Sobrescrevendo o método onActivityResult

MainActivity.java

    @Override
	public void onActivityResult(int requestCode, int resultCode, Intent intent) {
		if (requestCode == 0 && resultCode == Activity.RESULT_OK) {
			String qrcode = intent.getStringExtra("SCAN_RESULT");
			
			TextView label = (TextView) findViewById(R.id.label);
			label.setText(qrcode);			
		} 
	}