Merge branch '49-spotbugs-issues' into 'dev'

Fix some SpotBugs issues

See merge request objectbox/objectbox-java!65

Author: greenrobot

objectbox-java/src/main/java/io/objectbox/BoxStore.java

@@ -60,8 +60,8 @@
 public class BoxStore implements Closeable {
 
     /** On Android used for native library loading. */
-    @Nullable public static Object context;
-    @Nullable public static Object relinker;
+    @Nullable private static Object context;
+    @Nullable private static Object relinker;
 
     /** Change so ReLinker will update native library when using workaround loading. */
     public static final String JNI_VERSION = "2.6.0-RC";
@@ -73,6 +73,18 @@ public class BoxStore implements Closeable {
     private static final Set<String> openFiles = new HashSet<>();
     private static volatile Thread openFilesCheckerThread;
 
+    @Nullable
+    @Internal
+    public static synchronized Object getContext() {
+        return context;
+    }
+
+    @Nullable
+    @Internal
+    public static synchronized Object getRelinker() {
+        return relinker;
+    }
+
     /**
      * Convenience singleton instance which gets set up using {@link BoxStoreBuilder#buildDefault()}.
      * <p>
@@ -276,16 +288,19 @@ static boolean isFileOpen(final String canonicalPath) {
         synchronized (openFiles) {
             if (!openFiles.contains(canonicalPath)) return false;
         }
-        if (openFilesCheckerThread == null || !openFilesCheckerThread.isAlive()) {
+        Thread checkerThread = BoxStore.openFilesCheckerThread;
+        if (checkerThread == null || !checkerThread.isAlive()) {
             // Use a thread to avoid finalizers that block us
-            openFilesCheckerThread = new Thread(() -> {
+            checkerThread = new Thread(() -> {
                 isFileOpenSync(canonicalPath, true);
-                openFilesCheckerThread = null; // Clean ref to itself
+                BoxStore.openFilesCheckerThread = null; // Clean ref to itself
             });
-            openFilesCheckerThread.setDaemon(true);
-            openFilesCheckerThread.start();
+            checkerThread.setDaemon(true);
+
+            BoxStore.openFilesCheckerThread = checkerThread;
+            checkerThread.start();
             try {
-                openFilesCheckerThread.join(500);
+                checkerThread.join(500);
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }

objectbox-java/src/main/java/io/objectbox/BoxStoreBuilder.java

@@ -27,6 +27,7 @@
 import java.io.OutputStream;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 import javax.annotation.Nonnull;
@@ -107,10 +108,11 @@ private BoxStoreBuilder() {
     /** Called internally from the generated class "MyObjectBox". Check MyObjectBox.builder() to get an instance. */
     @Internal
     public BoxStoreBuilder(byte[] model) {
-        this.model = model;
         if (model == null) {
             throw new IllegalArgumentException("Model may not be null");
         }
+        // Future-proofing: copy to prevent external modification.
+        this.model = Arrays.copyOf(model, model.length);
     }
 
     /**

objectbox-java/src/main/java/io/objectbox/internal/NativeLibraryLoader.java

@@ -181,22 +181,22 @@ private static void checkUnpackLib(String filename) {
     }
 
     private static boolean loadLibraryAndroid() {
-        if (BoxStore.context == null) {
+        if (BoxStore.getContext() == null) {
             return false;
         }
 
         //noinspection TryWithIdenticalCatches
         try {
             Class<?> context = Class.forName("android.content.Context");
-            if (BoxStore.relinker == null) {
+            if (BoxStore.getRelinker() == null) {
                 // use default ReLinker
                 Class<?> relinker = Class.forName("com.getkeepsafe.relinker.ReLinker");
                 Method loadLibrary = relinker.getMethod("loadLibrary", context, String.class, String.class);
-                loadLibrary.invoke(null, BoxStore.context, OBJECTBOX_JNI, BoxStore.JNI_VERSION);
+                loadLibrary.invoke(null, BoxStore.getContext(), OBJECTBOX_JNI, BoxStore.JNI_VERSION);
             } else {
                 // use custom ReLinkerInstance
-                Method loadLibrary = BoxStore.relinker.getClass().getMethod("loadLibrary", context, String.class, String.class);
-                loadLibrary.invoke(BoxStore.relinker, BoxStore.context, OBJECTBOX_JNI, BoxStore.JNI_VERSION);
+                Method loadLibrary = BoxStore.getRelinker().getClass().getMethod("loadLibrary", context, String.class, String.class);
+                loadLibrary.invoke(BoxStore.getRelinker(), BoxStore.getContext(), OBJECTBOX_JNI, BoxStore.JNI_VERSION);
             }
         } catch (NoSuchMethodException e) {
             return false;

objectbox-java/src/main/java/io/objectbox/model/EntityFlags.java

@@ -28,7 +28,8 @@ private EntityFlags() { }
    */
   public static final int USE_NO_ARG_CONSTRUCTOR = 1;
 
-  public static final String[] names = { "USE_NO_ARG_CONSTRUCTOR", };
+  // Private to protect contents from getting modified.
+  private static final String[] names = { "USE_NO_ARG_CONSTRUCTOR", };
 
   public static String name(int e) { return names[e - USE_NO_ARG_CONSTRUCTOR]; }
 }

objectbox-java/src/main/java/io/objectbox/model/PropertyType.java

@@ -69,7 +69,8 @@ private PropertyType() { }
   public static final short DateVector = 31;
   public static final short DateNanoVector = 32;
 
-  public static final String[] names = { "Unknown", "Bool", "Byte", "Short", "Char", "Int", "Long", "Float", "Double", "String", "Date", "Relation", "DateNano", "Reserved2", "Reserved3", "Reserved4", "Reserved5", "Reserved6", "Reserved7", "Reserved8", "Reserved9", "Reserved10", "BoolVector", "ByteVector", "ShortVector", "CharVector", "IntVector", "LongVector", "FloatVector", "DoubleVector", "StringVector", "DateVector", "DateNanoVector", };
+  // Private to protect contents from getting modified.
+  private static final String[] names = { "Unknown", "Bool", "Byte", "Short", "Char", "Int", "Long", "Float", "Double", "String", "Date", "Relation", "DateNano", "Reserved2", "Reserved3", "Reserved4", "Reserved5", "Reserved6", "Reserved7", "Reserved8", "Reserved9", "Reserved10", "BoolVector", "ByteVector", "ShortVector", "CharVector", "IntVector", "LongVector", "FloatVector", "DoubleVector", "StringVector", "DateVector", "DateNanoVector", };
 
   public static String name(int e) { return names[e]; }
 }

objectbox-java/src/main/java/io/objectbox/query/OrderFlags.java

@@ -46,7 +46,8 @@ private OrderFlags() { }
    */
   public static final int NULLS_ZERO = 16;
 
-  public static final String[] names = { "DESCENDING", "CASE_SENSITIVE", "", "UNSIGNED", "", "", "", "NULLS_LAST", "", "", "", "", "", "", "", "NULLS_ZERO", };
+  // Private to protect contents from getting modified.
+  private static final String[] names = { "DESCENDING", "CASE_SENSITIVE", "", "UNSIGNED", "", "", "", "NULLS_LAST", "", "", "", "", "", "", "", "NULLS_ZERO", };
 
   public static String name(int e) { return names[e - DESCENDING]; }
 }

objectbox-java/src/main/java/io/objectbox/relation/ToMany.java

@@ -68,14 +68,14 @@ public class ToMany<TARGET> implements List<TARGET>, Serializable {
     private final Object entity;
     private final RelationInfo<Object, TARGET> relationInfo;
 
-    private ListFactory listFactory;
+    private volatile ListFactory listFactory;
     private List<TARGET> entities;
 
     /** Counts of all entities in the list ({@link #entities}). */
     private Map<TARGET, Integer> entityCounts;
 
     /** Entities added since last put/sync. Map is used as a set (value is always Boolean.TRUE). */
-    private Map<TARGET, Boolean> entitiesAdded;
+    private volatile Map<TARGET, Boolean> entitiesAdded;
 
     /** Entities removed since last put/sync. Map is used as a set (value is always Boolean.TRUE). */
     private Map<TARGET, Boolean> entitiesRemoved;
@@ -129,14 +129,16 @@ public synchronized void setRemoveFromTargetBox(boolean removeFromTargetBox) {
     }
 
     public ListFactory getListFactory() {
-        if (listFactory == null) {
+        ListFactory result = listFactory;
+        if (result == null) {
             synchronized (this) {
-                if (listFactory == null) {
-                    listFactory = new CopyOnWriteArrayListFactory();
+                result = listFactory;
+                if (result == null) {
+                    listFactory = result = new CopyOnWriteArrayListFactory();
                 }
             }
         }
-        return listFactory;
+        return result;
     }
 
     private void ensureBoxes() {