[T] Java final keyword questions

Java 知识测试 Java final keyword
Question 1
What is the use of final keyword in Java?
A. When a class is made final, a sublcass of it can not be created.
B. When a method is final, it can not be overridden.
C. When a variable is final, it can be assigned value only once.
D. All of the above

Answers

D

Question 2
Output of follwoing Java program

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

A. 20
B. Compiler Error
C. 0
D. Garbage value

Answers

A

Question 3

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

A. 30
B. Compiler Error
C. Garbage value
D. 0

Answers

B

Question 4

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();
    }
}

A. Derived::show() called
B. Base::show() called
C. Compiler Error
D. Exception

Answers

C