Question

Here is my first activity code from where I call the second Activity:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
  if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT){       
    startActivityForResult(new Intent("chap.two.Chapter2Activity2"),request_Code);          
  }    
  return false;
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
  if (requestCode == request_Code) {
    if (resultCode == RESULT_OK) 
      Toast.makeText(this,data.getData().toString(),Toast.LENGTH_SHORT).show();             
  }
}

And here is a code of chap.two.Chapter2Activity2:

Button n = (Button) findViewById(R.id.btn_OK);
n.setOnClickListener(new View.OnClickListener() {               
   @Override
   public void onClick(View v) {
     // TODO Auto-generated method stub

     Intent data = new Intent();
     //---get the EditText view---
     EditText txt_username =(EditText) findViewById(R.id.txt_username);
     //---set the data to pass back---
     data.setData(Uri.parse(txt_username.getText().toString()));
     setResult(RESULT_OK, data);
     //---closes the activity---
     finish();

   }
});

here I see that setResult(RESULT_OK, data) has two arguments but
onActivityResult(int requestCode, int resultCode, Intent data) has three and I want know how onActivityResult gets value for third parameter? How it works can anyone tell me? Why isn’t this error ?

Answer 1

When you call Activity.startActivityForResult(), you set the requestCode. Later, this request code is needed by onActivityResult() in order to determine what Activity is sending data to it. We don’t need to supply requestCode again on setResult() because the requestCode is carried along.

The data is intent data returned from launched intent. We usually use this data when we set extras on the called intent.

Consider this example:

CALL SECOND ACTIVITY

Intent i = new Intent(MainActivity.this, CheckActivity.class);
startActivityForResult(i, REQUEST_CODE_CHECK);

ON SECOND ACTIVITY, SET INTENT RESULT

getIntent().putExtra("TADA", "bla bla bla");
setResult(RESULT_OK, getIntent());
finish();

BACK TO FIRST ACTIVITY, ONACTIVITYRESULT()

if(requestCode == REQUEST_CODE_CHECK && resultCode == RESULT_OK){
    text1.setText(data.getExtras().getString("TADA") );
}

There you go. You should now understand what is Intent data and how to set and fetch the value.