Refactor to make more fields final

src/main/java/com/networknt/schema/BaseJsonValidator.java

@@ -20,6 +20,7 @@
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import com.networknt.schema.annotation.JsonNodeAnnotation;
 import com.networknt.schema.i18n.DefaultMessageSource;
+import com.networknt.schema.i18n.MessageSource;
 
 import org.slf4j.Logger;
 
@@ -29,12 +30,15 @@
 import java.util.Set;
 import java.util.function.Consumer;
 
+/**
+ * Base {@link JsonValidator}. 
+ */
 public abstract class BaseJsonValidator extends ValidationMessageHandler implements JsonValidator {
     protected final boolean suppressSubSchemaRetrieval;
 
     protected final JsonNode schemaNode;
 
-    protected ValidationContext validationContext;
+    protected final ValidationContext validationContext;
 
     public BaseJsonValidator(SchemaLocation schemaLocation, JsonNodePath evaluationPath, JsonNode schemaNode,
             JsonSchema parentSchema, ValidatorTypeCode validatorType, ValidationContext validationContext) {
@@ -60,15 +64,41 @@ public BaseJsonValidator(SchemaLocation schemaLocation, JsonNodePath evaluationP
     }
 
     /**
-     * Copy constructor.
-     * 
-     * @param copy to copy from
+     * Constructor to create a copy using fields.
+     *
+     * @param suppressSubSchemaRetrieval to suppress sub schema retrieval
+     * @param schemaNode the schema node
+     * @param validationContext the validation context
+     * @param errorMessageType the error message type
+     * @param customErrorMessagesEnabled whether custom error msessages are enabled
+     * @param messageSource the message source
+     * @param keyword the keyword
+     * @param parentSchema the parent schema
+     * @param schemaLocation the schema location
+     * @param evaluationPath the evaluation path
+     * @param evaluationParentSchema the evaluation parent schema
+     * @param errorMessage the error message
      */
-    protected BaseJsonValidator(BaseJsonValidator copy) {
-        super(copy);
-        this.suppressSubSchemaRetrieval = copy.suppressSubSchemaRetrieval;
-        this.schemaNode = copy.schemaNode;
-        this.validationContext = copy.validationContext;
+    protected BaseJsonValidator(
+            /* Below from BaseJsonValidator */
+            boolean suppressSubSchemaRetrieval,
+            JsonNode schemaNode,
+            ValidationContext validationContext,
+            /* Below from ValidationMessageHandler */
+            ErrorMessageType errorMessageType,
+            boolean customErrorMessagesEnabled,
+            MessageSource messageSource,
+            Keyword keyword,
+            JsonSchema parentSchema,
+            SchemaLocation schemaLocation,
+            JsonNodePath evaluationPath,
+            JsonSchema evaluationParentSchema,
+            Map<String, String> errorMessage) {
+        super(errorMessageType, customErrorMessagesEnabled, messageSource, keyword,
+                parentSchema, schemaLocation, evaluationPath, evaluationParentSchema, errorMessage);
+        this.suppressSubSchemaRetrieval = suppressSubSchemaRetrieval;
+        this.schemaNode = schemaNode;
+        this.validationContext = validationContext;
     }
 
     private static JsonSchema obtainSubSchemaNode(final JsonNode schemaNode, final ValidationContext validationContext) {

src/main/java/com/networknt/schema/CollectorContext.java

@@ -28,16 +28,35 @@ public class CollectorContext {
     /**
      * Map for holding the name and {@link Collector} or a simple Object.
      */
-    private Map<String, Object> collectorMap = new HashMap<>();
+    private final Map<String, Object> collectorMap;
 
     /**
      * Map for holding the name and {@link Collector} class collect method output.
      */
-    private Map<String, Object> collectorLoadMap = new HashMap<>();
+    private final Map<String, Object> collectorLoadMap;
 
+    /**
+     * Default constructor will use an unsynchronized HashMap to store data. This is
+     * suitable if the collector context is not shared with multiple threads.
+     */
     public CollectorContext() {
+        this(new HashMap<>(), new HashMap<>());
     }
 
+    /**
+     * Constructor that creates the context using the specified instances to store
+     * data.
+     * <p>
+     * If for instance the collector context needs to be shared with multiple
+     * threads a ConcurrentHashMap can be used.
+     *
+     * @param collectorMap the collector map
+     * @param collectorLoadMap the collector load map
+     */
+    public CollectorContext(Map<String, Object> collectorMap, Map<String, Object> collectorLoadMap) {
+        this.collectorMap = collectorMap;
+        this.collectorLoadMap = collectorLoadMap;
+    }
 
     /**
      * Adds a collector with give name. Preserving this method for backward

src/main/java/com/networknt/schema/ContainsValidator.java

@@ -42,9 +42,9 @@ public class ContainsValidator extends BaseJsonValidator {
     private final JsonSchema schema;
     private final boolean isMinV201909;
 
-    private Integer min = null;
-    private Integer max = null;
-    
+    private final Integer min;
+    private final Integer max;
+
     private Boolean hasUnevaluatedItemsValidator = null;
 
     public ContainsValidator(SchemaLocation schemaLocation, JsonNodePath evaluationPath, JsonNode schemaNode, JsonSchema parentSchema, ValidationContext validationContext) {
@@ -55,19 +55,29 @@ public ContainsValidator(SchemaLocation schemaLocation, JsonNodePath evaluationP
         // slightly.
         this.isMinV201909 = MinV201909.getVersions().contains(this.validationContext.getMetaSchema().getSpecification());
 
+        Integer currentMax = null;
+        Integer currentMin = null;
         if (schemaNode.isObject() || schemaNode.isBoolean()) {
             this.schema = validationContext.newSchema(schemaLocation, evaluationPath, schemaNode, parentSchema);
             JsonNode parentSchemaNode = parentSchema.getSchemaNode();
-            Optional.ofNullable(parentSchemaNode.get(ValidatorTypeCode.MAX_CONTAINS.getValue()))
-                    .filter(JsonNode::canConvertToExactIntegral)
-                    .ifPresent(node -> this.max = node.intValue());
+            Optional<JsonNode> maxNode = Optional
+                    .ofNullable(parentSchemaNode.get(ValidatorTypeCode.MAX_CONTAINS.getValue()))
+                    .filter(JsonNode::canConvertToExactIntegral);
+            if (maxNode.isPresent()) {
+                currentMax = maxNode.get().intValue();
+            }
 
-            Optional.ofNullable(parentSchemaNode.get(ValidatorTypeCode.MIN_CONTAINS.getValue()))
-                    .filter(JsonNode::canConvertToExactIntegral)
-                    .ifPresent(node -> this.min = node.intValue());
+            Optional<JsonNode> minNode = Optional
+                    .ofNullable(parentSchemaNode.get(ValidatorTypeCode.MIN_CONTAINS.getValue()))
+                    .filter(JsonNode::canConvertToExactIntegral);
+            if (minNode.isPresent()) {
+                currentMin = minNode.get().intValue();
+            }
         } else {
             this.schema = null;
         }
+        this.max = currentMax;
+        this.min = currentMin;
     }
 
     @Override

src/main/java/com/networknt/schema/ContentEncodingValidator.java

@@ -32,7 +32,7 @@
  */
 public class ContentEncodingValidator extends BaseJsonValidator {
     private static final Logger logger = LoggerFactory.getLogger(ContentEncodingValidator.class);
-    private String contentEncoding;
+    private final String contentEncoding;
 
     /**
      * Constructor.