With this example we are going to demonstrate how to use a final class. In short, to use a final class we have followed the steps below:
- We have created a
finalclassB, that has twointattributes and anAattribute, that is another classA. It also has anf()method. - We create a new instance of
Bclass, and call itsf()method. Then we change the values ofiandjattributes. - The values of the final class can change, but if we try to extend the final class from another one, an error will occur, because classes cannot subclass a final class.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
//remove the comment and see what happens
class A { //extends B{
}
//! class Further extends B {}
// error: Cannot extend final class 'B'
final class B{
int i = 7;
int j = 1;
A x = new A();
void f() {
System.out.println("B.f() function....");
}
}
public class FinalClass {
public static void main(String[] args) {
B n = new B();
n.f();
n.i = 40;
n.j++;
System.out.println("n.i = "+n.i+", n.j = "+n.j);
}
}
Output:
B.f() function....
n.i = 40, n.j = 2
This was an example of how to use a final class in Java.
