How (this::methodName) is working in this code?

Question

In this question there is one line,

findViewById(R.id.go_to_play_store).setOnClickListener(this::goToPlayStore);

how does this line is exactly handling the click listener ?

Answer 1

Java8 introduces concept of Method references and Functional interfaces. If function onClickListener requires a function with one argument(a.k.a Functional Interface) then if return types and argument types match your function(which is goToPlayStore) then you can pass its reference as functional interface.

Answer 2

This is the new JAVA 8 language feature Lambda Expressions.

:: refer to a new syntax in Java 8 known as method references. You can reference a class or instance and pass along the method that will handle the event

On click its calling function called goToPlayStore () located in that activity or fragment.