Corrected PMD violations

.gitignore

@@ -1 +1,2 @@
 target/*
+.pmd

src/main/java/net/abhinavsarkar/spelhelper/ImplicitMethodResolver.java

@@ -30,7 +30,7 @@ import org.springframework.expression.spel.support.ReflectiveMethodResolver;
 
 final class ImplicitMethodResolver implements MethodResolver {
 
-    private static final ConcurrentHashMap<String, MethodExecutor> cache =
+    private static final ConcurrentHashMap<String, MethodExecutor> CACHE =
         new ConcurrentHashMap<String, MethodExecutor>();
 
     private static final MethodExecutor NULL_ME = new MethodExecutor() {
@@ -44,7 +44,7 @@ final class ImplicitMethodResolver implements MethodResolver {
             MethodExecutor {
         private final MethodExecutor executor;
 
-        private ImplicitMethodExecutor(final MethodExecutor executor) {
+        public ImplicitMethodExecutor(final MethodExecutor executor) {
             this.executor = executor;
         }
 
@@ -65,8 +65,8 @@ final class ImplicitMethodResolver implements MethodResolver {
         }
         Class<?> type = targetObject.getClass();
         String cacheKey = type.getName() + "." + name;
-        if (cache.containsKey(cacheKey)) {
-            MethodExecutor executor = cache.get(cacheKey);
+        if (CACHE.containsKey(cacheKey)) {
+            MethodExecutor executor = CACHE.get(cacheKey);
             return executor == NULL_ME ? null : executor;
         }
 
@@ -75,25 +75,24 @@ final class ImplicitMethodResolver implements MethodResolver {
             int modifiers = method.getModifiers();
             if (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers)) {
                 Class<?>[] parameterTypes = method.getParameterTypes();
-                Class<?> firstParameterType = parameterTypes[0];
+                Class<?> firstParamType = parameterTypes[0];
                 if (parameterTypes.length > 0
-                        && firstParameterType.isAssignableFrom(type)) {
-
-                    Class<?>[] modifiedArgumentTypes = new Class[argumentTypes.length + 1];
-                    modifiedArgumentTypes[0] = firstParameterType;
-                    System.arraycopy(argumentTypes, 0, modifiedArgumentTypes,
+                        && firstParamType.isAssignableFrom(type)) {
+                    Class<?>[] newArgumentTypes = new Class[argumentTypes.length + 1];
+                    newArgumentTypes[0] = firstParamType;
+                    System.arraycopy(argumentTypes, 0, newArgumentTypes,
                             1, argumentTypes.length);
                     MethodExecutor executor = new ReflectiveMethodResolver()
                             .resolve(context, method.getDeclaringClass(), name,
-                                    modifiedArgumentTypes);
+                                    newArgumentTypes);
                     MethodExecutor wrappedExecutor = executor == null ? null
                             : new ImplicitMethodExecutor(executor);
-                    cache.putIfAbsent(cacheKey, wrappedExecutor);
+                    CACHE.putIfAbsent(cacheKey, wrappedExecutor);
                     return wrappedExecutor;
                 }
             }
         }
-        cache.putIfAbsent(cacheKey, NULL_ME);
+        CACHE.putIfAbsent(cacheKey, NULL_ME);
         return null;
     }
 

src/main/java/net/abhinavsarkar/spelhelper/ImplicitMethods.java

@@ -33,6 +33,9 @@ import java.util.Set;
  */
 public final class ImplicitMethods {
 
+    private ImplicitMethods() {
+    }
+
     /**
      * Provides implicit method `distinct` on the {@link List} class.
      *

src/main/java/net/abhinavsarkar/spelhelper/ImplicitPropertyAccessor.java

@@ -29,7 +29,7 @@ import org.springframework.util.Assert;
 
 final class ImplicitPropertyAccessor extends ReadOnlyGenericPropertyAccessor {
 
-    private static final ConcurrentHashMap<String, MethodExecutor> cache =
+    private static final ConcurrentHashMap<String, MethodExecutor> CACHE =
         new ConcurrentHashMap<String, MethodExecutor>();
 
     public boolean canRead(final EvaluationContext context,
@@ -37,19 +37,19 @@ final class ImplicitPropertyAccessor extends ReadOnlyGenericPropertyAccessor {
             throws AccessException {
         Assert.notNull(target, "target is null");
         String cacheKey = target.getClass().getName() + "." + name;
-        if (cache.containsKey(cacheKey)) {
-            return cache.get(cacheKey) != null;
+        if (CACHE.containsKey(cacheKey)) {
+            return CACHE.get(cacheKey) != null;
         }
 
         for (MethodResolver mr : context.getMethodResolvers()) {
             MethodExecutor me = mr.resolve(context, target, name, new Class[0]);
             if (me != null) {
-                cache.putIfAbsent(cacheKey, me);
+                CACHE.putIfAbsent(cacheKey, me);
                 return true;
             }
         }
 
-        cache.putIfAbsent(cacheKey, null);
+        CACHE.putIfAbsent(cacheKey, null);
         return false;
     }
 
@@ -58,7 +58,7 @@ final class ImplicitPropertyAccessor extends ReadOnlyGenericPropertyAccessor {
             throws AccessException {
         if (canRead(context, target, name)) {
             String cacheKey = target.getClass().getName() + "." + name;
-            return cache.get(cacheKey).execute(context, target, new Object[0]);
+            return CACHE.get(cacheKey).execute(context, target, new Object[0]);
         }
         throw new AccessException(MessageFormat.format(
                 "Cannot read property: {0} of target: {1}", name, target));

src/main/java/net/abhinavsarkar/spelhelper/InheritenceUtil.java

@@ -22,39 +22,42 @@ import java.util.Set;
 
 final class InheritenceUtil {
 
-    public static Set<Class<?>> getInheritance(final Class<?> in) {
+    private InheritenceUtil() {
+    }
+
+    public static Set<Class<?>> getInheritance(final Class<?> clazz) {
         LinkedHashSet<Class<?>> result = new LinkedHashSet<Class<?>>();
-        result.add(in);
-        getInheritance(in, result);
+        result.add(clazz);
+        getInheritance(clazz, result);
         return result;
     }
 
     /**
      * Get inheritance of type.
      *
-     * @param in
+     * @param clazz
      * @param result
      */
-    private static void getInheritance(final Class<?> in, final Set<Class<?>> result) {
-        Class<?> superclass = getSuperclass(in);
+    private static void getInheritance(final Class<?> clazz, final Set<Class<?>> result) {
+        Class<?> superclass = getSuperclass(clazz);
 
         if (superclass != null) {
             result.add(superclass);
             getInheritance(superclass, result);
         }
 
-        getInterfaceInheritance(in, result);
+        getInterfaceInheritance(clazz, result);
     }
 
     /**
      * Get interfaces that the type inherits from.
      *
-     * @param in
+     * @param clazz
      * @param result
      */
-    private static void getInterfaceInheritance(final Class<?> in,
+    private static void getInterfaceInheritance(final Class<?> clazz,
             final Set<Class<?>> result) {
-        for (Class<?> c : in.getInterfaces()) {
+        for (Class<?> c : clazz.getInterfaces()) {
             result.add(c);
             getInterfaceInheritance(c, result);
         }
@@ -63,21 +66,21 @@ final class InheritenceUtil {
     /**
      * Get superclass of class.
      *
-     * @param in
+     * @param clazz
      * @return
      */
-    private static Class<?> getSuperclass(final Class<?> in) {
-        if (in == null) {
+    private static Class<?> getSuperclass(final Class<?> clazz) {
+        if (clazz == null) {
             return null;
         }
-        if (in.isArray() && in != Object[].class) {
-            Class<?> type = in.getComponentType();
+        if (clazz.isArray() && clazz != Object[].class) {
+            Class<?> type = clazz.getComponentType();
             while (type.isArray()) {
                 type = type.getComponentType();
             }
             return type;
         }
-        return in.getSuperclass();
+        return clazz.getSuperclass();
     }
 
 }

src/main/java/net/abhinavsarkar/spelhelper/SpelHelper.java

@@ -126,10 +126,10 @@ public final class SpelHelper {
     static final String CONTEXT_LOOKUP_KEY = SpelHelper.class.getName();
 
     private static final ExpressionParser PARSER = new SpelExpressionParser();
-    private static final ThreadLocal<EvaluationContext> currentContext =
+    private static final ThreadLocal<EvaluationContext> CURRENT_CONTEXT =
         new ThreadLocal<EvaluationContext>();
 
-    private volatile EvaluationContext context;
+    private EvaluationContext context;
     private final Set<Method> registeredFunctions = new HashSet<Method>();
     private final Map<String,Method> registeredMethods =
         new ConcurrentHashMap<String, Method>();
@@ -177,7 +177,9 @@ public final class SpelHelper {
      */
     public SpelHelper registerFunctionsFromClass(final Class<?> clazz) {
         registeredFunctions.addAll(filterFunctions(clazz));
-        context = null;
+        synchronized (PARSER) {
+            context = null;
+        }
         return this;
     }
 
@@ -214,9 +216,9 @@ public final class SpelHelper {
     public <T> T evalExpression(final String expressionString,
             final Object rootElement, final Class<T> desiredType) {
         EvaluationContext evaluationContext = getEvaluationContext(rootElement);
-        currentContext.set(evaluationContext);
+        CURRENT_CONTEXT.set(evaluationContext);
         T value = evalExpression(expressionString, evaluationContext, desiredType);
-        currentContext.set(null);
+        CURRENT_CONTEXT.set(null);
         return value;
     }
 
@@ -320,7 +322,7 @@ public final class SpelHelper {
      * Looks up an implicit constructor registered with this instance.
      * @param lookup    key to lookup which should be of form:
      * `constructor.getDeclaringClass().getSimpleName()`
-     *  `+ Arrays.toString(constructor.getParameterTypes())`
+     * `+ Arrays.toString(constructor.getParameterTypes())`
      * @return  The registered constructor if found, else null.
      */
     public Constructor<?> lookupImplicitConstructor(final String lookup) {
@@ -333,7 +335,7 @@ public final class SpelHelper {
      * @return  The current evaluation context.
      */
     public static EvaluationContext getCurrentContext() {
-        return currentContext.get();
+        return CURRENT_CONTEXT.get();
     }
 
     private static List<Method> filterMethods(final Class<?> clazz) {