LazyInit.kt

class SomeActivity : Activity() {
    val f: Foo by lazy { createFoo() } // put your initialization block here
  
    fun onCreate(bundle: Bundle?) {
        f.foo() // f will be created here and it's a val so you can't change it
        f // or you can call a getter just to initialize it
    }
    
    fun createFoo() = Foo(this)
    // this is useful when you need a context after the activity is created

}