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How many ways are there to initialize a final variable in java?
In Java, final is the access modifier which can be used with a filed, class and a method.
- When a method if final it cannot be overridden.
- When a variable is final its value cannot be modified further.
- When a class is final it cannot be extended.
Initializing a final variable
Once you declare a final variable, it is a must to initialize it. You can initialize the final instance variable −
- At the time of declaration as.
public final String name = "Raju"; public final int age = 20;
- Within an instance (non-static) block.
{
this.name = "Raju";
this.age = 20;
}- Within a default constructor.
public final String name;
public final int age;
public Student(){
this.name = "Raju";
this.age = 20;
}Note − If you try to initialize the final instance variable elsewhere, a compile-time error will be generated.
Example1: At the time of declaration
In the following Java program, the class Student contains two final variables − name, age and, we are initializing them at the time of declaration −
public class Student {
public final String name = "Raju";
public final int age = 20;
public void display(){
System.out.println("Name of the Student: "+this.name );
System.out.println("Age of the Student: "+this.age );
}
public static void main(String args[]) {
new Student().display();
}
}Output
Name of the Student: Raju Age of the Student: 20
Example2: within an instance block
In the following Java program, the class Student contains two final variables− name, age and, we are initializing them within an instance block −
public class Student {
public final String name;
public final int age; {
this.name = "Raju";
this.age = 20;
}
public void display(){
System.out.println("Name of the Student: "+this.name );
System.out.println("Age of the Student: "+this.age );
}
public static void main(String args[]) {
new Student().display();
}
}Output
Name of the Student: Raju Age of the Student: 20
Example3: within the default constructor
In the following Java program, the class Student contains two final variables − name, age and, we are initializing them within a default constructor −
public class Student {
public final String name;
public final int age;
public Student(){
this.name = "Raju";
this.age = 20;
}
public void display(){
System.out.println("Name of the Student: "+this.name );
System.out.println("Age of the Student: "+this.age );
}
public static void main(String args[]) {
new Student().display();
}
}Output
Name of the Student: Raju Age of the Student: 20
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