Final Classes, Methods, and Variables - Java Object Oriented Design

Introduction

The final modifier is used with classes, methods, and variables to tell that they will never change.

It has different meanings.

A final class cannot be subclassed.

A final method cannot be overridden by any subclasses.

A final variable cannot change in value.

Final variables are called constants because they do not change in value at any time.

The following statements are examples of declaring constants:

 
public static final int CONST = 6; 
static final String TITLE = "test";

Final methods never can be overridden by a subclass.

public final void getSignature () { 
    // body of method 
}

To disable a class to have subclass, use the final modifier in the class's declaration.

public final class ChatServer { 
    // body of method 
}