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Suppose you want to start a new activity and pass it some data from the current activity. If the data is of a primitive type you could simply use an intent and add extras, but how would you do this for more complex data structures like arraylists or objects?
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You have a few options: You could wrap the more complex structure in a class that implements the Parcelable interface, which can be stored in an extra. You could wrap the more complex structure in a class that implements the Serializable interface, which can be stored in an extra.
We can send the data using putExtra() method from one activity and get the data from the second activity using the getStringExtra() method.
Non-primitive types are created by the programmer and is not defined by Java (except for String ). Non-primitive types can be used to call methods to perform certain operations, while primitive types cannot. A primitive type has always a value, while non-primitive types can be null .
When you pass a primitive, you actually pass a copy of value of that variable. This means changes done in the called method will not reflect in original variable. When you pass an object you don't pass a copy, you pass a copy of 'handle' of that object by which you can access it and can change it.
You have a few options:
Parcelable interface, which can be stored in an extraSerializable interface, which can be stored in an extraSharedPreferences)Application or a local Service What you do not want to do is pass big stuff via extras. For example, if you are creating an application that grabs pictures off the camera, you do not want to pass those in extras -- use a static data member (icky as that sounds). Intents are designed to work cross-process, which means there is some amount of data copying that goes on, which you want to avoid when it is not necessary for big stuff.
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