title: indexOf method asking for a char that appears multiple times?
body: <pre><code> String str = "Aardvark";
   str.indexOf('a'); 
  </code></pre>
  
  <p>I was wondering what index str would return if it asked for a certain character and the string contained multiple of it. For example, aardvark: would the method return index 0, for the first instance it saw the char? There are 3 'a' chars in the word, so which would it return?</p>
  
  <p>One additional question (couldn't fit it in the original question)
  What is the difference between </p>
  
  <pre><code> str.indexOf('a');
  </code></pre>
  
  <p>and </p>
  
  <pre><code> str.indexOf("a");
  </code></pre>
  
  <p>I know the first is a char and the second is a String, but if str = "Aardvark", wouldn't the second statement return -1 or some sort of error, because "a" refers to a single-character String, not one char of a string? </p>
  
  <p>I'm very sorry if this was unclear, I couldn't really think of a better way to pose my question. Thanks in advance!</p>