extends

Can an interface extend multiple interfaces in Java? This code appears valid in my IDE and it does compile: interface Foo extends Runnable, Set, Comparator<String> { } but I had heard that multiple inheritance was not allowed in Java. Why does there appear to be an exception for interfaces? Suresh Atta Yes, you can do it. An interface can extend multiple interfaces, as shown here: interface Maininterface extends inter1, inter2, inter3 { // methods } A single class can also implement multiple interfaces. What if two interfaces have a method defining the same name and signature? There is a

I am just trying to understand the extends keyword in Java Generics. List<? extends Animal> means we can stuff any object in the List which IS A Animal then won't the following also mean the same thing: List<Animal> Can someone help me know the difference between the above two? To me extends just sound redundant here. Thanks! List<Dog> is a subtype of List<? extends Animal> , but not a subtype of List<Animal> . Why is List<Dog> not a subtype of List<Animal> ? Consider the following example: void mySub(List<Animal> myList) { myList.add(new Cat()); } If you were allowed to pass a List<Dog> to

I need to create a base class that extends Activity which does some common tasks in my application and extend my activities from it,in the following form: public BaseActivity extends Activity{....} public SubActivity extends BaseActivity{...} in SubActivity I need to give values to some variables and UI components defined in BaseActivity , I may need to define a different layout for SubActivity according to some flag value, also(in SubActivity ) I want to execute asyncTask that is defined in BaseActivity . is this possible? if yes, is there any tutorial that may help? thank you in advance What

I am currently transforming from Java to Javascript, and it's a bit hard for me to figure out how to extend objects the way I want it to do. I've seen several people on the internet use a method called extend on object. The code will look like this: var Person = { name : 'Blank', age : 22 } var Robot = Person.extend({ name : 'Robo', age : 4 )} var robot = new Robot(); alert(robot.name); //Should return 'Robo' Does anyone know how to make this work? I've heard that you need to write Object.prototype.extend = function(...); But I don't know how to make this system work. If it is not possible,

If I have several classes with functions that I need but want to store separately for organisation, can I extend a class to have both? i.e. class a extends b extends c edit: I know how to extend classes one at a time, but I'm looking for a method to instantly extend a class using multiple base classes - AFAIK you can't do this in PHP but there should be ways around it without resorting to class c extends b , class b extends a Answering your edit : If you really want to fake multiple inheritance, you can use the magic function __call(). This is ugly though it works from class A user's point of