public static class CompositeJoinKeyComparator extends WritableComparator{
 
         protected CompositeJoinKeyComparator(){
              super(CompositeJoinKeyWritable.class, true);
 
         }
 
 
 
         @Override
         public int compare(Object a, Object b) {
 
             CompositeJoinKeyWritable compositeKey1 = (CompositeJoinKeyWritable) a;
             CompositeJoinKeyWritable compositeKey2 = (CompositeJoinKeyWritable) b;
 
             return compositeKey1.getKey().compareTo(compositeKey2.getKey());
 
 
 
         }
     }
 
 
