How to replace anonymous class using lambda expression android

Question

We used lots of anonymous class in android project. For example:

new DialogInterface.OnClickListener()

new MediaPlayer.OnPreparedListener()

etc. Is there any way to replace these kinds of anonymous class using new Java lambda expression?

Answer 1

You can only replace anon classes for functional interfaces. Lambda expression requires a functional interface i.e. interface that contains only single method.

You have to

1. enable jack in your app's gradle:

   'defaultConfig { ... jackOptions { enabled true } } compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 targetCompatibility JavaVersion.VERSION_1_8 } }'

2. now you can replace your anonymous class with lambda expression. for example: replace

   mView.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {
           onSomethingClicked();
       }
   });
   

to

 mView.setOnClickListener(view -> onSomethingClicked())

It is important to keep in mind that enabling jack still generates anonymous classes during the compile step. So, be careful about all the leaks you can have with anonymous classes.