Program might hang

[Kamil Wojcik]

Hi,
I have doubt about question 9 from Self Test (K&B - Chapter 5). I'll put a piece of code:

case 0: {
			for (int x = 10; x > 5; x++)
				if (x > 10000000)
					x = 10;
		}  

Case 0 will initiate an endless loop, so the correct answer is: F - The program might hang without ever completing.
My question is if on the real exam we'll see endless loop in the code, will it be always correct to choose answer that program might hang?
I run that program few times and it's never hang.
Thanks for help!

[Deepak Bala]

I do not have this book with me at this point in time. Can you please post the question in its entirely ?

[Kamil Wojcik]

Give:

   package com.coderanch;

class Infinity {

}

public class Beyond extends Infinity {
	static Integer i;

	public static void main(String[] args) {
		int sw = (int) (Math.random() * 3);
		switch (sw) {
		case 0: {
			for (int x = 10; x > 5; x++)
				if (x > 10000000)
					x = 10;
			break;
		}
		case 1: {
			int y = 7 * i;
			break;
		}
		case 2: {
			Infinity inf = new Beyond();
			Beyond b = (Beyond) inf;
		}
		}
	}
}
 

And given that line 7 will assign the value 0, 1, or 2 to sw, which are true?

A. Compilation fails
B. A ClassCastException might be thrown
C. A StackOverflowError might be thrown
D. A NullPointerException might be thrown
E. An IllegalStateException might be thrown
F. The program might hang without ever completing
G. The program will always complete without exception

[Neha Daga]

D will also be the correct answer because case 1: has expression int y= 7 * i; Since 'i' is an Integer and is never initialized explicitly and its default value is null so a null pointer exception will be thrown.

and as you said F is also a correct answer. So, the answer to this question is D & F.