title: I concat string in Java and compared that with itself, equals return false. Why?
body: <p>I've run the following code:</p>
  
  <pre><code> String s1 = "Hello";
   if(s1.equals(s1.concat(" World"))) 
   System.out.println("true");
   else
   System.out.println("false");
  </code></pre>
  
  <p>The output is "false". Why s1 is not equals to itself?</p>