Implement methods to compare objects in classes representing unit

Methods are added to the following class.
- Bandwidth
- Frequency

To reduce redundant code, RichComparable interface is defined.

Change-Id: Iec96bee9754c6dfca62255b8b4068925d3be13a1

@@ -15,13 +15,15 @@
  */
 package org.onlab.util;
 
+import com.google.common.collect.ComparisonChain;
+
 import java.util.Objects;
 
 /**
  * Representation of bandwidth.
  * Use the static factory method corresponding to the unit (like Kbps) you desire on instantiation.
  */
-public final class Bandwidth {
+public final class Bandwidth implements RichComparable<Bandwidth> {
 
     private final double bps;
 
@@ -89,6 +91,13 @@ public final class Bandwidth {
     }
 
     @Override
+    public int compareTo(Bandwidth other) {
+        return ComparisonChain.start()
+                .compare(this.bps, other.bps)
+                .result();
+    }
+
+    @Override
     public boolean equals(Object obj) {
         if (obj instanceof Bandwidth) {
             Bandwidth that = (Bandwidth) obj;

@@ -16,6 +16,7 @@
 package org.onlab.util;
 
 import com.google.common.base.MoreObjects;
+import com.google.common.collect.ComparisonChain;
 
 import java.util.Objects;
 
@@ -30,7 +31,7 @@ import java.util.Objects;
  * sub-Hz accuracy.
  * </p>
  */
-public final class Frequency {
+public final class Frequency implements RichComparable<Frequency> {
 
     private static final long KHZ = 1_000L;
     private static final long MHZ = 1_000_000L;
@@ -138,6 +139,13 @@ public final class Frequency {
     }
 
     @Override
+    public int compareTo(Frequency other) {
+        return ComparisonChain.start()
+                .compare(this.frequency, other.frequency)
+                .result();
+    }
+
+    @Override
     public int hashCode() {
         return Objects.hash(frequency);
     }

+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onlab.util;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Extends useful methods for comparison to {@link Comparable} interface.
+ *
+ * @param <T> type of instance to be compared
+ */
+public interface RichComparable<T> extends Comparable<T> {
+    /**
+     * Compares if this object is less than the specified object.
+     *
+     * @param other the object to be compared
+     * @return true if this object is less than the specified object
+     */
+    default boolean isLessThan(T other) {
+        return compareTo(checkNotNull(other)) < 0;
+    }
+
+    /**
+     * Compares if this object is greater than the specified object.
+     *
+     * @param other the object to be compared
+     * @return true if this object is less thant the specified object
+     */
+    default boolean isGreaterThan(T other) {
+        return compareTo(checkNotNull(other)) > 0;
+    }
+}

@@ -18,10 +18,19 @@ package org.onlab.util;
 import com.google.common.testing.EqualsTester;
 import org.junit.Test;
 
+import static org.hamcrest.Matchers.greaterThan;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.lessThan;
+import static org.junit.Assert.assertThat;
+
 /**
  * Unit tests for Bandwidth.
  */
 public class BandwidthTest {
+
+    private final Bandwidth small = Bandwidth.kbps(100.0);
+    private final Bandwidth large = Bandwidth.mbps(1.0);
+
     /**
      * Tests equality of Bandwidth instances.
      */
@@ -33,4 +42,21 @@ public class BandwidthTest {
                 .testEquals();
     }
 
+    /**
+     * Tests if the first object is less than the second object.
+     */
+    @Test
+    public void testLessThan() {
+        assertThat(small, is(lessThan(large)));
+        assertThat(small.isLessThan(large), is(true));
+    }
+
+    /**
+     * Tests if the first object is greater than the second object.
+     */
+    @Test
+    public void testGreaterThan() {
+        assertThat(large, is(greaterThan(small)));
+        assertThat(large.isGreaterThan(small), is(true));
+    }
 }

@@ -20,7 +20,9 @@ import org.junit.Test;
 import org.onlab.junit.ImmutableClassChecker;
 
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.lessThan;
 
 public class FrequencyTest {
 
@@ -53,6 +55,21 @@ public class FrequencyTest {
     }
 
     /**
+     * Tests the first object is less than the second object.
+     */
+    @Test
+    public void testLessThan() {
+        assertThat(frequency1, is(lessThan(frequency2)));
+        assertThat(frequency1.isLessThan(frequency2), is(true));
+    }
+
+    @Test
+    public void testGreaterThan() {
+        assertThat(frequency2, is(greaterThan(frequency1)));
+        assertThat(frequency2.isGreaterThan(frequency1), is(true));
+    }
+
+    /**
      * Tests add operation of two Frequencies.
      */
     @Test