title: Difference between String s=" " and String s=null
body: <p>I wrote the program to reverse the string</p>
  
  <pre><code>String original = "hello";
  String rev = "";
  for (int i = original.length() - 1; i &gt;= 0; i--) {
      rev += original.charAt(i);
  }
  System.out.println("Reversal:" + rev);
  </code></pre>
  
  <p>The output is : <code>Reversal:olleh</code></p>
  
  <p>But, when I rewrite <code>String rev=""</code> as <code>String rev =null</code></p>
  
  <p>I get the output as <code>Reversal:nullolleh</code></p>
  
  <p>What is the difference between <code>null</code> and <code>""</code> character?</p>