Win a copy of Spring Boot in Practice this week in the Spring forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Tim Cooke
  • Ron McLeod
  • Jeanne Boyarsky
  • Paul Clapham
Sheriffs:
  • Liutauras Vilda
  • Henry Wong
  • Devaka Cooray
Saloon Keepers:
  • Tim Moores
  • Stephan van Hulst
  • Tim Holloway
  • Al Hobbs
  • Carey Brown
Bartenders:
  • Piet Souris
  • Mikalai Zaikin
  • Himai Minh

abstract class

 
Ranch Hand
Posts: 64
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
an abstract class cannot b instiated -- this is true
then in the code below- static A a1 = new A(2){....} -- how come holds.
pls clerefy.......
abstract class A {
private int x = 4;
private int y = 2;
public A(int i1) {x=i1;}
public int x() {return x;}
public void x(int x) {this.x = x;}
public int y() {return y;}
public void y(int y) {this.y = y;}
public void incY() {y++;}
public abstract int math();
}
class B {
static A a1 = new A(2) {
{incY();}
public int math() {return x()+y();}
};
public static void main(String[] args) {
System.out.print(a1.math());
}
}
 
Ranch Hand
Posts: 1561
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
static A a1 = new A(2) {..
This looks like if you were creating an instance of A. But in reality, it's only a subclass of A. When you have an anonymous inner class, your either creating an on-the-fly subclass of a class or implementing an interface.
In this case, your anonymous inner class is implementing the abstract method from class A.
HTH
 
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.
reply
    Bookmark Topic Watch Topic
  • New Topic