scjp question ? what is Au exception here

11. public static void test(String str) { 
12. if(str == null | str.lellgth() == 0) { 
13. System.out.println("String is empty"); 
14. } else { 
15. System.out.println("String is not empty"); 
16. } 
17. } 

And the invocation:

31. test(llull); 

What is the result?

A. Au exception is thrown at runtime.

B. "String is empty" is printed to o开发者_JS百科utput.

C. Compilation fails because of au error in line 12.

D. "String is not empty" is printed to output.

Answer: A

What is Au exception here ? ...

Thanks

---

A. Au exception is thrown at runtime.

if your code is

11. public static void test(String str) { 
12. if(str == null | str.length() == 0) { 
13. System.out.println("String is empty"); 
14. } else { 
15. System.out.println("String is not empty"); 
16. } 
17. }   

and

31. test(null);   

NullPointerException will be thrown at runtime as str will be null and length() will be invoked on null

---

It looks like a typo in whatever test or homework assignment you're doing. It should be "An exception".

---

Im pretty sure you want "||" and not "|" on line 12. And 'lellgth' is spelled 'length'. You might also want to reverse it

  if ( !(str == null) && !(str.trim().length == 0) {
     // string is empty
  } else {
     // string is not empty
  }

because the code as you have it will error out if str is null.

---

The following line will not short circuit:

if(str == null | str.length() == 0) {  

If you use a logical or, it will short circuit (and not test str for null)

if(str == null || str.length() == 0) {  

---

It looks like you have several misprints.

12. if(str == null | str.lellgth() == 0) { 

should be

12. if(str == null | str.legth() == 0) { 

31. test(llull); 

should be

31. test(null); 

And finally,

A. Au exception is thrown at runtime.

should be

A. An exception is thrown at runtime.

---

The exception thrown at runtime will be a NullPointerException because of this line:

if(str == null | str.lellgth() == 0)

The line uses a bitwise or | instead of a logical or ||.