File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
The moose likes Beginning Java and the fly likes about abstract method and class Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » Beginning Java
Bookmark "about abstract method and class" Watch "about abstract method and class" New topic

about abstract method and class

y bin

Joined: Feb 18, 2004
Posts: 4
I want to determine if the following is correct.
Anybody could discuss it with me?

1,the abstract method's announce need not {} ?
but the abstract method in the abstrct class may have contents({})

2, the abstrct class can't be instantiated, how can I say it has constructor? what is the construtor use?
Leo Deegan

Joined: Jun 15, 2004
Posts: 12
Hey there, y.

1. An abstract method cannot have a block for its body (that is, it can only use a semicolon and cannot use { }).

2. An abstract class can be instantiated, provided its abstract methods are implemented when the class is instantiated. For instance,

public abstract class Abc {
public astract boolean foo();

can be instantiated like this:

Abc abc =
new Abc() {
public boolean foo() {
return false;

One reason for providing a constructor for an abstract class is that its subclasses may take advantage of the constructor.
I agree. Here's the link:
subject: about abstract method and class
It's not a secret anymore!