Final Keyword in Java
Final Keyword
In this article we will be discussing about Final Keyword in Java.
The Final keyword is used to initialize Constant variables and many more. We can use final with variables, methods and classes.
Final :
The Final keyword is kind of a constant keyword in c++, just like constant, in Java Final keyword is used to initialize constant declaration after which their values can’t be changed throughout the program.
We can initialize following declarations with the help of final keyword:
- variable
- method
- class
Final Variable:
You can declare any final variable using “final” Keyword. you’ll not be able to change this value afterwards throughout the program i.e final variable once initialized with a value can’t be change furthermore.
final int str = "PrepInsta";
import java.util.*;
public class Main{
// class definition
class Prepster{
// defining final variable
final int test = 10;
void change(){
test = 20;
}
public static void main(String[] args){
// Initializing the class object
prepster obj = new prepster();
obj.change();
}
}
Output: Compile Time Error
In Java, a final variable is a variable that once assigned a value, its value cannot be changed. Attempting to change the value of a final variable will result in a compile-time error.
This code will result in a compile-time error with the message: “error: cannot assign a value to final variable test”.
Final Function:
If you are using the final keyword with the method in java, you will not be able to override in the program.
import java.util.*;
// Definition of the class
class Lakshit{
// Final method in java
final void test(){
System.out.print("final Function");
}
}
public class Main{
public static void main(String[] args){
// Initializing the class object
Lakshit obj = new Lakshit();
// Function calling with the help of class object
obj.test();
}
}
Output: final Function
Java Final Class:
if we use Final keyword with class, we’ll not be able to extend it.
import java.util.*;
// final Class definition
final class test {
// function definition
void run(){
System.out.println("test class called");
}
}
public class Main{
public static void main(String[] args){
//Initializing the object of the final class
test obj = new test();
// Calling the run function of final class
obj.run();
}
}
Output: test class called
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