Private interface methods are only supported starting with Android N (--min-api 24) code example

Example 1: javascript check if is array

var colors=["red","green","blue"];

if(Array.isArray(colors)){
    //colors is an array
}

Example 2: doest all the methos in interface need to implement c#

You have two choices:

- implement every method required by the interface
or
- declare the missing methods abstract in your class. This forces you
to declare your class abstract and, as a result, forces you to
subclass the class (and implement the missing methods) before you
can create any objects.