Custom Comparators

You can use your own custom RawComparator for comparing a field in a Tuple. This can be specified in the sort by configuration, for example:

 cg.setOrderBy(new SortBy().add("word", Order.DESC, new MyUtf8Comparator()));

Example:

 private static class MyUtf8Comparator implements RawComparator<Text>, Serializable {
   public int compare(Text arg0, Text arg1) {
     throw new NotImplementedException();
   }

   public int compare(byte[] buf1, int off1, int len1, byte[] buf2, int off2, int len2) {
     if(len1 > len2) {
       return 1;
     } else if(len1 < len2) {
       return -1;
     } else {
       return 0;
     }
   }
 }

In case that you need to deserialize your object in order to compare it, you can subclass BaseComparator and then just compare objects.
For instance, let's define a Thrift object whose definition is :

 struct MyThriftObject {
   1: string userName,
   2: int age
 }

Then your custom comparator could look like this:

 public class MyThriftComparator extends BaseComparator<MyThriftObject> {

   public MyThriftComparator(){
     super(Type.OBJECT,MyThriftObject.class);   
   }
  
   public int compare(MyThriftObject a, MyThriftObject b){
     return a.getUserName().compareTo(b.getUserName());
   }
 }

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