MyWritableComparable.java

public class MyWritableComparable implements WritableComparable<MyWritableComparable> {
  // Some data
  private int counter;
  private long timestamp;
      
  public void write(DataOutput out) throws IOException {
    out.writeInt(counter);
    out.writeLong(timestamp);
  }
      
  public void readFields(DataInput in) throws IOException {
    counter = in.readInt();
    timestamp = in.readLong();
  }
      
  public int compareTo(MyWritableComparable other) {
    int thisValue = this.counter;
    int thatValue = other.counter;
    return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
  }
}