android.net.lowpan: Build/syntax fixes and review changes

This commit fixes some build problems that weren't noticed by Tree
Hugger. It also addresses some formatting issues, as well as
corrects a few issues noticed from the last review.

Change-Id: Icab67ba2c40bc02968e3f8ed2da5a4a3be6cf77f

11 files changed, 111 insertions, 134 deletions

diff --git a/lowpan/java/android/net/lowpan/LowpanBeaconInfo.java b/lowpan/java/android/net/lowpan/LowpanBeaconInfo.java
index b344527e4be5..e18abd5bf23f 100644
--- a/lowpan/java/android/net/lowpan/LowpanBeaconInfo.java
+++ b/lowpan/java/android/net/lowpan/LowpanBeaconInfo.java
@@ -26,7 +26,7 @@ import java.util.TreeSet;
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanBeaconInfo extends LowpanIdentity {
 
     private int mRssi = UNKNOWN;
@@ -104,7 +104,7 @@ public class LowpanBeaconInfo extends LowpanIdentity {
     }
 
     public Collection<Integer> getFlags() {
-        return mFlags.clone();
+        return (Collection<Integer>) mFlags.clone();
     }
 
     public boolean isFlagSet(int flag) {
diff --git a/lowpan/java/android/net/lowpan/LowpanChannelInfo.java b/lowpan/java/android/net/lowpan/LowpanChannelInfo.java
index 50afe6d3a4c0..621affee6d06 100644
--- a/lowpan/java/android/net/lowpan/LowpanChannelInfo.java
+++ b/lowpan/java/android/net/lowpan/LowpanChannelInfo.java
@@ -16,14 +16,12 @@
 
 package android.net.lowpan;
 
-
 /** Provides detailed information about a given channel. */
-//@SystemApi
+// @SystemApi
 public class LowpanChannelInfo {
 
     public static final int UNKNOWN_POWER = Integer.MAX_VALUE;
 
-    //////////////////////////////////////////////////////////////////////////
     // Instance Variables
 
     private String mName = null;
@@ -33,7 +31,6 @@ public class LowpanChannelInfo {
     private float mSpectrumBandwidth = 0.0f;
     private int mMaxTransmitPower = UNKNOWN_POWER;
 
-    //////////////////////////////////////////////////////////////////////////
     // Public Getters and Setters
 
     public String getName() {
diff --git a/lowpan/java/android/net/lowpan/LowpanCommissioningSession.java b/lowpan/java/android/net/lowpan/LowpanCommissioningSession.java
index 9cad00c3415a..1da085ddb294 100644
--- a/lowpan/java/android/net/lowpan/LowpanCommissioningSession.java
+++ b/lowpan/java/android/net/lowpan/LowpanCommissioningSession.java
@@ -30,7 +30,7 @@ import java.net.InetSocketAddress;
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public abstract class LowpanCommissioningSession {
     public LowpanCommissioningSession() {}
 
@@ -39,7 +39,7 @@ public abstract class LowpanCommissioningSession {
      *
      * @hide
      */
-    //@SystemApi
+    // @SystemApi
     public class Callback {
         public void onReceiveFromCommissioner(@NonNull byte[] packet) {};
 
diff --git a/lowpan/java/android/net/lowpan/LowpanCredential.java b/lowpan/java/android/net/lowpan/LowpanCredential.java
index dea4d7888884..ca8602151515 100644
--- a/lowpan/java/android/net/lowpan/LowpanCredential.java
+++ b/lowpan/java/android/net/lowpan/LowpanCredential.java
@@ -16,7 +16,6 @@
 
 package android.net.lowpan;
 
-
 import java.util.Map;
 
 /**
@@ -24,7 +23,7 @@ import java.util.Map;
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanCredential {
 
     public static final int UNSPECIFIED_KEY_INDEX = 0;
@@ -84,8 +83,7 @@ public class LowpanCredential {
     void addToMap(Map<String, Object> parameters) throws LowpanException {
         if (isMasterKey()) {
             LowpanProperties.KEY_NETWORK_MASTER_KEY.putInMap(parameters, getMasterKey());
-            LowpanProperties.KEY_NETWORK_MASTER_KEY_INDEX.putInMap(
-                    parameters, getMasterKeyIndex());
+            LowpanProperties.KEY_NETWORK_MASTER_KEY_INDEX.putInMap(parameters, getMasterKeyIndex());
         } else {
             throw new LowpanException("Unsupported Network Credential");
         }
diff --git a/lowpan/java/android/net/lowpan/LowpanEnergyScanResult.java b/lowpan/java/android/net/lowpan/LowpanEnergyScanResult.java
index c680687d0e09..91ed19c488eb 100644
--- a/lowpan/java/android/net/lowpan/LowpanEnergyScanResult.java
+++ b/lowpan/java/android/net/lowpan/LowpanEnergyScanResult.java
@@ -16,13 +16,12 @@
 
 package android.net.lowpan;
 
-
 /**
  * Describes the result from one channel of an energy scan.
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanEnergyScanResult {
     public static final int UNKNOWN = Integer.MAX_VALUE;
 
diff --git a/lowpan/java/android/net/lowpan/LowpanException.java b/lowpan/java/android/net/lowpan/LowpanException.java
index 8ff37f926899..b43b2fe087e1 100644
--- a/lowpan/java/android/net/lowpan/LowpanException.java
+++ b/lowpan/java/android/net/lowpan/LowpanException.java
@@ -28,7 +28,7 @@ import android.util.AndroidException;
  * @see LowpanInterface
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanException extends AndroidException {
     // Make the eclipse warning about serializable exceptions go away
     private static final long serialVersionUID = 0x31863cbe562b0e11l; // randomly generated
diff --git a/lowpan/java/android/net/lowpan/LowpanIdentity.java b/lowpan/java/android/net/lowpan/LowpanIdentity.java
index 2e7b560fda5e..9be45ef14b98 100644
--- a/lowpan/java/android/net/lowpan/LowpanIdentity.java
+++ b/lowpan/java/android/net/lowpan/LowpanIdentity.java
@@ -24,10 +24,9 @@ import java.util.Map;
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanIdentity {
 
-    //////////////////////////////////////////////////////////////////////////
     // Constants
 
     /** @hide */
@@ -41,11 +40,10 @@ public class LowpanIdentity {
 
     public static final int UNKNOWN = Integer.MAX_VALUE;
 
-    //////////////////////////////////////////////////////////////////////////
     // Builder
 
     /** @hide */
-    //@SystemApi
+    // @SystemApi
     public static class Builder {
         private final LowpanIdentity identity = new LowpanIdentity();
 
@@ -102,7 +100,6 @@ public class LowpanIdentity {
 
     LowpanIdentity() {}
 
-    //////////////////////////////////////////////////////////////////////////
     // Instance Variables
 
     private String mName = null;
@@ -111,7 +108,6 @@ public class LowpanIdentity {
     private int mPanid = UNKNOWN;
     private int mChannel = UNKNOWN;
 
-    //////////////////////////////////////////////////////////////////////////
     // Public Getters and Setters
 
     public String getName() {
@@ -140,12 +136,10 @@ public class LowpanIdentity {
             LowpanProperties.KEY_NETWORK_NAME.putInMap(parameters, networkInfo.getName());
         }
         if (networkInfo.getPanid() != LowpanIdentity.UNKNOWN) {
-            LowpanProperties.KEY_NETWORK_PANID.putInMap(
-                    parameters, networkInfo.getPanid());
+            LowpanProperties.KEY_NETWORK_PANID.putInMap(parameters, networkInfo.getPanid());
         }
         if (networkInfo.getChannel() != LowpanIdentity.UNKNOWN) {
-            LowpanProperties.KEY_CHANNEL.putInMap(
-                    parameters, networkInfo.getChannel());
+            LowpanProperties.KEY_CHANNEL.putInMap(parameters, networkInfo.getChannel());
         }
         if (networkInfo.getXpanid() != null) {
             LowpanProperties.KEY_NETWORK_XPANID.putInMap(parameters, networkInfo.getXpanid());
diff --git a/lowpan/java/android/net/lowpan/LowpanInterface.java b/lowpan/java/android/net/lowpan/LowpanInterface.java
index cd548190fa17..2bb4ecd380f2 100644
--- a/lowpan/java/android/net/lowpan/LowpanInterface.java
+++ b/lowpan/java/android/net/lowpan/LowpanInterface.java
@@ -33,7 +33,7 @@ import java.util.Set;
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanInterface {
     private static final String TAG = LowpanInterface.class.getSimpleName();
 
@@ -170,7 +170,7 @@ public class LowpanInterface {
      *
      * @hide
      */
-    //@SystemApi
+    // @SystemApi
     public abstract static class Callback {
         public void onConnectedChanged(boolean value) {}
 
@@ -244,7 +244,6 @@ public class LowpanInterface {
         LowpanException.throwAsPublicException(t);
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Private Property Helpers
 
     void setProperties(Map properties) throws LowpanException {
@@ -311,10 +310,9 @@ public class LowpanInterface {
 
     boolean getPropertyAsBoolean(LowpanProperty<Boolean> key) throws LowpanException {
         Boolean value = getProperty(key);
-        return (value != null) ? value : 0;
+        return (value != null) ? value : false;
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Public Actions
 
     /**
@@ -424,7 +422,6 @@ public class LowpanInterface {
         }
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Public Getters and Setters
 
     /**
@@ -448,13 +445,13 @@ public class LowpanInterface {
         return "";
     }
 
-  /**
-   * Indicates if the interface is enabled or disabled.
-   *
-   * @see #setEnabled
-   * @see android.net.lowpan.LowpanException#LOWPAN_DISABLED
-   */
-  public boolean isEnabled() {
+    /**
+     * Indicates if the interface is enabled or disabled.
+     *
+     * @see #setEnabled
+     * @see android.net.lowpan.LowpanException#LOWPAN_DISABLED
+     */
+    public boolean isEnabled() {
         try {
             return getPropertyAsBoolean(LowpanProperties.KEY_INTERFACE_ENABLED);
         } catch (LowpanException x) {
@@ -462,16 +459,16 @@ public class LowpanInterface {
         }
     }
 
-  /**
-   * Enables or disables the LoWPAN interface. When disabled, the interface is put into a low-power
-   * state and all commands that require the NCP to be queried will fail with {@link
-   * android.net.lowpan.LowpanException#LOWPAN_DISABLED}.
-   *
-   * @see #isEnabled
-   * @see android.net.lowpan.LowpanException#LOWPAN_DISABLED
-   * @hide
-   */
-  public void setEnabled(boolean enabled) throws LowpanException {
+    /**
+     * Enables or disables the LoWPAN interface. When disabled, the interface is put into a
+     * low-power state and all commands that require the NCP to be queried will fail with {@link
+     * android.net.lowpan.LowpanException#LOWPAN_DISABLED}.
+     *
+     * @see #isEnabled
+     * @see android.net.lowpan.LowpanException#LOWPAN_DISABLED
+     * @hide
+     */
+    public void setEnabled(boolean enabled) throws LowpanException {
         setProperty(LowpanProperties.KEY_INTERFACE_ENABLED, enabled);
     }
 
@@ -628,7 +625,6 @@ public class LowpanInterface {
         setProperties(map);
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Listener Support
 
     /**
@@ -644,7 +640,7 @@ public class LowpanInterface {
     public void registerCallback(@NonNull Callback cb, @Nullable Handler handler) {
         ILowpanInterfaceListener.Stub listenerBinder =
                 new ILowpanInterfaceListener.Stub() {
-                    public void onPropertiesChanged(Map<String, Object> properties) {
+                    public void onPropertiesChanged(Map properties) {
                         Runnable runnable =
                                 new Runnable() {
                                     @Override
@@ -724,36 +720,35 @@ public class LowpanInterface {
      */
     public void unregisterCallback(Callback cb) {
         int hashCode = System.identityHashCode(cb);
-        ILowpanInterfaceListener listenerBinder = mListenerMap.get(hashCode);
+        synchronized (mListenerMap) {
+            ILowpanInterfaceListener listenerBinder = mListenerMap.get(hashCode);
 
-        if (listenerBinder != null) {
-            synchronized (mListenerMap) {
+            if (listenerBinder != null) {
                 mListenerMap.remove(hashCode);
-            }
-            try {
-                mBinder.removeListener(listenerBinder);
-            } catch (RemoteException x) {
-                // Catch and ignore all binder exceptions
-                Log.e(TAG, x.toString());
+
+                try {
+                    mBinder.removeListener(listenerBinder);
+                } catch (RemoteException x) {
+                    // Catch and ignore all binder exceptions
+                    Log.e(TAG, x.toString());
+                }
             }
         }
     }
 
-  //////////////////////////////////////////////////////////////////////////
-  // Active and Passive Scanning
+    // Active and Passive Scanning
 
-  /**
-   * Creates a new {@link android.net.lowpan.LowpanScanner} object for this interface.
-   *
-   * <p>This method allocates a new unique object for each call.
-   *
-   * @see android.net.lowpan.LowpanScanner
-   */
-  public @NonNull LowpanScanner createScanner() {
+    /**
+     * Creates a new {@link android.net.lowpan.LowpanScanner} object for this interface.
+     *
+     * <p>This method allocates a new unique object for each call.
+     *
+     * @see android.net.lowpan.LowpanScanner
+     */
+    public @NonNull LowpanScanner createScanner() {
         return new LowpanScanner(mBinder);
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Route Management
 
     /**
diff --git a/lowpan/java/android/net/lowpan/LowpanManager.java b/lowpan/java/android/net/lowpan/LowpanManager.java
index b58608da7c21..ecdda49f718a 100644
--- a/lowpan/java/android/net/lowpan/LowpanManager.java
+++ b/lowpan/java/android/net/lowpan/LowpanManager.java
@@ -33,32 +33,24 @@ import java.util.HashMap;
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanManager {
     private static final String TAG = LowpanManager.class.getSimpleName();
 
-    //////////////////////////////////////////////////////////////////////////
-    // Public Classes
-
     /** @hide */
-    //@SystemApi
+    // @SystemApi
     public abstract static class Callback {
-        public void onInterfaceAdded(LowpanInterface lowpan_interface) {}
+        public void onInterfaceAdded(LowpanInterface lowpanInterface) {}
 
-        public void onInterfaceRemoved(LowpanInterface lowpan_interface) {}
+        public void onInterfaceRemoved(LowpanInterface lowpanInterface) {}
     }
 
-    //////////////////////////////////////////////////////////////////////////
-    // Instance Variables
-
+    private Context mContext;
     private ILowpanManager mManager;
     private HashMap<Integer, ILowpanManagerListener> mListenerMap = new HashMap<>();
 
-    //////////////////////////////////////////////////////////////////////////
-
     private static LowpanManager sSingletonInstance;
 
-    //////////////////////////////////////////////////////////////////////////
     // Static Methods
 
     /** Returns a reference to the LowpanManager object, allocating it if necessary. */
@@ -75,7 +67,6 @@ public class LowpanManager {
         return sSingletonInstance;
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Constructors
 
     /**
@@ -84,28 +75,34 @@ public class LowpanManager {
      */
     private LowpanManager() {}
 
-    //////////////////////////////////////////////////////////////////////////
     // Private Methods
 
     /**
      * Returns a reference to the ILowpanManager interface, provided by the LoWPAN Manager Service.
      */
     @Nullable
-    private ILowpanManager getILowpanManager() {
+    private synchronized ILowpanManager getILowpanManager() {
+        // Use a local reference of this object for thread safety.
         ILowpanManager manager = mManager;
+
         if (manager == null) {
             IBinder serviceBinder =
                     new ServiceManager().getService(ILowpanManager.LOWPAN_SERVICE_NAME);
-            mManager = manager = ILowpanManager.Stub.asInterface(serviceBinder);
+
+            manager = ILowpanManager.Stub.asInterface(serviceBinder);
+
+            mManager = manager;
 
             // Add any listeners
             synchronized (mListenerMap) {
-                for (Integer hashObj : mListenerMap.keySet()) {
+                for (ILowpanManagerListener listener : mListenerMap.values()) {
                     try {
-                        manager.addListener(mListenerMap.get(hashObj));
+                        manager.addListener(listener);
+
                     } catch (RemoteException x) {
                         // Consider any failure here as implying the manager is defunct
-                        mManager = manager = null;
+                        mManager = null;
+                        manager = null;
                     }
                 }
             }
@@ -113,7 +110,6 @@ public class LowpanManager {
         return manager;
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Public Methods
 
     /**
@@ -141,6 +137,7 @@ public class LowpanManager {
                 manager = getILowpanManager();
             }
         }
+
         return ret;
     }
 
@@ -151,7 +148,7 @@ public class LowpanManager {
     @Nullable
     public LowpanInterface getInterface() {
         String[] ifaceList = getInterfaceList();
-        if (ifaceList != null && ifaceList.length > 0) {
+        if (ifaceList.length > 0) {
             return getInterface(ifaceList[0]);
         }
         return null;
@@ -165,24 +162,16 @@ public class LowpanManager {
     public String[] getInterfaceList() {
         ILowpanManager manager = getILowpanManager();
 
-        if (manager != null) {
+        // Maximum number of tries is two. We should only try
+        // more than once if our manager has died or there
+        // was some sort of AIDL buffer full event.
+        for (int i = 0; i < 2 && manager != null; i++) {
             try {
                 return manager.getInterfaceList();
-
             } catch (RemoteException x) {
                 // In all of the cases when we get this exception, we reconnect and try again
                 mManager = null;
-                try {
-                    manager = getILowpanManager();
-                    if (manager != null) {
-                        return manager.getInterfaceList();
-                    }
-                } catch (RemoteException ex) {
-                    // Something weird is going on, so we log it
-                    // and fall back thru to returning an empty array.
-                    Log.e(TAG, ex.toString());
-                    mManager = null;
-                }
+                manager = getILowpanManager();
             }
         }
 
@@ -200,14 +189,14 @@ public class LowpanManager {
             throws LowpanException {
         ILowpanManagerListener.Stub listenerBinder =
                 new ILowpanManagerListener.Stub() {
-                    public void onInterfaceAdded(ILowpanInterface lowpan_interface) {
+                    public void onInterfaceAdded(ILowpanInterface lowpanInterface) {
                         Runnable runnable =
                                 new Runnable() {
                                     @Override
                                     public void run() {
                                         cb.onInterfaceAdded(
                                                 LowpanInterface.getInterfaceFromBinder(
-                                                        lowpan_interface.asBinder()));
+                                                        lowpanInterface.asBinder()));
                                     }
                                 };
 
@@ -218,14 +207,14 @@ public class LowpanManager {
                         }
                     }
 
-                    public void onInterfaceRemoved(ILowpanInterface lowpan_interface) {
+                    public void onInterfaceRemoved(ILowpanInterface lowpanInterface) {
                         Runnable runnable =
                                 new Runnable() {
                                     @Override
                                     public void run() {
                                         cb.onInterfaceRemoved(
                                                 LowpanInterface.getInterfaceFromBinder(
-                                                        lowpan_interface.asBinder()));
+                                                        lowpanInterface.asBinder()));
                                     }
                                 };
 
diff --git a/lowpan/java/android/net/lowpan/LowpanProvision.java b/lowpan/java/android/net/lowpan/LowpanProvision.java
index ace1f9c05c4d..7028807679a1 100644
--- a/lowpan/java/android/net/lowpan/LowpanProvision.java
+++ b/lowpan/java/android/net/lowpan/LowpanProvision.java
@@ -25,14 +25,13 @@ import java.util.Map;
  *
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanProvision {
 
-    //////////////////////////////////////////////////////////////////////////
     // Builder
 
     /** @hide */
-    //@SystemApi
+    // @SystemApi
     public static class Builder {
         private final LowpanProvision provision = new LowpanProvision();
 
@@ -53,13 +52,11 @@ public class LowpanProvision {
 
     private LowpanProvision() {}
 
-    //////////////////////////////////////////////////////////////////////////
     // Instance Variables
 
     private LowpanIdentity mIdentity = new LowpanIdentity();
     private LowpanCredential mCredential = null;
 
-    //////////////////////////////////////////////////////////////////////////
     // Public Getters and Setters
 
     @NonNull
@@ -72,7 +69,6 @@ public class LowpanProvision {
         return mCredential;
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // LoWPAN-Internal Methods
 
     static void addToMap(Map<String, Object> parameters, LowpanProvision provision)
diff --git a/lowpan/java/android/net/lowpan/LowpanScanner.java b/lowpan/java/android/net/lowpan/LowpanScanner.java
index 754f72e3cb84..e0df55d9af3f 100644
--- a/lowpan/java/android/net/lowpan/LowpanScanner.java
+++ b/lowpan/java/android/net/lowpan/LowpanScanner.java
@@ -25,7 +25,6 @@ import android.util.Log;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 /**
@@ -36,11 +35,10 @@ import java.util.Map;
  * @see LowpanInterface
  * @hide
  */
-//@SystemApi
+// @SystemApi
 public class LowpanScanner {
     private static final String TAG = LowpanInterface.class.getSimpleName();
 
-    //////////////////////////////////////////////////////////////////////////
     // Public Classes
 
     /**
@@ -48,7 +46,7 @@ public class LowpanScanner {
      *
      * @hide
      */
-    //@SystemApi
+    // @SystemApi
     public abstract static class Callback {
         public void onNetScanBeacon(LowpanBeaconInfo beacon) {}
 
@@ -57,16 +55,14 @@ public class LowpanScanner {
         public void onScanFinished() {}
     }
 
-    //////////////////////////////////////////////////////////////////////////
     // Instance Variables
 
     private ILowpanInterface mBinder;
     private Callback mCallback = null;
     private Handler mHandler = null;
-    private List<Integer> mChannelMask = null;
+    private ArrayList<Integer> mChannelMask = null;
     private int mTxPower = Integer.MAX_VALUE;
 
-    //////////////////////////////////////////////////////////////////////////
     // Constructors/Accessors and Exception Glue
 
     LowpanScanner(@NonNull ILowpanInterface binder) {
@@ -74,7 +70,7 @@ public class LowpanScanner {
     }
 
     /** Sets an instance of {@link LowpanScanner.Callback} to receive events. */
-    public void setCallback(@Nullable Callback cb, @Nullable Handler handler) {
+    public synchronized void setCallback(@Nullable Callback cb, @Nullable Handler handler) {
         mCallback = cb;
         mHandler = handler;
     }
@@ -110,7 +106,7 @@ public class LowpanScanner {
      * @return the current channel mask, or <code>null</code> if no channel mask is currently set.
      */
     public @Nullable Collection<Integer> getChannelMask() {
-        return mChannelMask.clone();
+        return (Collection<Integer>) mChannelMask.clone();
     }
 
     /**
@@ -179,17 +175,24 @@ public class LowpanScanner {
         ILowpanNetScanCallback binderListener =
                 new ILowpanNetScanCallback.Stub() {
                     public void onNetScanBeacon(Map parameters) {
-                        Callback callback = mCallback;
-                        Handler handler = mHandler;
+                        Callback callback;
+                        Handler handler;
+
+                        synchronized (LowpanScanner.this) {
+                            callback = mCallback;
+                            handler = mHandler;
+                        }
 
                         if (callback == null) {
                             return;
                         }
 
-                        Runnable runnable = () -> callback.onNetScanBeacon(
-                                new LowpanBeaconInfo.Builder()
-                                        .updateFromMap(parameters)
-                                        .build());
+                        Runnable runnable =
+                                () ->
+                                        callback.onNetScanBeacon(
+                                                new LowpanBeaconInfo.Builder()
+                                                        .updateFromMap(parameters)
+                                                        .build());
 
                         if (handler != null) {
                             handler.post(runnable);
@@ -199,8 +202,13 @@ public class LowpanScanner {
                     }
 
                     public void onNetScanFinished() {
-                        Callback callback = mCallback;
-                        Handler handler = mHandler;
+                        Callback callback;
+                        Handler handler;
+
+                        synchronized (LowpanScanner.this) {
+                            callback = mCallback;
+                            handler = mHandler;
+                        }
 
                         if (callback == null) {
                             return;
@@ -218,7 +226,7 @@ public class LowpanScanner {
 
         try {
             mBinder.startNetScan(map, binderListener);
-        } catch (ServiceSpecificException|RemoteException x) {
+        } catch (ServiceSpecificException | RemoteException x) {
             LowpanException.throwAsPublicException(x);
         }
     }
@@ -257,7 +265,8 @@ public class LowpanScanner {
                             return;
                         }
 
-                        Runnable runnable = () -> {
+                        Runnable runnable =
+                                () -> {
                                     if (callback != null) {
                                         LowpanEnergyScanResult result =
                                                 new LowpanEnergyScanResult();