Do you have to override interface methods?

Do you have to override interface methods?

The default methods are introduced in an interface since Java8. Unlike other abstract methods these are the methods can have a default implementation. If you have default method in an interface, it is not mandatory to override (provide body) it in the classes that are already implementing this interface.

Do you have to override all abstract methods?

An abstract method has no implementation. ... Subclasses of an abstract class must implement (override) all abstract methods of its abstract superclass. The non-abstract methods of the superclass are just inherited as they are. They can also be overridden, if needed.

What happens if we don't implement the methods of interface?

If you don't implement all methods of your interface, than you destroy the entire purpose of an interface. We can override all the interface methods in abstract parent class and in child class override those methods only which is required by that particular child class.

Is it mandatory to implement all the methods of an interface in ABAP?

A class must implement all methods of the interface in its implementation part, with the following exceptions: Interface methods declared as optional using the addition DEFAULT. Interface methods specified in the class after the addition ABSTRACT METHODS (making them abstract).

How do you override an interface?

If a base class already implements an interface and a derived class needs to implement the same interface but needs to override certain methods, you must reimplement the interface and set only the interface methods which need overriding.

Can we have method overloading in interface?

Yes, you can have overloaded methods (methods with the same name different parameters) in an interface. You can implement this interface and achieve method overloading through its methods.

Which method Cannot be overridden?

A method declared final cannot be overridden. A method declared static cannot be overridden but can be re-declared. If a method cannot be inherited, then it cannot be overridden. A subclass within the same package as the instance's superclass can override any superclass method that is not declared private or final.

Can we override static method?

Static methods cannot be overridden because they are not dispatched on the object instance at runtime. The compiler decides which method gets called. Static methods can be overloaded (meaning that you can have the same method name for several methods as long as they have different parameter types).

Which one is used to implement the interface?

To implement interface use implements keyword. Why do we use interface ? It is used to achieve total abstraction. Since java does not support multiple inheritance in case of class, but by using interface it can achieve multiple inheritance .

Can we put a static method in interface?

Similar to Default Method in Interface, the static method in an interface can be defined in the interface, but cannot be overridden in Implementation Classes. To use a static method, Interface name should be instantiated with it, as it is a part of the Interface only.

Should we @ override an interface's method implementation?

• The Java doc cited by @Zhao is clearly referring to an abstract super class; an interface can not be called the supertype. So, @Override is redundant and not sensible for interface method implementations in concrete classes. For me, often times this is the only reason some code requires Java 6 to compile.

When to use the @ Override method in Java?

• If the class that is implementing the interface is an abstract class, @Override is useful to ensure that the implementation is for an interface method; without the @Override an abstract class would just compile fine even if the implementation method signature does not match the method declared in the interface;

How is an interface similar to a class in Java?

• Interface in Java is similar to class but, it contains only abstract methods and fields which are final and static. In a separate class you need to implement this interface and provide body for all its abstract methods.

When to use @ override in JDK 5?

• You should always annotate methods with @Override if it's available. In JDK 5 this means overriding methods of superclasses, in JDK 6, and 7 it means overriding methods of superclasses, and implementing methods of interfaces.