difference between Abstract class and interface in java

1. An abstract class is a class that is only partially implemented. It may contain none or multiple abstract methods. An abstract method is simply a function definition that must be implemented in a child class.

2. An interface is a fully abstract class; none of its methods are implemented.

3. Variables declared in a Java interface is by default final. An  abstract class may contain non-final variables.

4. An abstract class can have a constructor.

5. Members of a Java interface are public by default. A Java abstract class can have the usual flavors of class members like private, protected, etc..

6. A Java class can implement multiple interfaces but it can extend only one abstract class.