Why does alertDialog cause my app to crash?

Question

public class SignUpActivity extends AppCompatActivity {

private CircleImageView profilePic,galleryPick,cameraPick;
private ActivityResultLauncher<Intent> activityResultLauncher;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_sign_up);

    profilePic = findViewById(R.id.circular_image);

    
    activityResultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), new ActivityResultCallback<ActivityResult>() {
        @Override
        public void onActivityResult(ActivityResult result)
        {
            if(result.getResultCode() == RESULT_OK && result.getData() != null)
            {
                Bundle bundle = result.getData().getExtras();
                Bitmap bitmap = (Bitmap) bundle.get("data");
                profilePic.setImageBitmap(bitmap);
            }
        }
    });

    profilePic.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v)
        {
           chooseProfilePic();
        }
    });

}


private void chooseProfilePic()
{
    AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
    LayoutInflater inflater = getLayoutInflater();
    View dialogView = inflater.inflate(R.layout.alert_dialog,null);
    builder.setCancelable(false);
    builder.setView(dialogView);

    galleryPick = findViewById(R.id.gallery_pick);
    cameraPick = findViewById(R.id.camera_pick);

    AlertDialog alertDialog = builder.create();
    alertDialog.show();



    cameraPick.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v)
        {
            Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            if(cameraIntent.resolveActivity(getPackageManager()) != null)
            {
                activityResultLauncher.launch(cameraIntent);
            }
        }
    });
}

}

So I am a beginner in Android Studio and since startForActivityResult is deprecated I am looking for something to replace it. The new method works but there occurs a problem when used with private method including the alert dialog.

Answer 1

You are finding the resourceId of the button in the dialog from wrong view. Buttons are present in dialog while you are finding it from activity/fragment view.
Update your code to find it from dialogView.

 AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
    LayoutInflater inflater = getLayoutInflater();
    View dialogView = inflater.inflate(R.layout.alert_dialog,null);
    builder.setCancelable(false);
    builder.setView(dialogView);

    galleryPick = dialogView.findViewById(R.id.gallery_pick); // find id from dialog view
    cameraPick = dialogView.findViewById(R.id.camera_pick); // find id from dialog view

    AlertDialog alertDialog = builder.create();
    alertDialog.show();