【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
```