scjp question ? what is Au exception here 
<pre><code>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. } 
</code></pre>

<p>And the invocation: </p>

<pre><code>31. test(llull); 
</code></pre>

<blockquote>
  <p>What is the result?<br>
  A. Au exception is thrown at runtime.<br>
  B. "String is empty" is printed to output.<br>
  C. Compilation fails because of au error in line 12.<br>
  D. "String is not empty" is printed to output. </p>
</blockquote>

<p>Answer: A </p>

<p>What is Au exception here ? ...</p>

<p>Thanks</p>
