CODEWITHSUNDEEP
javaandroidandroid-intentandroid-activity
dylan7
dylan7

Reputation: 813

Intra/Inter-activity communication

I am mostly a beginner to android development, and I find myself using a lot of global variables to share data between functions within the same activity, Intra-activity communication . This is mostly because no one calls onCreate () from within the activity, so I can't return UI elements and data that might be edited latter in the activity.

In addition for inter-activity communication I find myself using Intent extras for small data and external classes with static variables to pass large data, image strings, around when an activity dies. I read here that the application context can also be used to maintain global variables,so this might be a solution, however this keeps the variable for Intra-activity communication alive even after it dies, which is unnecessary. In addition some of that data passed may not be needed all the time for all the activities.

That seems like poor practice, so my questions :

1)For inter-activity communication is a constant use of intent extras and static variables to pass data ok?

2) For Intra-activity communication what can I use instead of global variables to pass data between different functions that don't call each other but share some value and the value dies with the activity ? Is there a danger to such use of global variables ?

If this is too opinionated or abstract I'll close it.

Upvotes: 0

Views: 265

Answers (1)

aelimill
aelimill

Reputation: 1015

1) Usage of intent is ok. As for global variables I do not think so. The values can be lost when your application would be recreated after android system decides to free some memory. Why not persist data in SharedPreferences or SQLite?

2) Fields (and classes) variable is a normal way to use (and pretty good practice for the cases like not using findViewById all the time). If you want to persist data between activity recreation why not to use provided by android framework (https://developer.android.com/training/basics/activity-lifecycle/recreating.html)?

Save the needed data (like item ids, values, etc) in bundle and restore them afterwards.

public void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstance.putInt(some_key,value);
}

and restore in onCreate or onRestoreInstanceState.

Upvotes: 1

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