Interface methods are implicitly abstract and don't have implementations. A Java abstract class may have instance methods that implements a default behavior. It means that interface is a pure abstract class which have no instance methods at all.
Interface variable are by default final. An abstract class may contain non-final variables.
Interface methods and variables are public by default. A Java abstract class can have the usual flavors of class members like private, protected, etc..
Interface in java should be implemented using keyword “implements”; A Java abstract class should be extended using keyword “extends” just like other classes.
Interface can extend another interface only and it cannot cannot extend or implement a class, an abstract class can extend another Java class and can implement multiple Java interfaces.
A Java class can implement multiple interfaces but it can extend only one abstract class.
Interface is absolutely abstract and cannot be instantiated; A Java abstract class also cannot be instantiated, but can be invoked if a main() exists.
In comparison with java abstract classes, java interfaces are slow as it requires extra indirection.
Interface facilitate programer to achieve multiple inheritance while abstract class don't provide multiple inheritance.
thanks very nice. Today I came to know the exact difference between abstract class and interface.
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