While an abstract class can define both abstract and non-abstract methods, an interface can have only abstract methods. Another way interfaces differ from abstract classes is that interfaces have very little flexibility in how the methods and variables defined in the interface are declared. These rules are strict:
• All interface methods are implicitly public and abstract. In other words, you do not need to actually type the public or abstract modifiers in the method declaration, but the method is still always public and abstract. (You can use any kind of modifiers in the Abstract class)
• All variables defined in an interface must be public, static, and final-in other words, interfaces can declare only constants, not instance variables.
• Interface methods must not be static.
• Because interface methods are abstract, they cannot be marked final, strictfp, or native. (More on these modifiers later.)
• An interface can extend one or more other interfaces.
• An interface cannot extend anything but another interface.
• An interface cannot implement another interface or class.
• An interface must be declared with the keyword interface.
You must remember that all interface methods are public and abstract regardless of what you see in the interface definition.
An interface can only have abstract methods or constants in it. A class can have both that and everything else in Java.
All interfaces are abstract.
An interface in Java is like an abstract class, but there are no method bodies allowed in it and it has to be declared with the interface keyword. It is Java's way of getting around the Deadly Diamond of Death. Only abstract methods and constants are allowed in it.
Interface is collection of abstract methods which has only declaration and no implementation
include all abstract method
Differences:Abstract class can also contain method definitions but an interface can contain only declarationsAll variables in an interface are by default public static and final whereas in Abstract class it is notAn interface can be considered as a pure abstract class that contains no method implementations and contains only declarations.
Constants and abstract methods. That's it.
Abstraction in Java or Object oriented programming is a way to segregate implementation from interface and one of the five fundamentals along with Encapsulation, Inheritance, Polymorphism, Class and Object. Abstraction in Java is achieved by using interface and abstract class in Java.
interface is just like a class. its contains abstract methods without any implementation and we cant create object for the class. we can only sub classed . used to achieved multiple inheritance in java.
AWT stands for Abstract window tootlkit . Abstract window Toolkit provides a standard application programming interface for writing graphical user interfaces in java.
AWT (Abstract Window Toolkit) is Java's original widget program allowing webmasters to add outside widgets to their sites for users to interface between them and other sites.
They are very different. An abstract class is a class that represents an abstract concept (google define "abstract" if you're unsure) such as 'Thoughts' or 'BankAccount'. When a class is defined as abstract it cannot be used (directly) to create an object. Abstract classes are used as super-classes so that all of their subclasses inherit all methods. Interfaces can be thought of as contracts with all of their implementing classes. They simply require all implementing classes to have methods with the same signature as that defined in the interface, but such methods can behave as appropriate. Hope that helps :)