Android Intents, questions about setClass()

Question

I just started learning android programming and while working through the android Tab Layout tutorial I noticed they created a new Intent with the following code.

// Create an Intent to launch an Activity for the tab (to be reused)
intent = new Intent().setClass(this, ArtistsActivity.class);

Up until now, all the books I've read have created a new intent using

intent = new Intent(this, ArtistActivity.class);

and was wondering if there is a difference between the two lines of code.

Answer 1

They are equivalent.

Based on the comment from the tutorial...

// Create an Intent to launch an Activity for the tab (to be reused)

It seems they just use the .setClass() method instead of the Constructor that takes a class to be more explicit as the Intent item created there will be reused and .setClass() will probably be called on it again.

Answer 2

You can use .setClass when the same Intent may have two different class depending on some condition. Here's an exemple :

 Intent resultIntent = new Intent();

  if (condition) {
     resultIntent.setClass(getApplicationContext(), XXXX.class);
                startActivity(resultIntent);
  }else {
     resultIntent.setClass(getApplicationContext(), YYYY.class);
  }

Answer 3

There's no practical difference. There is just a difference on how it's being done. One is using the constructor, while the other one a setter. But the end result is exactly the same. See the documentation.