diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/GossipHostStore.java b/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/GossipHostStore.java
index e3d8fe0..ee3fb45 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/GossipHostStore.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/GossipHostStore.java
@@ -399,7 +399,7 @@
     }
 
     // Auxiliary extension to allow location to mutate.
-    private class StoredHost extends DefaultHost {
+    private static final class StoredHost extends DefaultHost {
         private Timestamped<HostLocation> location;
 
         /**
diff --git a/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleHostStore.java b/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleHostStore.java
index ef80b72..ee8570d 100644
--- a/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleHostStore.java
+++ b/core/store/trivial/src/main/java/org/onlab/onos/store/trivial/impl/SimpleHostStore.java
@@ -269,7 +269,7 @@
     }
 
     // Auxiliary extension to allow location to mutate.
-    private class StoredHost extends DefaultHost {
+    private static final class StoredHost extends DefaultHost {
         private HostLocation location;
 
         /**
diff --git a/utils/misc/src/main/java/org/onlab/packet/ChassisId.java b/utils/misc/src/main/java/org/onlab/packet/ChassisId.java
index 5b48e63..4555124 100644
--- a/utils/misc/src/main/java/org/onlab/packet/ChassisId.java
+++ b/utils/misc/src/main/java/org/onlab/packet/ChassisId.java
@@ -32,7 +32,7 @@
      * @param value the value to use.
      */
     public ChassisId(String value) {
-        this.value = Long.valueOf(value, 16);
+        this.value = Long.parseLong(value, 16);
     }
 
     /**
diff --git a/utils/misc/src/main/java/org/onlab/packet/DHCP.java b/utils/misc/src/main/java/org/onlab/packet/DHCP.java
index 2a116b1..119faf9 100644
--- a/utils/misc/src/main/java/org/onlab/packet/DHCP.java
+++ b/utils/misc/src/main/java/org/onlab/packet/DHCP.java
@@ -379,7 +379,7 @@
         // 300
         int optionsLength = 0;
         for (final DHCPOption option : this.options) {
-            if (option.getCode() == 0 || option.getCode() == 255) {
+            if (option.getCode() == 0 || option.getCode() == ((byte) 255)) {
                 optionsLength += 1;
             } else {
                 optionsLength += 2 + (0xff & option.getLength());
diff --git a/utils/misc/src/main/java/org/onlab/packet/IPv4.java b/utils/misc/src/main/java/org/onlab/packet/IPv4.java
index 4b9fd66..634ceff 100644
--- a/utils/misc/src/main/java/org/onlab/packet/IPv4.java
+++ b/utils/misc/src/main/java/org/onlab/packet/IPv4.java
@@ -438,7 +438,7 @@
 
         int result = 0;
         for (int i = 0; i < 4; ++i) {
-            result |= Integer.valueOf(octets[i]) << (3 - i) * 8;
+            result |= Integer.parseInt(octets[i]) << (3 - i) * 8;
         }
         return result;
     }
@@ -471,7 +471,7 @@
         int result = 0;
         for (int i = 0; i < 4; ++i) {
             result = ipAddress >> (3 - i) * 8 & 0xff;
-        sb.append(Integer.valueOf(result).toString());
+        sb.append(result);
         if (i != 3) {
             sb.append(".");
         }
diff --git a/utils/misc/src/main/java/org/onlab/util/HexString.java b/utils/misc/src/main/java/org/onlab/util/HexString.java
index db12aa3..2b91d8e 100644
--- a/utils/misc/src/main/java/org/onlab/util/HexString.java
+++ b/utils/misc/src/main/java/org/onlab/util/HexString.java
@@ -14,7 +14,7 @@
      */
     public static String toHexString(final byte[] bytes) {
         int i;
-        StringBuilder ret = new StringBuilder();
+        StringBuilder ret = new StringBuilder(bytes.length * 3 - 1);
         String tmp;
         for (i = 0; i < bytes.length; i++) {
             if (i > 0) {
@@ -31,22 +31,22 @@
 
     public static String toHexString(final long val, final int padTo) {
         char[] arr = Long.toHexString(val).toCharArray();
-        String ret = "";
+        StringBuilder ret = new StringBuilder(padTo * 3 - 1);
         // 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) != 0) {
-                ret += ":";
+                ret.append(':');
             }
         }
         for (int j = 0; j < arr.length; j++) {
-            ret += arr[j];
+            ret.append(arr[j]);
             if ((((i + j) % 2) != 0) && (j < (arr.length - 1))) {
-                ret += ":";
+                ret.append(':');
             }
         }
-        return ret;
+        return ret.toString();
     }
 
     public static String toHexString(final long val) {
diff --git a/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java b/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java
index 5ef1768..26d835d 100644
--- a/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java
+++ b/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java
@@ -163,6 +163,7 @@
         handlers.putIfAbsent(type, handler);
     }
 
+    @Override
     public void unregisterHandler(String type) {
         handlers.remove(type);
     }
@@ -242,7 +243,7 @@
         }
     }
 
-    private class WriteTask implements Runnable {
+    private static class WriteTask implements Runnable {
 
         private final InternalMessage message;
         private final Channel channel;