title: Java/Android API understanding
body: <p>I started working on Android applications and I find little difficult to understand this piece of code:</p>
  
  <pre><code>LineNumberReader(new FileReader("/proc/tty/drivers"));   
  </code></pre>
  
  <p>How can I know that the <em>LineNumberReader</em> function accepts <em>FileReader</em> as a new instance of the class?  I went through the Java documentation for the <em>LineNumberReader</em> API, it doesn't mention anything regarding <em>FileReader</em> class.  There is problem in Java API interpretation which I have to consider, Can any one of you please help me in understanding how an API should be used in Java?</p>