diff --git a/src/main/java/net/floodlightcontroller/core/internal/Controller.java b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
index 9d4ac9a..44510a7 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/Controller.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
@@ -746,7 +746,7 @@
                     }
                     if (is_core_switch) {
                         sw.setAttribute(IOFSwitch.SWITCH_IS_CORE_SWITCH, 
-                                        new Boolean(true));
+                                        true);
                     }
                 }
                 sw.removeAttribute(IOFSwitch.SWITCH_DESCRIPTION_FUTURE);
@@ -2352,7 +2352,7 @@
                         // new controller node IP
                         addedControllerNodeIPs.put(controllerID, discoveredIP);
                     } 
-                    else if (curIP != discoveredIP) {
+                    else if (curIP.equals(discoveredIP)) {
                         // IP changed                    
                         removedControllerNodeIPs.put(controllerID, curIP);
                         addedControllerNodeIPs.put(controllerID, discoveredIP);
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java
index 4130da6..2c5f4ba 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java
@@ -332,11 +332,7 @@
 		    if ((flowUserState != null)
 			&& flowUserState.equals("FE_USER_DELETE")) {
 			Iterable<IFlowEntry> flowEntries = flowPathObj.getFlowEntries();
-			boolean empty = true;	// TODO: an ugly hack
-			for (IFlowEntry flowEntryObj : flowEntries) {
-			    empty = false;
-			    break;
-			}
+			final boolean empty = !flowEntries.iterator().hasNext();
 			if (empty)
 			    deleteFlows.add(flowPathObj);
 		    }
diff --git a/src/main/java/net/onrc/onos/ofcontroller/linkdiscovery/web/LinksResource.java b/src/main/java/net/onrc/onos/ofcontroller/linkdiscovery/web/LinksResource.java
index c522a05..3c97e6a 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/linkdiscovery/web/LinksResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/linkdiscovery/web/LinksResource.java
@@ -3,6 +3,7 @@
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.Set;
 
 import net.floodlightcontroller.routing.Link;
@@ -23,8 +24,9 @@
 
         if (ld != null) {
             links.putAll(ld.getLinks());
-            for (Link link: links.keySet()) {
-                LinkInfo info = links.get(link);
+            for(Entry<Link, LinkInfo> e : links.entrySet()) {
+                Link link = e.getKey();
+                LinkInfo info = e.getValue();
                 LinkWithType lwt = new LinkWithType(link,
                                                     info.getSrcPortState(),
                                                     info.getDstPortState(),
diff --git a/src/main/java/net/onrc/onos/ofcontroller/util/DataPath.java b/src/main/java/net/onrc/onos/ofcontroller/util/DataPath.java
index dec70e3..e807b56 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/util/DataPath.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/util/DataPath.java
@@ -116,19 +116,18 @@
      * inPort/dpid/outPort;inPort/dpid/outPort;...
      */
     public String dataPathSummary() {
-	String resultStr = new String();
+	StringBuilder resultStr = new StringBuilder(5+1+20+1+5+1);
 	if (this.flowEntries != null) {
 	    for (FlowEntry flowEntry : this.flowEntries) {
 		// The data path summary string
-		resultStr = resultStr +
-		    flowEntry.inPort().toString() + "/"
-		    + flowEntry.dpid().toString() + "/" +
-		    flowEntry.outPort().toString() + ";";
+		resultStr.append(flowEntry.inPort().toString()).append('/')
+			.append(flowEntry.dpid().toString()).append('/')
+			.append(flowEntry.outPort().toString()).append(';');
 	    }
 	}
-	if (resultStr.isEmpty())
-	    resultStr = "X";		// Invalid shortest-path
-	return resultStr;
+	if (resultStr.length() == 0)
+	    resultStr.append("X");		// Invalid shortest-path
+	return resultStr.toString();
     }
 
     /**
diff --git a/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryAction.java b/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryAction.java
index 1f8849a..a1163c8 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryAction.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryAction.java
@@ -48,7 +48,7 @@
     /**
      * Action structure for ACTION_OUTPUT: Output to switch port.
      */
-    public class ActionOutput {
+    public static class ActionOutput {
 	private Port port;	// Output port
 	private short maxLen;	// Max. length (in bytes) to send to controller
 				// if the port is set to PORT_CONTROLLER
@@ -198,7 +198,7 @@
     /**
      * Action structure for ACTION_SET_VLAN_VID: Set the 802.1q VLAN id
      */
-    public class ActionSetVlanId {
+    public static class ActionSetVlanId {
 	private short vlanId;		// The VLAN ID to set
 
 	/**
@@ -296,7 +296,7 @@
     /**
      * Action structure for ACTION_SET_VLAN_PCP: Set the 802.1q priority
      */
-    public class ActionSetVlanPriority {
+    public static class ActionSetVlanPriority {
 	private byte vlanPriority;	// The VLAN priority to set
 
 	/**
@@ -394,7 +394,7 @@
     /**
      * Action structure for ACTION_STRIP_VLAN: Strip the 802.1q header
      */
-    public class ActionStripVlan {
+    public static class ActionStripVlan {
 	private boolean stripVlan;	// If true, strip the VLAN header
 
 	/**
@@ -489,7 +489,7 @@
      * Action structure for ACTION_SET_DL_SRC and ACTION_SET_DL_DST:
      * Set the Ethernet source/destination address.
      */
-    public class ActionSetEthernetAddr {
+    public static class ActionSetEthernetAddr {
 	private MACAddress addr;	// The MAC address to set
 
 	/**
@@ -589,7 +589,7 @@
      * Action structure for ACTION_SET_NW_SRC and ACTION_SET_NW_DST:
      * Set the IPv4 source/destination address.
      */
-    public class ActionSetIPv4Addr {
+    public static class ActionSetIPv4Addr {
 	private IPv4 addr;		// The IPv4 address to set
 
 	/**
@@ -689,7 +689,7 @@
      * Action structure for ACTION_SET_NW_TOS:
      * Set the IP ToS (DSCP field, 6 bits).
      */
-    public class ActionSetIpToS {
+    public static class ActionSetIpToS {
 	private byte ipToS;	// The IP ToS to set DSCP field, 6 bits)
 
 	/**
@@ -788,7 +788,7 @@
      * Action structure for ACTION_SET_TP_SRC and ACTION_SET_TP_DST:
      * Set the TCP/UDP source/destination port.
      */
-    public class ActionSetTcpUdpPort {
+    public static class ActionSetTcpUdpPort {
 	private short port;		// The TCP/UDP port to set
 
 	/**
@@ -886,7 +886,7 @@
     /**
      * Action structure for ACTION_ENQUEUE: Output to queue on port.
      */
-    public class ActionEnqueue {
+    public static class ActionEnqueue {
 	private Port port;	// Port that queue belongs. Should
 				// refer to a valid physical port
 				// (i.e. < PORT_MAX) or PORT_IN_PORT
diff --git a/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryMatch.java b/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryMatch.java
index a721ff2..fd41d09 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryMatch.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/util/FlowEntryMatch.java
@@ -16,7 +16,7 @@
     /**
      * A class for storing a value to match.
      */
-    class Field<T> {
+    static class Field<T> {
 	/**
 	 * Default constructor.
 	 */
diff --git a/src/main/java/net/onrc/onos/ofcontroller/util/FlowPathFlags.java b/src/main/java/net/onrc/onos/ofcontroller/util/FlowPathFlags.java
index 63241f0..4bbd399 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/util/FlowPathFlags.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/util/FlowPathFlags.java
@@ -9,10 +9,10 @@
     private long flags;
 
     // Discard the first-hop Flow Entry
-    private final long DISCARD_FIRST_HOP_ENTRY		= (1 << 0);
+    private static final long DISCARD_FIRST_HOP_ENTRY   = (1 << 0);
 
     // Keep only the first-hop Flow Entry
-    private final long KEEP_ONLY_FIRST_HOP_ENTRY	= (1 << 1);
+    private static final long KEEP_ONLY_FIRST_HOP_ENTRY = (1 << 1);
 
     /**
      * Default constructor.
diff --git a/src/main/java/org/openflow/util/HexString.java b/src/main/java/org/openflow/util/HexString.java
index 5777612..07cc1f7 100644
--- a/src/main/java/org/openflow/util/HexString.java
+++ b/src/main/java/org/openflow/util/HexString.java
@@ -27,35 +27,35 @@
      */
     public static String toHexString(byte[] bytes) {
         int i;
-        String ret = "";
+        StringBuilder ret = new StringBuilder(8*2+7);
         String tmp;
         for(i=0; i< bytes.length; i++) {
             if(i> 0)
-                ret += ":";
+                ret.append(':');
             tmp = Integer.toHexString(U8.f(bytes[i]));
             if (tmp.length() == 1)
-                ret += "0";
-            ret += tmp; 
+                ret.append('0');
+            ret.append(tmp);
         }
-        return ret;
+        return ret.toString();
     }
     
     public static String toHexString(long val, int padTo) {
         char arr[] = Long.toHexString(val).toCharArray();
-        String ret = "";
+        StringBuilder ret = new StringBuilder(8*2+7);
         // prepend the right number of leading zeros
         int i = 0;
         for (; i < (padTo * 2 - arr.length); i++) {
-            ret += "0";
+            ret.append('0');
             if ((i % 2) == 1)
-                ret += ":";
+                ret.append(':');
         }
         for (int j = 0; j < arr.length; j++) {
-            ret += arr[j];
+            ret.append(arr[j]);
             if ((((i + j) % 2) == 1) && (j < (arr.length - 1)))
-                ret += ":";
+                ret.append(':');
         }
-        return ret;        
+        return ret.toString();
     }
    
     public static String toHexString(long val) {
diff --git a/src/test/java/net/onrc/onos/ofcontroller/util/FlowEntryActionTest.java b/src/test/java/net/onrc/onos/ofcontroller/util/FlowEntryActionTest.java
index 4db734c..d816517 100644
--- a/src/test/java/net/onrc/onos/ofcontroller/util/FlowEntryActionTest.java
+++ b/src/test/java/net/onrc/onos/ofcontroller/util/FlowEntryActionTest.java
@@ -19,7 +19,7 @@
 	@Test
 	public void testSetActionOutputActionOutput(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionOutput actout = act.new ActionOutput(new Port((short)42));
+		ActionOutput actout = new FlowEntryAction.ActionOutput(new Port((short)42));
 		act.setActionOutput(actout);
 
 		assertEquals("action output",FlowEntryAction.ActionValues.ACTION_OUTPUT , act.actionType());
@@ -68,7 +68,7 @@
 	@Test
 	public void testSetActionSetVlanIdActionSetVlanId(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionSetVlanId actVlan = act.new ActionSetVlanId((short)42);
+		ActionSetVlanId actVlan = new FlowEntryAction.ActionSetVlanId((short)42);
 		act.setActionSetVlanId(actVlan);
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_VLAN_VID , act.actionType());
@@ -100,7 +100,7 @@
 	@Test
 	public void testSetActionSetVlanPriorityActionSetVlanPriority(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionSetVlanPriority actVlan = act.new ActionSetVlanPriority((byte)42);
+		ActionSetVlanPriority actVlan = new FlowEntryAction.ActionSetVlanPriority((byte)42);
 		act.setActionSetVlanPriority(actVlan);
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_VLAN_PCP , act.actionType());
@@ -132,7 +132,7 @@
 	@Test
 	public void testSetActionStripVlanActionStripVlan(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionStripVlan actVlan = act.new ActionStripVlan();
+		ActionStripVlan actVlan = new FlowEntryAction.ActionStripVlan();
 		act.setActionStripVlan(actVlan);
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_STRIP_VLAN , act.actionType());
@@ -165,7 +165,7 @@
 	public void testSetActionSetEthernetSrcAddrActionSetEthernetAddr(){
 		FlowEntryAction act = new FlowEntryAction();
 		byte[] mac = { 1, 2, 3, 4, 5, 6 };
-		ActionSetEthernetAddr setEth = act.new ActionSetEthernetAddr(new MACAddress(mac));
+		ActionSetEthernetAddr setEth = new FlowEntryAction.ActionSetEthernetAddr(new MACAddress(mac));
 		act.setActionSetEthernetSrcAddr( setEth );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_DL_SRC , act.actionType());
@@ -200,7 +200,7 @@
 	public void testSetActionSetEthernetDstAddrActionSetEthernetAddr(){
 		FlowEntryAction act = new FlowEntryAction();
 		byte[] mac = { 1, 2, 3, 4, 5, 6 };
-		ActionSetEthernetAddr setEth = act.new ActionSetEthernetAddr(new MACAddress(mac));
+		ActionSetEthernetAddr setEth = new FlowEntryAction.ActionSetEthernetAddr(new MACAddress(mac));
 		act.setActionSetEthernetDstAddr( setEth );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_DL_DST , act.actionType());
@@ -233,7 +233,7 @@
 	@Test
 	public void testSetActionSetIPv4SrcAddrActionSetIPv4Addr(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionSetIPv4Addr setIp = act.new ActionSetIPv4Addr(new IPv4("127.0.0.1"));
+		ActionSetIPv4Addr setIp = new FlowEntryAction.ActionSetIPv4Addr(new IPv4("127.0.0.1"));
 		act.setActionSetIPv4SrcAddr( setIp );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_NW_SRC , act.actionType());
@@ -266,7 +266,7 @@
 	@Test
 	public void testSetActionSetIPv4DstAddrActionSetIPv4Addr(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionSetIPv4Addr setIp = act.new ActionSetIPv4Addr(new IPv4("127.0.0.1"));
+		ActionSetIPv4Addr setIp = new FlowEntryAction.ActionSetIPv4Addr(new IPv4("127.0.0.1"));
 		act.setActionSetIPv4DstAddr( setIp );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_NW_DST , act.actionType());
@@ -298,7 +298,7 @@
 	@Test
 	public void testSetActionSetIpToSActionSetIpToS(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionSetIpToS setIpTos = act.new ActionSetIpToS((byte)42);
+		ActionSetIpToS setIpTos = new FlowEntryAction.ActionSetIpToS((byte)42);
 		act.setActionSetIpToS( setIpTos );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_NW_TOS , act.actionType());
@@ -330,7 +330,7 @@
 	@Test
 	public void testSetActionSetTcpUdpSrcPortActionSetTcpUdpPort(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionSetTcpUdpPort setPorts = act.new ActionSetTcpUdpPort((short)42);
+		ActionSetTcpUdpPort setPorts = new FlowEntryAction.ActionSetTcpUdpPort((short)42);
 		act.setActionSetTcpUdpSrcPort( setPorts );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_TP_SRC , act.actionType());
@@ -362,7 +362,7 @@
 	@Test
 	public void testSetActionSetTcpUdpDstPortActionSetTcpUdpPort(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionSetTcpUdpPort setPorts = act.new ActionSetTcpUdpPort((short)42);
+		ActionSetTcpUdpPort setPorts = new FlowEntryAction.ActionSetTcpUdpPort((short)42);
 		act.setActionSetTcpUdpDstPort( setPorts );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_SET_TP_DST , act.actionType());
@@ -394,7 +394,7 @@
 	@Test
 	public void testSetActionEnqueueActionEnqueue(){
 		FlowEntryAction act = new FlowEntryAction();
-		ActionEnqueue enq = act.new ActionEnqueue(new Port((short)42), 1);
+		ActionEnqueue enq = new FlowEntryAction.ActionEnqueue(new Port((short)42), 1);
 		act.setActionEnqueue( enq );
 
 		assertEquals("action type",FlowEntryAction.ActionValues.ACTION_ENQUEUE , act.actionType());