What is the meaning of android.intent.action.MAIN?

android.intent.action.MAIN means that this activity is the entry point of the application, i.e. when you launch the application, this activity is created. From the docs Also,from here Activity Action Start as a main entry point, does not expect to receive data. android.intent.category.DEFAULT is mainly used for implicit intents. If your activity wishes to be started by an implicit intent … Read more

How to pass an object from one activity to another on Android

One option could be letting your custom class implement the Serializable interface and then you can pass object instances in the intent extra using the putExtra(Serializable..) variant of the Intent#putExtra() method. Pseudocode: Note: Make sure each nested class of your main custom class has implemented Serializable interface to avoid any serialization exceptions. For example:

Android : When do we use getIntent()?

http://developer.android.com/reference/android/app/Activity.html#getIntent() Return the intent that started this activity. If you start an Activity with some data, for example by doing you can retrieve this data using getIntent in the new activity: So, it’s not for handling returning data from an Activity, like onActivityResult, but it’s for passing data to a new Activity.