How to check, in which contentView am I actually? Android Studio

Question

Hi!

I have some issues with my Android App, i'm working in only one class (I know it's so bad, but for now its the fastest options for me), I have base activity layout (activity_main.xml), i have 2 buttons on this layout, one of these button have setOnClickListener to open file manager to pick photo and add it on photo.xml.

imageBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.INTERNAL_CONTENT_URI);
                startActivityForResult(i, ACTIVITY_SELECT_IMAGE);

            }
        });

protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        super.onActivityResult(requestCode, resultCode, data);
        switch(requestCode) {
            case 1234:
                if(resultCode == RESULT_OK){
                    Uri selectedImage = data.getData();
                    String[] filePathColumn = {MediaStore.Images.Media.DATA};

                    Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);
                    cursor.moveToFirst();

                    int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
                    String filePath = cursor.getString(columnIndex);
                    cursor.close();


                    Bitmap SelectedImage = BitmapFactory.decodeFile(filePath);
                    setContentView(R.layout.photo);
                    ImageView img = findViewById(R.id.image);



                    int screenWidth = DeviceDimensionsHelper.getDisplayWidth(this);
                    int screenHeight = DeviceDimensionsHelper.getDisplayHeight(this);

                    Bitmap SelectedImageScaled = Bitmap.createScaledBitmap(SelectedImage, screenWidth, screenHeight, true);
                    img.setImageBitmap(SelectedImageScaled);

                }
            }
        }

And, then I have OnTouchEvent where I'm searching for ConstraintLayout which have id=photo, and it's in photo.xml, BUT if I'm in the main_activity.xml and then if I click somewhere other than button, aplication will crash, bcs it finding for a ConstraintLayout in photo.xml but aplication is still in main_acitivity.xml.

    public boolean onTouchEvent(MotionEvent event) {
        
            switch (event.getAction()) {

                case MotionEvent.ACTION_UP:
                    int x = (int)event.getX();
                    int y = (int)event.getY();
                    TextView tv;
                    if(i < 2) {
                        tv = new TextView(MainActivity.this);
                        tv.setText("\u29bf");
                        tv.setId(tv.generateViewId());
                        ConstraintLayout constraintLayout = (ConstraintLayout)findViewById(R.id.photo);
                        constraintLayout.addView(tv);
                        tv.setX(x);
                        tv.setY(y-360);


                        if(i == 0){
                            pos[0] = constraintLayout.findViewById(tv.getId()).getX();
                            pos[1] = constraintLayout.findViewById(tv.getId()).getY();
                        } else {
                            pos[2] = constraintLayout.findViewById(tv.getId()).getX();
                            pos[3] = constraintLayout.findViewById(tv.getId()).getY();
                            Log.i("222", "x1= " + pos[0] + " y1= " + pos[1] + " x2= " + pos[2] + " y2= " + pos[3]);
                            if(pos[2] < pos[0] && pos[1] < pos[3]){
                                Toast.makeText(getBaseContext(), "Różnica X= " + String.valueOf((int)(pos[0] - pos[2])) + " , różnica Y= " + String.valueOf((int)(pos[3] - pos[1])), Toast.LENGTH_SHORT).show();
                            }
                            else if(pos[2] < pos[0] && pos[1] > pos[3]){
                                Toast.makeText(getBaseContext(), "Różnica X= " + String.valueOf((int)(pos[0] - pos[2])) + " , różnica Y= " + String.valueOf((int)(pos[1] - pos[3])), Toast.LENGTH_SHORT).show();
                            }
                            else if(pos[2] > pos[0] && pos[1] < pos[3]){
                                Toast.makeText(getBaseContext(), "Różnica X= " + String.valueOf((int)(pos[2] - pos[0])) + " , różnica Y= " + String.valueOf((int)(pos[3] - pos[1])), Toast.LENGTH_SHORT).show();
                            }
                            else if(pos[2] > pos[0] && pos[1] > pos[3]){
                                Toast.makeText(getBaseContext(), "Różnica X= " + String.valueOf((int)(pos[2] - pos[0])) + " , różnica Y= " + String.valueOf((int)(pos[1] - pos[3])), Toast.LENGTH_SHORT).show();
                            }
                        }

                        i++;
                    }

            }
            
        return false;
    }

How Can i create if in onTouchEvent that will check if am I in the photo.xml and not in other?

Answer 1

You really should have separate Activities (or Fragments) for each piece of functionality and instead of replacing the current view, start the new Activity (or Fragment) when you get your image. That will be best in the long run so I'd suggest that.

That said - to fix this now - you can just do a null check in onTouchEvent:

ConstraintLayout constraintLayout = findViewById(R.id.photo);
if (constraintLayout == null) {
    return false;
}