How to change activity without input data?

Question

I am trying to use intent to pass input data to another activity. it works well by the way, but when I try to change the activity without any input data, application shuts down. How can I change the activity without input data and image file?

Here is the upload activity code :

imageView = (ImageView) findViewById(R.id.imageview);
    Button uploading = (Button) findViewById(R.id.upload_upload);
    uploading.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            Bitmap bitmap = ((BitmapDrawable)imageView.getDrawable()).getBitmap();
            float scale = (float) (1024/(float)bitmap.getWidth());
            int image_w = (int) (bitmap.getWidth() * scale);
            int image_h = (int) (bitmap.getHeight() * scale);
            Bitmap resize = Bitmap.createScaledBitmap(bitmap, image_w, image_h, true);
            resize.compress(Bitmap.CompressFormat.JPEG, 100, stream);
            byte[] byteArray = stream.toByteArray();

            Intent intent = new Intent(upload.this,MainActivity.class);

            intent.putExtra("integer", 300);
            intent.putExtra("double", 3.141592);
            intent.putExtra("image", byteArray);


            EditText input_title = (EditText) findViewById(R.id.upload_title);
            String temp1 = input_title.getText().toString();
            intent.putExtra("temp1",temp1);

            EditText input_author = (EditText) findViewById(R.id.upload_author);
            String temp2 = input_author.getText().toString();
            intent.putExtra("temp2",temp2);
            
            startActivity(intent);
        }
    });

MainActivity code :

ImageView imageView = (ImageView) findViewById(R.id.main_image);

    Bundle extras = getIntent().getExtras();
    byte[] byteArray = getIntent().getByteArrayExtra("image");
    Bitmap bitmap = BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);

    imageView.setImageBitmap(bitmap);

    text_title = (TextView) findViewById(R.id.title); 

    Intent receiver = getIntent();

    String title_temp = receiver.getStringExtra("temp1");
    text_title.setText(title_temp);

    text_author = (TextView)  findViewById(R.id.author);

    String author_temp = receiver.getStringExtra("temp2");
    text_author.setText(author_temp);

gioravered · Answer

You didn't add any crash log, but by looking at your code I see you don't verify the Intent extras is not null. This may lead to a NullPointerException and could definitely be the reason for the crash.

Add a null check before using the Intent:

Bundle extras = getIntent().getExtra();
if (extras != null) {
    ImageView imageView = (ImageView) findViewById(R.id.main_image);

    byte[] byteArray = receiver.getByteArrayExtra("image");
    Bitmap bitmap = BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);

    imageView.setImageBitmap(bitmap);

    text_title = (TextView) findViewById(R.id.title); 


    String title_temp = receiver.getStringExtra("temp1");
    text_title.setText(title_temp);

    text_author = (TextView)  findViewById(R.id.author);

    String author_temp = receiver.getStringExtra("temp2");
    text_author.setText(author_temp);
}

Huma · Answer

You'll have to check if your intent have extras or not by the following check otherwise it'll throw NullpointerExxception. it will only set values if intent have extras

   if (receiver.getExtras() != null){
    
    String title_temp = receiver.getStringExtra("temp1");
    text_title.setText(title_temp);

    text_author = (TextView)  findViewById(R.id.author);

    String author_temp = receiver.getStringExtra("temp2");
    text_author.setText(author_temp);
}

or you can also check specific extras by this

    if (receiver.getExtras() != null && receiver.getExtras().containsKey("temp1")) {
        String title_temp = receiver.getStringExtra("temp1");
        text_title.setText(title_temp);
    }

How to change activity without input data?

2 Answers