Runtime Error, by starting the Application

Question

I have written a small app in Android Studio. If I start the app in the emulator, then I get an exception. The application simply stops.

The source code looks as follows:

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private int points, round, countdown;
    private static final int FROG_ID = 212121;
    private Random rnd = new Random();
    private Handler handler = new Handler();


    private Runnable runnable = new Runnable(){
        @Override
        public void run(){
            countdown();
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //newGame();
        showStartFragment();
    }


    private void newGame(){
        points = 0;
        round = 1;
        initRound();
    }

    private void initRound(){
        countdown = 10;
        ViewGroup container = (ViewGroup) findViewById(R.id.container);
        container.removeAllViews();
        WimmelView wv = new WimmelView(this);
        container.addView(wv, ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT);
        wv.setImageCount(5*(10+round));
        ImageView frog = new ImageView(this);
        frog.setId(FROG_ID);
        frog.setImageResource(R.drawable.frog1);
        frog.setScaleType(ImageView.ScaleType.CENTER);
        float scale = getResources().getDisplayMetrics().density;
        FrameLayout.LayoutParams lp= new FrameLayout.LayoutParams(Math.round(64*scale),Math.round(61*scale));
        lp.leftMargin = rnd.nextInt(container.getWidth()-64);
        lp.topMargin = rnd.nextInt(container.getHeight()-61);
        lp.gravity = Gravity.TOP + Gravity.START;
        frog.setOnClickListener(this);
        container.addView(frog, lp);
        handler.postDelayed(runnable, 1000-round*50);
        update();

    }

    private void fillTextView(int id, String text){
        TextView tv = (TextView) findViewById(id);
        tv.setText(text);
    }

    private void update(){
        fillTextView(R.id.points, Integer.toString(points));
        fillTextView(R.id.round, Integer.toString(round));
        fillTextView(R.id.countdown,
                Integer.toString(countdown*1000));
    }

    private void showStartFragment(){
        ViewGroup container = (ViewGroup) findViewById(R.id.container);
        container.removeAllViews();
        container.addView(
                getLayoutInflater().
                        inflate(R.layout.fragment_start, null));
        container.findViewById(R.id.start).setOnClickListener(this);
    }

    private void showGameOverFragment(){
        ViewGroup container = (ViewGroup) findViewById(R.id.container);
        container.addView(
                getLayoutInflater().
                        inflate(R.layout.fragment_gameover, null));
        container.findViewById(play_again).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        if(view.getId()==R.id.start){
            startGame();
        }else if(view.getId()==R.id.play_again){
            showStartFragment();
        }else if(view.getId()==FROG_ID){
            handler.removeCallbacks(runnable);
            Toast.makeText(this,R.string.kissed, Toast.LENGTH_SHORT).show();
            //showToast(R.string.kissed);
            points += countdown*1000;
            round++;
        }
        initRound();
    }


    private void startGame() {
        newGame();
    }

    private void countdown(){
        countdown--;
        update();
        if(countdown<=0){
            //frog.setOnClickListener(null);
            showGameOverFragment();
        }else {
            handler.postDelayed(runnable, 1000-round*50);
        }
    }

    @Override
    protected  void onPause(){
        super.onPause();
        handler.removeCallbacks(runnable);
    }
}

At the beginning I came so far that I could at least press on start, now I am not at all more in the application pure ... I have tried to googlen what it could be, but I have not succeeded in doing so. I also get a error message at the point frog.setId (FROG_ID).

In addition, I have yet another class, which implements images

public class WimmelView extends View {

    private Random rnd;
    private long randomSeed = 1;
    private int imageCount;
    private Paint paint = new Paint();


    private static  final int[]
            images = { R.drawable.frog2,
                      R.drawable.frog3,R.drawable.frog4,
                      R.drawable.frog5,R.drawable.frog6};

    public void setImageCount(int imageCount){
        this.imageCount = imageCount;
        randomSeed = System.currentTimeMillis();
        invalidate();
    }

    public WimmelView(Context context){
        super(context);
        paint.setAntiAlias(true);
    }

    @Override
    protected void onDraw(Canvas canvas){
        super.onDraw(canvas);
        rnd = new Random(randomSeed);
        for(int image:images){
            Bitmap bitmap =
                    BitmapFactory.decodeResource(getResources(),image);
            for(int i=0; i<imageCount/images.length; i++){
                float left = (float) (rnd.nextFloat()
                        *(getWidth()-bitmap.getWidth()));
                float top = (float) (rnd.nextFloat()
                        *(getWidth()-bitmap.getWidth()));
                canvas.drawBitmap(bitmap,left,top,paint);
            }
            bitmap.recycle();
        }
}
}

I hope someone sees the error and can help me ...

Answer 1

Your error is that the Content view is removing all children from the screen including the textviews of the score and points that you are trying to use. I just helped you move to fragments offline and ensured you were good to go. Goodluck.

Answer 2

You can use this,

<item name="frog_id" type="id"/>

This give you unique value. You add this in your ids.xml. and change your code

...
frog.setId(R.id.frog_id);
...
else if(view.getId()==R.id.frog_id)

Try this

Answer 3

This is related to setting the view id. You can't set the id with the following:

private static final int FROG_ID = 212121;

...
frog.setId(FROG_ID);

You need to define an id in res/values/ids.xml:

<?xml version="1.0" encoding="utf-8"?>

<resources>   
   <item name="your_view_id" type="id"/>     
</resources>

But this will against the purpose of creating a dynamic view.

Instead, you can use View.generateViewId for the id instead. But please remember that this method only work from API version 17. Here the excerpt:

int generateViewId ()

Generate a value suitable for use in setId(int). This value will not collide with ID values generated at build time by aapt for R.id.