diff --git a/sdk/src/androidTest/java/com/bugsnag/android/BeforeSendTest.java b/sdk/src/androidTest/java/com/bugsnag/android/BeforeSendTest.java
index b896cbed94..90448e0f02 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/BeforeSendTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/BeforeSendTest.java
@@ -4,6 +4,7 @@
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 
+import android.support.annotation.NonNull;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.filters.SmallTest;
 import android.support.test.runner.AndroidJUnit4;
@@ -30,13 +31,13 @@ public void setUp() throws Exception {
         config = new Configuration("key");
         config.setDelivery(new Delivery() {
             @Override
-            public void deliver(SessionTrackingPayload payload,
-                                Configuration config)
+            public void deliver(@NonNull SessionTrackingPayload payload,
+                                @NonNull Configuration config)
                 throws DeliveryFailureException {}
 
             @Override
-            public void deliver(Report report,
-                                Configuration config)
+            public void deliver(@NonNull Report report,
+                                @NonNull Configuration config)
                 throws DeliveryFailureException {
                 lastReport = report;
             }
@@ -53,21 +54,21 @@ public void tearDown() throws Exception {
     public void testCallbackOrderPreserved() {
         config.beforeSend(new BeforeSend() {
             @Override
-            public boolean run(Report report) {
+            public boolean run(@NonNull Report report) {
                 result = result + "a";
                 return true;
             }
         });
         config.beforeSend(new BeforeSend() {
             @Override
-            public boolean run(Report report) {
+            public boolean run(@NonNull Report report) {
                 result = result + "b";
                 return true;
             }
         });
         config.beforeSend(new BeforeSend() {
             @Override
-            public boolean run(Report report) {
+            public boolean run(@NonNull Report report) {
                 result = result + "c";
                 return true;
             }
@@ -81,14 +82,14 @@ public boolean run(Report report) {
     public void testCancelReport() {
         config.beforeSend(new BeforeSend() {
             @Override
-            public boolean run(Report report) {
+            public boolean run(@NonNull Report report) {
                 result = result + "a";
                 return true;
             }
         });
         config.beforeSend(new BeforeSend() {
             @Override
-            public boolean run(Report report) {
+            public boolean run(@NonNull Report report) {
                 result = result + "b";
                 return false;
             }
@@ -102,7 +103,7 @@ public boolean run(Report report) {
     public void testAlterReport() {
         config.beforeSend(new BeforeSend() {
             @Override
-            public boolean run(Report report) {
+            public boolean run(@NonNull Report report) {
                 report.getError().setGroupingHash("123");
                 return true;
             }
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java b/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java
index fa9f8612cb..6a6fc3505d 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/BugsnagTestUtils.java
@@ -75,9 +75,9 @@ static SessionStore generateSessionStore() {
     static SessionTrackingApiClient generateSessionTrackingApiClient() {
         return new SessionTrackingApiClient() {
             @Override
-            public void postSessionTrackingPayload(String urlString,
-                                                   SessionTrackingPayload payload,
-                                                   Map<String, String> headers)
+            public void postSessionTrackingPayload(@NonNull String urlString,
+                                                   @NonNull SessionTrackingPayload payload,
+                                                   @NonNull Map<String, String> headers)
                 throws NetworkException, BadResponseException {
 
             }
@@ -88,9 +88,9 @@ public void postSessionTrackingPayload(String urlString,
     static ErrorReportApiClient generateErrorReportApiClient() { // no-op
         return new ErrorReportApiClient() {
             @Override
-            public void postReport(String urlString,
-                                   Report report,
-                                   Map<String, String> headers)
+            public void postReport(@NonNull String urlString,
+                                   @NonNull Report report,
+                                   @NonNull Map<String, String> headers)
                 throws NetworkException, BadResponseException {
 
             }
@@ -100,13 +100,13 @@ public void postReport(String urlString,
     public static Delivery generateDelivery() {
         return new Delivery() {
             @Override
-            public void deliver(SessionTrackingPayload payload,
-                                Configuration config)
+            public void deliver(@NonNull SessionTrackingPayload payload,
+                                @NonNull Configuration config)
                 throws DeliveryFailureException {}
 
             @Override
-            public void deliver(Report report,
-                                Configuration config)
+            public void deliver(@NonNull Report report,
+                                @NonNull Configuration config)
                 throws DeliveryFailureException {}
 
         };
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java b/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java
index f3e2d81ebe..44f49ec33d 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/ClientConfigTest.java
@@ -6,6 +6,7 @@
 import static org.junit.Assert.assertTrue;
 
 import android.content.Context;
+import android.support.annotation.NonNull;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.filters.SmallTest;
 import android.support.test.runner.AndroidJUnit4;
@@ -105,13 +106,13 @@ public void testCustomDeliveryOverride() {
         config = BugsnagTestUtils.generateConfiguration();
         Delivery customDelivery = new Delivery() {
             @Override
-            public void deliver(SessionTrackingPayload payload,
-                                Configuration config)
+            public void deliver(@NonNull SessionTrackingPayload payload,
+                                @NonNull Configuration config)
                 throws DeliveryFailureException {}
 
             @Override
-            public void deliver(Report report,
-                                Configuration config)
+            public void deliver(@NonNull Report report,
+                                @NonNull Configuration config)
                 throws DeliveryFailureException {}
 
         };
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/ClientNotifyTest.java b/sdk/src/androidTest/java/com/bugsnag/android/ClientNotifyTest.java
index 6df29a82a2..c79be5038d 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/ClientNotifyTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/ClientNotifyTest.java
@@ -2,6 +2,7 @@
 
 import static org.junit.Assert.assertEquals;
 
+import android.support.annotation.NonNull;
 import android.support.test.filters.SmallTest;
 import android.support.test.runner.AndroidJUnit4;
 
@@ -49,7 +50,7 @@ public void testNotifyBlockingDefaultSeverity() {
     public void testNotifyBlockingCallback() {
         client.notifyBlocking(new RuntimeException("Testing"), new Callback() {
             @Override
-            public void beforeNotify(Report report) {
+            public void beforeNotify(@NonNull Report report) {
                 report.getError().setUserName("Foo");
             }
         });
@@ -72,7 +73,7 @@ public void testNotifyBlockingCustomStackTrace() {
 
         client.notifyBlocking("Name", "Message", stacktrace, new Callback() {
             @Override
-            public void beforeNotify(Report report) {
+            public void beforeNotify(@NonNull Report report) {
                 report.getError().setSeverity(Severity.ERROR);
             }
         });
@@ -89,9 +90,9 @@ static class FakeClient implements ErrorReportApiClient {
         Report report;
 
         @Override
-        public void postReport(String urlString,
-                               Report report,
-                               Map<String, String> headers)
+        public void postReport(@NonNull String urlString,
+                               @NonNull Report report,
+                               @NonNull Map<String, String> headers)
             throws NetworkException, BadResponseException {
             try {
                 Thread.sleep(10); // simulate async request
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java b/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java
index a946281ba0..83c4b8aadc 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/ClientTest.java
@@ -10,6 +10,7 @@
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.filters.SmallTest;
 import android.support.test.runner.AndroidJUnit4;
@@ -116,7 +117,7 @@ public void testRestoreUserFromPrefs() {
 
         client.beforeNotify(new BeforeNotify() {
             @Override
-            public boolean run(Error error) {
+            public boolean run(@NonNull Error error) {
                 // Pull out the user information
                 user.setId(error.getUser().getId());
                 user.setEmail(error.getUser().getEmail());
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/ConcurrentCallbackTest.java b/sdk/src/androidTest/java/com/bugsnag/android/ConcurrentCallbackTest.java
index 3358881703..3d75c0851a 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/ConcurrentCallbackTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/ConcurrentCallbackTest.java
@@ -36,7 +36,7 @@ public void testClientNotifyModification() throws Exception {
         final Collection<BeforeNotify> beforeNotifyTasks = client.config.getBeforeNotifyTasks();
         client.beforeNotify(new BeforeNotify() {
             @Override
-            public boolean run(Error error) {
+            public boolean run(@NonNull Error error) {
                 beforeNotifyTasks.add(new BeforeNotifySkeleton());
                 // modify the Set, when iterating to the next callback this should not crash
                 return true;
@@ -66,7 +66,7 @@ public boolean shouldRecord(@NonNull Breadcrumb breadcrumb) {
 
     static class BeforeNotifySkeleton implements BeforeNotify {
         @Override
-        public boolean run(Error error) {
+        public boolean run(@NonNull Error error) {
             return true;
         }
     }
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/DeliveryCompatTest.java b/sdk/src/androidTest/java/com/bugsnag/android/DeliveryCompatTest.java
index 26e9f35f1d..177cfc4d88 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/DeliveryCompatTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/DeliveryCompatTest.java
@@ -5,6 +5,8 @@
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
+import android.support.annotation.NonNull;
+
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -38,9 +40,9 @@ public void deliverReport() throws Exception {
 
         deliveryCompat.errorReportApiClient = new ErrorReportApiClient() {
             @Override
-            public void postReport(String urlString,
-                                   Report report,
-                                   Map<String, String> headers)
+            public void postReport(@NonNull String urlString,
+                                   @NonNull Report report,
+                                   @NonNull Map<String, String> headers)
                 throws NetworkException, BadResponseException {
                 customCount.incrementAndGet();
             }
@@ -58,9 +60,9 @@ public void deliverSession() throws Exception {
 
         deliveryCompat.sessionTrackingApiClient = new SessionTrackingApiClient() {
             @Override
-            public void postSessionTrackingPayload(String urlString,
-                                                   SessionTrackingPayload payload,
-                                                   Map<String, String> headers)
+            public void postSessionTrackingPayload(@NonNull String urlString,
+                                                   @NonNull SessionTrackingPayload payload,
+                                                   @NonNull Map<String, String> headers)
                 throws NetworkException, BadResponseException {
                 customCount.incrementAndGet();
             }
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/ErrorReportApiClientTest.java b/sdk/src/androidTest/java/com/bugsnag/android/ErrorReportApiClientTest.java
index a1a7612068..83c5e2d1f2 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/ErrorReportApiClientTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/ErrorReportApiClientTest.java
@@ -3,6 +3,7 @@
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 
+import android.support.annotation.NonNull;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.filters.SmallTest;
 import android.support.test.runner.AndroidJUnit4;
@@ -53,9 +54,9 @@ private static class FakeApiClient implements ErrorReportApiClient {
         private Report report;
 
         @Override
-        public void postReport(String urlString,
-                               Report report,
-                               Map<String, String> headers)
+        public void postReport(@NonNull String urlString,
+                               @NonNull Report report,
+                               @NonNull Map<String, String> headers)
             throws NetworkException, BadResponseException {
             this.report = report;
         }
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/NullMetadataTest.java b/sdk/src/androidTest/java/com/bugsnag/android/NullMetadataTest.java
index a4bdb8cb88..dde426a003 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/NullMetadataTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/NullMetadataTest.java
@@ -5,6 +5,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
+import android.support.annotation.NonNull;
 import android.support.test.InstrumentationRegistry;
 
 import org.junit.After;
@@ -95,7 +96,7 @@ public void testConfigSetNullMetadata() throws Exception {
     public void testNotify() throws Exception {
         Bugsnag.beforeNotify(new BeforeNotify() {
             @Override
-            public boolean run(Error error) {
+            public boolean run(@NonNull Error error) {
                 validateDefaultMetadata(error.getMetaData());
                 return false;
             }
diff --git a/sdk/src/androidTest/java/com/bugsnag/android/UniqueBeforeNotifyTest.java b/sdk/src/androidTest/java/com/bugsnag/android/UniqueBeforeNotifyTest.java
index 28b1b96db0..ec3c97600e 100644
--- a/sdk/src/androidTest/java/com/bugsnag/android/UniqueBeforeNotifyTest.java
+++ b/sdk/src/androidTest/java/com/bugsnag/android/UniqueBeforeNotifyTest.java
@@ -2,6 +2,7 @@
 
 import static org.junit.Assert.assertEquals;
 
+import android.support.annotation.NonNull;
 import android.support.test.filters.SmallTest;
 import android.support.test.runner.AndroidJUnit4;
 
@@ -20,14 +21,14 @@ public class UniqueBeforeNotifyTest {
 
     private BeforeNotify firstCb = new BeforeNotify() {
         @Override
-        public boolean run(Error error) {
+        public boolean run(@NonNull Error error) {
             return handleCallback();
         }
     };
 
     private BeforeNotify secondCb = new BeforeNotify() {
         @Override
-        public boolean run(Error error) {
+        public boolean run(@NonNull Error error) {
             return handleCallback();
         }
     };
@@ -72,7 +73,7 @@ public void testDuplicateCallback() {
     public void testCallbackOrder() {
         client.beforeNotify(new BeforeNotify() {
             @Override
-            public boolean run(Error error) {
+            public boolean run(@NonNull Error error) {
                 assertEquals(0, callbackCount);
                 callbackCount++;
                 return false;
@@ -80,7 +81,7 @@ public boolean run(Error error) {
         });
         client.beforeNotify(new BeforeNotify() {
             @Override
-            public boolean run(Error error) {
+            public boolean run(@NonNull Error error) {
                 assertEquals(1, callbackCount);
                 return false;
             }
diff --git a/sdk/src/main/java/com/bugsnag/android/BlockedThreadDetector.java b/sdk/src/main/java/com/bugsnag/android/BlockedThreadDetector.java
index 949ff992d3..1fcc4cf369 100644
--- a/sdk/src/main/java/com/bugsnag/android/BlockedThreadDetector.java
+++ b/sdk/src/main/java/com/bugsnag/android/BlockedThreadDetector.java
@@ -36,7 +36,6 @@ interface Delegate {
     final long blockedThresholdMs;
     final Handler uiHandler;
     final Handler watchdogHandler;
-    private final HandlerThread watchdogHandlerThread;
     final Delegate delegate;
     final ActivityManager activityManager;
 
@@ -66,7 +65,7 @@ interface Delegate {
         this.uiHandler = new Handler(looper);
         this.activityManager = activityManager;
 
-        watchdogHandlerThread = new HandlerThread("bugsnag-anr-watchdog");
+        HandlerThread watchdogHandlerThread = new HandlerThread("bugsnag-anr-watchdog");
         watchdogHandlerThread.start();
         watchdogHandler = new Handler(watchdogHandlerThread.getLooper());
     }
diff --git a/sdk/src/main/java/com/bugsnag/android/CachedThread.java b/sdk/src/main/java/com/bugsnag/android/CachedThread.java
index 40f15e81e2..8c8048b5d8 100644
--- a/sdk/src/main/java/com/bugsnag/android/CachedThread.java
+++ b/sdk/src/main/java/com/bugsnag/android/CachedThread.java
@@ -8,12 +8,12 @@
  * A representation of a thread recorded in a {@link Report}
  */
 class CachedThread implements JsonStream.Streamable {
-    private long id;
-    private String name;
-    private String type;
-    private boolean isErrorReportingThread;
-    private StackTraceElement[] frames;
-    private Configuration config;
+    private final long id;
+    private final String name;
+    private final String type;
+    private final boolean isErrorReportingThread;
+    private final StackTraceElement[] frames;
+    private final Configuration config;
 
     CachedThread(Configuration config, long id, String name, String type,
                  boolean isErrorReportingThread, StackTraceElement[] frames) {
diff --git a/sdk/src/main/java/com/bugsnag/android/Client.java b/sdk/src/main/java/com/bugsnag/android/Client.java
index c8d3e27c4e..800ac6c761 100644
--- a/sdk/src/main/java/com/bugsnag/android/Client.java
+++ b/sdk/src/main/java/com/bugsnag/android/Client.java
@@ -26,7 +26,6 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Observable;
 import java.util.Observer;
@@ -75,7 +74,7 @@ public class Client extends Observable implements Observer {
 
     final EventReceiver eventReceiver;
     final SessionTracker sessionTracker;
-    SharedPreferences sharedPrefs;
+    final SharedPreferences sharedPrefs;
 
     private final OrientationEventListener orientationListener;
 
diff --git a/sdk/src/main/java/com/bugsnag/android/Configuration.java b/sdk/src/main/java/com/bugsnag/android/Configuration.java
index 0c84adc217..fe7f954997 100644
--- a/sdk/src/main/java/com/bugsnag/android/Configuration.java
+++ b/sdk/src/main/java/com/bugsnag/android/Configuration.java
@@ -8,7 +8,6 @@
 
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
diff --git a/sdk/src/main/java/com/bugsnag/android/DeviceData.java b/sdk/src/main/java/com/bugsnag/android/DeviceData.java
index 611500440a..4bd092eef0 100644
--- a/sdk/src/main/java/com/bugsnag/android/DeviceData.java
+++ b/sdk/src/main/java/com/bugsnag/android/DeviceData.java
@@ -55,19 +55,19 @@ class DeviceData {
     private final boolean rooted;
 
     @Nullable
-    Float screenDensity;
+    final Float screenDensity;
 
     @Nullable
-    Integer dpi;
+    final Integer dpi;
 
     @Nullable
-    String screenResolution;
+    final String screenResolution;
 
     @NonNull
-    String locale;
+    final String locale;
 
     @NonNull
-    String[] cpuAbi;
+    final String[] cpuAbi;
 
     DeviceData(Client client) {
         this.client = client;
diff --git a/sdk/src/main/java/com/bugsnag/android/Error.java b/sdk/src/main/java/com/bugsnag/android/Error.java
index fee59359ac..683b16e003 100644
--- a/sdk/src/main/java/com/bugsnag/android/Error.java
+++ b/sdk/src/main/java/com/bugsnag/android/Error.java
@@ -19,10 +19,10 @@
 public class Error implements JsonStream.Streamable {
 
     @NonNull
-    private Map<String, Object> appData = new HashMap<String, Object>();
+    private Map<String, Object> appData = new HashMap<>();
 
     @NonNull
-    private Map<String, Object> deviceData = new HashMap<String, Object>();
+    private Map<String, Object> deviceData = new HashMap<>();
 
     @NonNull
     private User user = new User();
diff --git a/sdk/src/main/java/com/bugsnag/android/ErrorReader.java b/sdk/src/main/java/com/bugsnag/android/ErrorReader.java
index 91f344940a..44e030dc1d 100644
--- a/sdk/src/main/java/com/bugsnag/android/ErrorReader.java
+++ b/sdk/src/main/java/com/bugsnag/android/ErrorReader.java
@@ -245,7 +245,7 @@ private static StackTraceElement[] readStackFrames(JsonReader reader) throws IOE
             frames.add(readStackFrame(reader));
         }
         reader.endArray();
-        return frames.toArray(new StackTraceElement[frames.size()]);
+        return frames.toArray(new StackTraceElement[0]);
     }
 
     private static StackTraceElement readStackFrame(JsonReader reader) throws IOException {
@@ -290,16 +290,19 @@ private static ArrayList<String> readSeverityReason(JsonReader reader) throws IO
         String type = null;
         String attributeValue = null;
         while (reader.hasNext()) {
-            String name = reader.nextName();
-            if (name.equals("type")) {
-                type = reader.nextString();
-            } else if (name.equals("attributes")) {
-                reader.beginObject();
-                reader.nextName();
-                attributeValue = reader.nextString();
-                reader.endObject();
-            } else {
-                reader.skipValue();
+            switch (reader.nextName()) {
+                case "type":
+                    type = reader.nextString();
+                    break;
+                case "attributes":
+                    reader.beginObject();
+                    reader.nextName();
+                    attributeValue = reader.nextString();
+                    reader.endObject();
+                    break;
+                default:
+                    reader.skipValue();
+                    break;
             }
         }
         reader.endObject();
@@ -324,32 +327,40 @@ private static Session readSession(JsonReader reader) throws IOException {
         User user = null;
         reader.beginObject();
         while (reader.hasNext()) {
-            String name = reader.nextName();
-            if (name.equals("id")) {
-                id = reader.nextString();
-            } else if (name.equals("startedAt")) {
-                try {
-                    startedAt = DateUtils.fromIso8601(reader.nextString());
-                } catch (Exception ex) {
-                    throw new IOException("Unable to parse session startedAt: ", ex);
-                }
-            } else if (name.equals("events")) {
-                reader.beginObject();
-                while (reader.hasNext()) {
-                    String eventName = reader.nextName();
-                    if (eventName.equals("unhandled")) {
-                        unhandled = reader.nextInt();
-                    } else if (eventName.equals("handled")) {
-                        handled = reader.nextInt();
-                    } else {
-                        reader.skipValue();
+            switch (reader.nextName()) {
+                case "id":
+                    id = reader.nextString();
+                    break;
+                case "startedAt":
+                    try {
+                        startedAt = DateUtils.fromIso8601(reader.nextString());
+                    } catch (Exception ex) {
+                        throw new IOException("Unable to parse session startedAt: ", ex);
                     }
-                }
-                reader.endObject();
-            } else if (name.equals("user")) {
-                user = readUser(reader);
-            } else {
-                reader.skipValue();
+                    break;
+                case "events":
+                    reader.beginObject();
+                    while (reader.hasNext()) {
+                        switch (reader.nextName()) {
+                            case "unhandled":
+                                unhandled = reader.nextInt();
+                                break;
+                            case "handled":
+                                handled = reader.nextInt();
+                                break;
+                            default:
+                                reader.skipValue();
+                                break;
+                        }
+                    }
+                    reader.endObject();
+                    break;
+                case "user":
+                    user = readUser(reader);
+                    break;
+                default:
+                    reader.skipValue();
+                    break;
             }
         }
         reader.endObject();
@@ -396,7 +407,7 @@ private static ThreadState readThreadState(Configuration config, JsonReader read
             }
         }
         reader.endArray();
-        return new ThreadState(threads.toArray(new CachedThread[threads.size()]));
+        return new ThreadState(threads.toArray(new CachedThread[0]));
     }
 
     private static CachedThread readThread(Configuration config,
diff --git a/sdk/src/main/java/com/bugsnag/android/EventReceiver.java b/sdk/src/main/java/com/bugsnag/android/EventReceiver.java
index 40820064a3..1d1b51c73d 100644
--- a/sdk/src/main/java/com/bugsnag/android/EventReceiver.java
+++ b/sdk/src/main/java/com/bugsnag/android/EventReceiver.java
@@ -69,7 +69,7 @@ static boolean isAndroidKey(@NonNull String actionName) {
     @NonNull
     static String shortenActionNameIfNeeded(@NonNull String action) {
         if (isAndroidKey(action)) {
-            return action.substring(action.lastIndexOf(".") + 1, action.length());
+            return action.substring(action.lastIndexOf(".") + 1);
         } else {
             return action;
         }
diff --git a/sdk/src/main/java/com/bugsnag/android/Exceptions.java b/sdk/src/main/java/com/bugsnag/android/Exceptions.java
index 5f38888e48..692f51bc20 100644
--- a/sdk/src/main/java/com/bugsnag/android/Exceptions.java
+++ b/sdk/src/main/java/com/bugsnag/android/Exceptions.java
@@ -3,20 +3,16 @@
 import android.support.annotation.NonNull;
 
 import java.io.IOException;
-import java.util.Collections;
-import java.util.List;
 
 /**
  * Unwrap and serialize exception information and any "cause" exceptions.
  */
 class Exceptions implements JsonStream.Streamable {
-    private final Configuration config;
     private final Throwable exception;
     private String exceptionType;
     private String[] projectPackages;
 
     Exceptions(Configuration config, Throwable exception) {
-        this.config = config;
         this.exception = exception;
         exceptionType = Configuration.DEFAULT_EXCEPTION_TYPE;
         projectPackages = config.getProjectPackages();
diff --git a/sdk/src/main/java/com/bugsnag/android/MetaData.java b/sdk/src/main/java/com/bugsnag/android/MetaData.java
index 026bcbdc20..94d81cd5fb 100644
--- a/sdk/src/main/java/com/bugsnag/android/MetaData.java
+++ b/sdk/src/main/java/com/bugsnag/android/MetaData.java
@@ -122,7 +122,7 @@ static MetaData merge(@NonNull MetaData... metaDataList) {
 
         @SuppressWarnings({"unchecked", "rawtypes"})
         MetaData newMeta = new MetaData(mergeMaps(stores.toArray(new Map[0])));
-        newMeta.setFilters(filters.toArray(new String[filters.size()]));
+        newMeta.setFilters(filters.toArray(new String[0]));
 
         return newMeta;
     }
diff --git a/sdk/src/main/java/com/bugsnag/android/Session.java b/sdk/src/main/java/com/bugsnag/android/Session.java
index 882500cf6c..8eb88b204c 100644
--- a/sdk/src/main/java/com/bugsnag/android/Session.java
+++ b/sdk/src/main/java/com/bugsnag/android/Session.java
@@ -12,7 +12,7 @@ class Session implements JsonStream.Streamable {
     private final String id;
     private final Date startedAt;
     private final User user;
-    private AtomicBoolean autoCaptured;
+    private final AtomicBoolean autoCaptured;
 
     static Session copySession(Session session) {
         Session copy = new Session(session.id, session.startedAt,
diff --git a/sdk/src/main/java/com/bugsnag/android/SessionTracker.java b/sdk/src/main/java/com/bugsnag/android/SessionTracker.java
index f559650470..085efe2149 100644
--- a/sdk/src/main/java/com/bugsnag/android/SessionTracker.java
+++ b/sdk/src/main/java/com/bugsnag/android/SessionTracker.java
@@ -38,12 +38,12 @@ class SessionTracker extends Observable implements Application.ActivityLifecycle
     final SessionStore sessionStore;
 
     // This most recent time an Activity was stopped.
-    private AtomicLong lastExitedForegroundMs = new AtomicLong(0);
+    private final AtomicLong lastExitedForegroundMs = new AtomicLong(0);
 
     // The first Activity in this 'session' was started at this time.
-    private AtomicLong lastEnteredForegroundMs = new AtomicLong(0);
-    private AtomicReference<Session> currentSession = new AtomicReference<>();
-    private Semaphore flushingRequest = new Semaphore(1);
+    private final AtomicLong lastEnteredForegroundMs = new AtomicLong(0);
+    private final AtomicReference<Session> currentSession = new AtomicReference<>();
+    private final Semaphore flushingRequest = new Semaphore(1);
 
     SessionTracker(Configuration configuration, Client client, SessionStore sessionStore) {
         this(configuration, client, DEFAULT_TIMEOUT_MS, sessionStore);
diff --git a/sdk/src/main/java/com/bugsnag/android/Stacktrace.java b/sdk/src/main/java/com/bugsnag/android/Stacktrace.java
index a3c2cf5f9b..ff136c274b 100644
--- a/sdk/src/main/java/com/bugsnag/android/Stacktrace.java
+++ b/sdk/src/main/java/com/bugsnag/android/Stacktrace.java
@@ -3,7 +3,6 @@
 import android.support.annotation.NonNull;
 
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
diff --git a/sdk/src/main/java/com/bugsnag/android/ThreadState.java b/sdk/src/main/java/com/bugsnag/android/ThreadState.java
index 8e89ab1967..9f4c57c8ae 100644
--- a/sdk/src/main/java/com/bugsnag/android/ThreadState.java
+++ b/sdk/src/main/java/com/bugsnag/android/ThreadState.java
@@ -6,7 +6,6 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Comparator;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
 
@@ -20,9 +19,8 @@ class ThreadState implements JsonStream.Streamable {
 
     public ThreadState(@NonNull Configuration config,
                        @NonNull Thread currentThread,
-                       @NonNull Map<Thread, StackTraceElement[]> allStackTraces,
+                       @NonNull Map<Thread, StackTraceElement[]> stackTraces,
                        @Nullable Throwable exc) {
-        Map<Thread, StackTraceElement[]> stackTraces = allStackTraces;
 
         // API 24/25 don't record the currentThread, add it in manually
         // https://issuetracker.google.com/issues/64122757
@@ -56,7 +54,7 @@ public ThreadState(@NonNull Configuration config,
     private Thread[] sortThreadsById(Map<Thread, StackTraceElement[]> liveThreads) {
         Set<Thread> threadSet = liveThreads.keySet();
 
-        Thread[] threads = threadSet.toArray(new Thread[threadSet.size()]);
+        Thread[] threads = threadSet.toArray(new Thread[0]);
         Arrays.sort(threads, new Comparator<Thread>() {
             public int compare(@NonNull Thread lhs, @NonNull Thread rhs) {
                 return Long.valueOf(lhs.getId()).compareTo(rhs.getId());