| Abstract Class |
Interface |
| Abstract class can have abstract and non-abstract methods. |
Interface can have only abstract methods. |
| Abstract class can have constructor. |
Interface can not have constructor. |
| Abstract class doesn't support multiple inheritance. |
Interface supports multiple inheritance. |
| The abstract keyword is used to declare abstract class. |
The interface keyword is used to declare interface. |
| Abstract class can have final, non-final, static and non-static variables. |
Interface has only static and final variables. |
| Abstract class can provide the implementation of interface. |
Interface can't provide the implementation of abstract class. |
| Calendar class is example of abstract class. |
ActionListener is example of interface. |
Example:
public abstract class Shape{
public abstract void draw();
}
|
Example:
public interface Drawable{
void draw();
}
|
Example of abstract class and interface in Java
// abstract class
abstract class A{
abstract void display();
}
// interface
interface C{
void test();
void disp();
}
// class B that extends A and implements C
class B extends A implements C{
public static void main(String... str){
B b=new B();
// call interface methods
b.disp();
b.test();
// call abstract class method
b.display();
}
public void test(){
System.out.println("test method.");
}
public void disp(){
System.out.println("Disp method.");
}
public void display(){
System.out.println("Display method.");
}
}
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