[ONOS-2815] add RouterId for Router api

Change-Id: I597dfac4f88a67f1b1f91f469af5950b751554ec

+/*
+ * 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.onosproject.vtnrsc;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.Objects;
+
+/**
+ * Immutable representation of a router identifier.
+ */
+public final class RouterId {
+
+    private final String routerId;
+
+    // Public construction is prohibited
+    private RouterId(String routerId) {
+        checkNotNull(routerId, "routerId cannot be null");
+        this.routerId = routerId;
+    }
+
+    /**
+     * Creates a router identifier.
+     *
+     * @param routerId the router identifier
+     * @return the router identifier
+     */
+    public static RouterId valueOf(String routerId) {
+        return new RouterId(routerId);
+    }
+
+    /**
+     * Returns the router identifier.
+     *
+     * @return the router identifier
+     */
+    public String routerId() {
+        return routerId;
+    }
+
+    @Override
+    public int hashCode() {
+        return routerId.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof RouterId) {
+            final RouterId that = (RouterId) obj;
+            return Objects.equals(this.routerId, that.routerId);
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this).add("routerId", routerId).toString();
+    }
+}
+

+/*
+ * 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.onosproject.vtnrsc.router;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.notNullValue;
+import static org.onlab.junit.ImmutableClassChecker.assertThatClassIsImmutable;
+
+import org.junit.Test;
+import org.onosproject.vtnrsc.RouterId;
+
+import com.google.common.testing.EqualsTester;
+
+/**
+ * Unit tests for RouterId class.
+ */
+public class RouterIdTest {
+    final RouterId routerId1 = RouterId.valueOf("1");
+    final RouterId sameAsRouterId1 = RouterId.valueOf("1");
+    final RouterId routerId2 = RouterId.valueOf("2");
+
+    /**
+     * Checks that the RouterId class is immutable.
+     */
+    @Test
+    public void testImmutability() {
+        assertThatClassIsImmutable(RouterId.class);
+    }
+
+    /**
+     * Checks the operation of equals() methods.
+     */
+    @Test
+    public void testEquals() {
+        new EqualsTester().addEqualityGroup(routerId1, sameAsRouterId1).addEqualityGroup(routerId2)
+                .testEquals();
+    }
+
+    /**
+     * Checks the construction of a RouterId object.
+     */
+    @Test
+    public void testConstruction() {
+        final String routerIdValue = "s";
+        final RouterId routerId = RouterId.valueOf(routerIdValue);
+        assertThat(routerId, is(notNullValue()));
+        assertThat(routerId.routerId(), is(routerIdValue));
+    }
+}