Handling back button press Inside Fragments

This is the fourth part of a 6 posts series on Fragment oriented application architecture. In the previous post I talked about Inter-Fragment Communication. In this part I am going discuss about elegantly handling back button press inside fragments in a fragment oriented application.

(Sample application's source code and README)

Android devices have a hardware back button which normally serves the purpose of going back through the screens/actions stack. Callback to a back button press event is received in the foreground Activity (onBackPressed() event callback) which can be overridden and handled.

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Inter-Fragment Communication

This is the third part of a 6 posts series on Fragment oriented application architecture. In the previous post I talked about Transaction BackStack and its management. In this part I am going to talk about Inter-Fragment Communication. It's a general concept, not deeply linked to the context of this series.

(Sample application's source code and README)

It's a communication pattern over which fragments should talk to each other. Ideally, a fragment should never keep a reference of another fragment or even, in best case, of the specific parent activity. So, how would two fragments communicate? Consider the following scene.

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Transaction BackStack and its management

This is second part of a 6 posts series. In the first post I talked around basics of fragment oriented architecture. From this post onwards, I'll be talking about it's implementation details.

(Sample application's source code and README)

In this part I am going to talk about Transaction Backstack and few related methods that can be used frequently.
Transaction BackStack has often been misinterpreted as backstack of fragments. FragmentManager inside an activity deals with fragment-transactions rather than with fragments. An entry into this backstack is a 'fragment-transaction' which can be composed of one or more operations involving fragment(s). Reverting this would revert back all these operations together.

FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(restId, fragmentA);
ft.replace(fragmentB);
ft.commit();

Above, is a single transaction clubbing multiple operations.

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Advocating Fragment Oriented Applications in Android

This is a series of 6 blog posts which explains about Fragment Oriented Architecture in Android applications. In this first post, I'm going to explain what is Fragment Oriented Architecture and why shall one care. In subsequent posts I'm going to talk about following topics.

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Compiling native libraries for Android L

Preparing your app for Android L ?

While using native executables in our existing Android apps we observed that those executables were no more working with Android L. We came to know that Android has introduced one more security feature starting from Android L i.e
Executable must be PIE (Position independent executable).

To compile a library adhering to above security feature you just need to follow these steps:

  1. Set following LDFLAGS or linker flags : -pie -fPIE
  2. Add --with-pic option while configuring the library.

Some libraries might use different configure options to compile the code with PIC (Position Independent Code) so to check all available configure options for PIC you can use this command:

./configure -h | grep -i pic

If there is no PIC option in configure script then you can try passing -fPIC option with your CFLAGS.

Now, compile the project (make, make install) and it should generate PIE.

To check if you've successfully generated a Position Independent Executable (PIE)

You can use "hardening-includes" package on Ubuntu or Debian.

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