Consider just using composition instead of trying to simulate Multiple Inheritance. You can use Interfaces to define what classes make up the composition, eg: ISteerable implies a property of type SteeringWheel, IBrakable implies a property of type BrakePedal, etc. Once you’ve done that, you could use the Extension Methods feature added to C# 3.0 to … Read more
Edit: as of Java 8, lambda expressions are a nice solution as other answers have pointed out. The answer below was written for Java 7 and earlier… Take a look at the command pattern. // NOTE: code not tested, but I believe this is valid java… public class CommandExample { public interface Command { public … Read more
Almost always List is preferred over ArrayList because, for instance, List can be translated into a LinkedList without affecting the rest of the codebase. If one used ArrayList instead of List, it’s hard to change the ArrayList implementation into a LinkedList one because ArrayList specific methods have been used in the codebase that would also … Read more
Implicit is when you define your interface via a member on your class. Explicit is when you define methods within your class on the interface. I know that sounds confusing but here is what I mean: IList.CopyTo would be implicitly implemented as: public void CopyTo(Array array, int index) { throw new NotImplementedException(); } and explicitly … Read more
Interface vs Base class
Interface vs Abstract Class (general OO)
Interfaces are used as a contract for classes that inherit it. This means any public methods/properties you want the interface to expose, must also be exposed in the inherited class. In the case above, you don’t have any public methods/properties exposed in the interface. Let me show you an example. Interface ITest { void AddPerson(string … Read more
The signature of the method defines which one will be invoked. The signature of your 2 show methods are different. The first does not take any argument, the second takes an int argument. As the argument is to be provided when invoking the method, the method to invoke has been defined.
Create your List reference with initialization as follows List list = new ArrayList(); if you want to update existing use the following list.clear(); list.addAll(newList); Thats it. if not fixed post your code first.
A few points to consider: Interfaces didn’t have default methods until Java 8. That a in your interface is implicitly final. Interfaces can’t define public mutable fields. Interfaces can’t define private (or protected, or package) fields. Interfaces can’t have protected or package methods; they couldn’t have private methods until Java 9. Abstract classes don’t have … Read more