Refactoring to prepare for getting #4300 merged

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/databind/deser/impl/JDKValueInstantiators.java

@@ -51,22 +51,36 @@ public static ValueInstantiator findStdValueInstantiator(DeserializationConfig c
         return null;
     }
 
-    private static class ArrayListInstantiator
+    private abstract static class JDKValueInstantiator
         extends ValueInstantiator.Base
         implements java.io.Serializable
     {
-        private static final long serialVersionUID = 2L;
+        private static final long serialVersionUID = 2L;    
 
-        public final static ArrayListInstantiator INSTANCE = new ArrayListInstantiator();
-        public ArrayListInstantiator() {
-            super(ArrayList.class);
+        public JDKValueInstantiator(Class<?> type) {
+            super(type);
         }
 
         @Override
-        public boolean canInstantiate() { return true; }
+        public final boolean canInstantiate() { return true; }
 
         @Override
-        public boolean canCreateUsingDefault() {  return true; }
+        public final boolean canCreateUsingDefault() {  return true; }
+
+        // Make abstract to force (re)implementation
+        @Override
+        public abstract Object createUsingDefault(DeserializationContext ctxt) throws IOException;
+    }
+
+    private static class ArrayListInstantiator
+        extends JDKValueInstantiator
+    {
+        private static final long serialVersionUID = 2L;
+
+        public final static ArrayListInstantiator INSTANCE = new ArrayListInstantiator();
+        public ArrayListInstantiator() {
+            super(ArrayList.class);
+        }
 
         @Override
         public Object createUsingDefault(DeserializationContext ctxt) throws IOException {
@@ -75,8 +89,7 @@ public Object createUsingDefault(DeserializationContext ctxt) throws IOException
     }
 
     private static class HashMapInstantiator
-        extends ValueInstantiator.Base
-        implements java.io.Serializable
+        extends JDKValueInstantiator
     {
         private static final long serialVersionUID = 2L;
 
@@ -86,21 +99,14 @@ public HashMapInstantiator() {
             super(HashMap.class);
         }
 
-        @Override
-        public boolean canInstantiate() { return true; }
-
-        @Override
-        public boolean canCreateUsingDefault() {  return true; }
-
         @Override
         public Object createUsingDefault(DeserializationContext ctxt) throws IOException {
             return new HashMap<>();
         }
     }
 
     private static class LinkedHashMapInstantiator
-        extends ValueInstantiator.Base
-        implements java.io.Serializable
+        extends JDKValueInstantiator
     {
         private static final long serialVersionUID = 2L;
 
@@ -110,21 +116,14 @@ public LinkedHashMapInstantiator() {
             super(LinkedHashMap.class);
         }
 
-        @Override
-        public boolean canInstantiate() { return true; }
-
-        @Override
-        public boolean canCreateUsingDefault() {  return true; }
-
         @Override
         public Object createUsingDefault(DeserializationContext ctxt) throws IOException {
             return new LinkedHashMap<>();
         }
     }
 
     private static class ConstantValueInstantiator
-        extends ValueInstantiator.Base
-        implements java.io.Serializable
+        extends JDKValueInstantiator
     {
         private static final long serialVersionUID = 2L;
 
@@ -135,16 +134,9 @@ public ConstantValueInstantiator(Object value) {
             _value = value;
         }
 
-        @Override // yes, since default ctor works
-        public boolean canInstantiate() { return true; }
-
-        @Override
-        public boolean canCreateUsingDefault() {  return true; }
-
         @Override
         public Object createUsingDefault(DeserializationContext ctxt) throws IOException {
             return _value;
         }
     }
-
 }