Interface Versus Abstract Classes

Difference Between Interface and Abstract Class:

Interface	Abstract Class
1.       If we don’t know anything about implementation just we have requirement specification, then we can use Interface	If we know partial Implementation(not full) then we can use Abstract Class.
2.       Every Method in interface is public abstract, that why interface is Pure abstract class (100%).	In addition to the abstract method Abstract class can also have Non abstract Method(concrete method).
3.       Methods in interface are public and abstract modifiers we can’t use private,protected,final,static,synchronized,native and strictfp modifiers.	There is no restriction for Methods modifiers in  Abstract class.
4.       By Implicitly, variable in interface will be public static final.	In abstract class the variable can be of any data types.
5.       Since variables in interface is public static final we can’t use as private or protected ,transient or volatile modifiers.	There is no restriction for Variable in Abstract class
6.       We should assign the value to variable at the time of declaration otherwise compiler will give error. public static final int x=3;	There is no such restriction in Abstract class.
7.       We can’t declare any instance or static method inside the interface.	Can have instance or static method inside the abstract class.
8.       We can’t have constructor inside the interface, since the variable is static	We can have constructor inside the Abstract class.
9.       Interface can extend more than one interface, Interface C extends A,B	Abstract class can extend class or Abstract class
10.   Interface Car{ public static final int x=10; public int speed(); }	abstract class Engine{                                                                    public abstract void engineType(String carType);  public String engineColor(){          return "red";                                           }