Question

I have class A, with methods foo and bar, that are implemented by A1 and A2. The functionality in both A1 and A2 is the same. In other words:

   public class A {
       public int foo() { return 0; };
       public int bar() { return 1; };
   }

    class A1 extends A {      
        public int AnotherFooFunction() { return foo(); }
        public int AnotherBarFunction() { return bar(); }
    }

    class A2 extends A { 
        public int AnotherFooFunction() { return foo(); }
        public int AnotherBarFunction() { return bar(); }
    }

Is it better to keep the code in this fashion, or to swap out those virtual methods as static methods? (In Java, everything non-final/non-private is considered virtual, right?)

According to the Designing for Performance section in the Android Developer Docs, I should swap out these virtual methods for static ones. So the above becomes:

   public class A {
        public int foo() { return 0; };
        public int bar() { return 1; };
   }

    class A1 extends A {      
        public int AnotherFooFunction() { return A.foo(); }
        public int AnotherBarFunction() { return A.bar(); }
    }

    class A2 extends A { 
        public int AnotherFooFunction() { return A.foo(); }
        public int AnotherBarFunction() { return A.bar(); }
    }

Is this how it “ought” to be? I fully realize that I may be misinterpreting this paragraph in the docs.

Answer 1

There is no point in making wrappers for methods in base class, because they will be present in the derived class anyway.

Regarding to the performance tip from Android’s website – what they meant is to make a method static, if you find out that it’s body doesn’t refer to any non-static field or method. This will remove the overhead to passing a this pointer internally.

Anyway, to bother tuning down your application for performance at such fine-grained level, you must have a proof (by profiling) that exactly this method is causing a slow down. Optimizing random portions of the code, even if it’s based on a guess, is a waste of time.