Java final keyword

Question 1

What is the use of final keyword in Java?

• When a class is made final, a subclass of it can not be created.

• When a method is final, it can not be overridden.

• When a variable is final, it can be assigned value only once.

• All of the above

Question 2

Output of following Java program

Java

class Main {
 public static void main(String args[]){
   final int i;
   i = 20;
   System.out.println(i);
 }
}

• 20
• Compiler Error
• 0
• Garbage value

Question 3

Java

class Main {
 public static void main(String args[]){
    final int i;
    i = 20;
    i = 30;
    System.out.println(i);
 }
}

• 30
• Compiler Error
• Garbage value
• 0

Question 4

Java

class Base {
  public final void show() {
       System.out.println(\"Base::show() called\");
    }
}
class Derived extends Base {
    public void show() {  
       System.out.println(\"Derived::show() called\");
    }
}
public class Main {
    public static void main(String[] args) {
        Base b = new Derived();;
        b.show();
    }
}

• Derived::show() called
• Base::show() called
• Compiler Error
• Exception