title: how can I use string value as an argument?
body: <p>for example:  </p>
  
  <pre><code>&gt;String str="index==1";  
  &gt;int index=1;  
  &gt;if(str)  
  &gt;       System.out.println("1");  
  </code></pre>
  
  <p>what I mean is that the 'if' will use the value of "str" as an argument, and print "1".<br>
  I tryed to look for an answer and I didn't find
  thank you very much!!  </p>