureRegion.java:112)
> at
> com.badlogic.gdx.graphics.g2d.TextureRegion.<init>(TextureRegion.java:63)
> at
> com.jpfalmazan.thumbchaseninja.GameScreens.LevelOneScreen.show(LevelOneScreen.java:54)
> at com.badlogic.gdx.Game.setScreen(Game.java:61)
> at
> com.jpfalmazan.thumbchaseninja.GameScreens.MenuScreen$1.clicked(MenuScreen.java:82)
> at
> com.badlogic.gdx.scenes.scene2d.utils.ClickListener.touchUp(ClickListener.java:89)
> at
> com.badlogic.gdx.scenes.scene2d.InputListener.handle(InputListener.java:58)
> at com.badlogic.gdx.scenes.scene2d.Stage.touchUp(Stage.java:353)
> at
> com.badlogic.gdx.backends.android.AndroidInput.processEvents(AndroidInput.java:379)
> at
> com.badlogic.gdx.backends.android.AndroidGraphics.onDrawFrame(AndroidGraphics.java:457)
> at
> android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1516)
> at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1240)

Answer 1

you can find the exact line in logcat logs, you can see the activity name as well as the line of code and by clicking on it you will be redirected to the individual Activity on same line..
Hope this will help you.

Answer 2

One of your textures is either named wrong, or you are attempting to access it before it has been loaded.
You can tell by this exception;
com.badlogic.gdx.graphics.g2d.TextureRegion.setRegion(TextureRegion.java:112)
This mean that the texture region cannot map the texture identifier to a valid texture in your program, so either ninjaWalkRight or ninjaWalkLeft does not exist or is not loaded.
If you are using texture packer then ensure your files are called ninjaWalkRight and ninjaWalkLeft.
Also use the AssetManager to ensure these files are loaded before trying to access them as that may be an issue also.

Answer 3

Looks like you don't call walkAnimate.update(dt) before calling walkAnimate.getCurrentFrameRight() the first time, so walkAnimate.getCurrentFrameRight() returns null.
Moreover, in ninjaWalk() you create two actors (walkRightImage and walkLeftImage), only add one to the stage and never update the texture of it. You should rework your concept: Create one actor at startup, store it in a field and change the texture of it in your render/update method.