title: Find unique and duplicate value
body: <p>In <strong>cells1</strong> I have list of value i.e. [4000,4001,4002,4003] and in <strong>cells2</strong> having i.e [1234,4000]. I am trying to find duplicates and unique value but even its having duplicate value its every time going to else part. why any code wrong .</p>
  
  <pre><code>Iterator itr = cells2.iterator();
      while(itr.hasNext()){
        HSSFCell s = (HSSFCell) itr.next();
        boolean sta = cells1.contains(s.getStringCellValue());
          if(sta==true){
          System.out.println("Dublicate:&gt;&gt;&gt;&gt;"+s.toString());
           }else{
             System.out.println("unique value:&gt;&gt;&gt;&gt;:"+s.toString());
                }
           }
       }
  </code></pre>
  
  <p><strong>out put value is :</strong></p>
  
  <p>unique value:>>>>:1234</p>
  
  <p>unique value:>>>>:4000 <strong>&lt;- which is wrong out put</strong></p>