openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/core/sal/convertor/common/OrderComparator.java

   1 package org.opendaylight.openflowplugin.openflow.md.core.sal.convertor.common;
   2
   3 import org.opendaylight.yang.gen.v1.urn.opendaylight.action.types.rev131112.Ordered;
   4 import java.util.Comparator;
   5
   6 /**
   7  * Comparator for comparing objects which extend Ordered.
   8  *
   9  * @param <T>
  10  */
  11 public class OrderComparator<T extends Ordered> implements Comparator<T> {
  12
  13     @SuppressWarnings("rawtypes")
  14     private static final OrderComparator INSTANCE = new OrderComparator();
  15
  16     @SuppressWarnings("unchecked")
  17     public static <T extends Ordered> OrderComparator<T> build() {
  18         return INSTANCE;
  19     }
  20
  21     @Override
  22     public int compare(T obj1, T obj2) {
  23         if(obj1 ==null || obj2==null ) {
  24             throw new NullPointerException("Cannot compare null Actions");
  25         } else if (obj1.getOrder() == null) {
  26             throw new NullPointerException(errorMsg(obj1));
  27         } else if (obj2.getOrder() == null) {
  28             throw new NullPointerException(errorMsg(obj2));
  29         }
  30         return obj1.getOrder().compareTo(obj2.getOrder());
  31     }
  32
  33     private String errorMsg(T obj) {
  34         return "The comparing model " + obj + "has getOrder() == null. An order is mandatory";
  35     }
  36 }