【笔试题】Java final keyword

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

参考答案

``` 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

参考答案

``` 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

参考答案

``` 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

参考答案

``` C ```