Updated toString methods

* Added toString() in DefaultDeviceInterfaceDescription
* Updated toString() in DefaultTableStatisticsEntry
* Removed unecessary space in DeviceSystemStatisticsQuery

Change-Id: Ib4536d3f10d6c9e2e4805887186e57f5ab321fd8
Signed-off-by: Georgios Katsikas <katsikas.gp@gmail.com>
diff --git a/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceInterfaceDescription.java b/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceInterfaceDescription.java
index f3b38c9..7e5f8e6 100644
--- a/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceInterfaceDescription.java
+++ b/core/api/src/main/java/org/onosproject/net/device/DefaultDeviceInterfaceDescription.java
@@ -22,6 +22,8 @@
 import java.util.List;
 import java.util.Objects;
 
+import static com.google.common.base.MoreObjects.toStringHelper;
+
 /**
  * Basic implementation of description of a legacy device interface.
  */
@@ -127,4 +129,17 @@
     public int hashCode() {
         return Objects.hash(name, mode, vlans, isRateLimited, rateLimit);
     }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .omitNullValues()
+                .add("Device name", name())
+                .add("Device mode", mode())
+                .add("VLAN IDs", vlans())
+                .add("Rate limited", isRateLimited())
+                .add("Rate limit", rateLimit())
+                .toString();
+    }
+
 }
diff --git a/core/api/src/main/java/org/onosproject/net/flow/DefaultTableStatisticsEntry.java b/core/api/src/main/java/org/onosproject/net/flow/DefaultTableStatisticsEntry.java
index e84b343..ccce84e 100644
--- a/core/api/src/main/java/org/onosproject/net/flow/DefaultTableStatisticsEntry.java
+++ b/core/api/src/main/java/org/onosproject/net/flow/DefaultTableStatisticsEntry.java
@@ -16,6 +16,8 @@
 package org.onosproject.net.flow;
 
 import org.onosproject.net.DeviceId;
+import com.google.common.base.MoreObjects.ToStringHelper;
+import static com.google.common.base.MoreObjects.toStringHelper;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
@@ -57,11 +59,21 @@
 
     @Override
     public String toString() {
-        return "device: " + deviceId + ", " +
-                "tableId: " + this.tableId + ", " +
-                "activeEntries: " + this.activeFlowEntries + ", " +
-                "packetsLookedUp: " + this.packetsLookedupCount + ", " +
-                "packetsMatched: " + this.packetsMatchedCount;
+        ToStringHelper toStringHelper = toStringHelper(this);
+        toStringHelper
+            .omitNullValues()
+            .add("Device ID", deviceId)
+            .add("Table ID", tableId)
+            .add("Active entries", activeFlowEntries);
+        if (hasPacketsLookedup()) {
+            toStringHelper.add("Packets looked-up", packetsLookedupCount);
+        }
+        toStringHelper.add("Packets matched", packetsMatchedCount);
+        if (hasMaxSize()) {
+            toStringHelper.add("Max size", maxSize);
+        }
+
+        return toStringHelper.toString();
     }
 
     @Override
@@ -163,4 +175,4 @@
         }
     }
 
-}
\ No newline at end of file
+}