Package com.cedarsoftware.util

Class ConcurrentHashMapNullSafe<K,V>

java.lang.Object
com.cedarsoftware.util.AbstractConcurrentNullSafeMap<K,V>
com.cedarsoftware.util.ConcurrentHashMapNullSafe<K,V>
Type Parameters:
K - the type of keys maintained by this map
V - the type of mapped values
All Implemented Interfaces:
ConcurrentMap<K,V>, Map<K,V>
public class ConcurrentHashMapNullSafe<K,V> extends AbstractConcurrentNullSafeMap<K,V>
A thread-safe implementation of ConcurrentMap that supports null keys and null values by using internal sentinel objects.

ConcurrentHashMapNullSafe extends AbstractConcurrentNullSafeMap and uses a ConcurrentHashMap as its backing implementation. This class retains all the advantages of ConcurrentHashMap (e.g., high concurrency, thread safety, and performance) while enabling safe handling of null keys and values.

Key Features

  • Thread-safe and highly concurrent.
  • Supports null keys and null values through internal sentinel objects.
  • Adheres to the Map and ConcurrentMap contracts.
  • Provides multiple constructors to control initial capacity, load factor, and populate from another map.

Usage Example


 // Create an empty ConcurrentHashMapNullSafe
 ConcurrentHashMapNullSafe<String, String> map = new ConcurrentHashMapNullSafe<>();
 map.put(null, "nullKey");
 map.put("key", null);

 // Populate from another map
 Map<String, String> existingMap = Map.of("a", "b", "c", "d");
 ConcurrentHashMapNullSafe<String, String> populatedMap = new ConcurrentHashMapNullSafe<>(existingMap);

 System.out.println(map.get(null));  // Outputs: nullKey
 System.out.println(map.get("key")); // Outputs: null
 System.out.println(populatedMap);  // Outputs: {a=b, c=d}
Author:
John DeRegnaucourt
Copyright (c) Cedar Software LLC

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

License

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
See Also:

  • Constructor Details

    • ConcurrentHashMapNullSafe

      public ConcurrentHashMapNullSafe()
      Constructs a new, empty ConcurrentHashMapNullSafe with the default initial capacity (16) and load factor (0.75).

      This constructor creates a thread-safe map suitable for general-purpose use, retaining the concurrency properties of ConcurrentHashMap while supporting null keys and values.

    • ConcurrentHashMapNullSafe

      public ConcurrentHashMapNullSafe(int initialCapacity)
      Constructs a new, empty ConcurrentHashMapNullSafe with the specified initial capacity and default load factor (0.75).
      Parameters:
      initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements.
      Throws:
      IllegalArgumentException - if the initial capacity is negative

    • ConcurrentHashMapNullSafe

      public ConcurrentHashMapNullSafe(int initialCapacity, float loadFactor)
      Constructs a new, empty ConcurrentHashMapNullSafe with the specified initial capacity and load factor.
      Parameters:
      initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements.
      loadFactor - the load factor threshold, used to control resizing. Resizing may be performed when the average number of elements per bin exceeds this threshold.
      Throws:
      IllegalArgumentException - if the initial capacity is negative or the load factor is nonpositive

    • ConcurrentHashMapNullSafe

      public ConcurrentHashMapNullSafe(Map<? extends K,? extends V> m)
      Constructs a new ConcurrentHashMapNullSafe with the same mappings as the specified map.

      This constructor copies all mappings from the given map into the new ConcurrentHashMapNullSafe. The mappings are inserted in the order returned by the source map's entrySet iterator.

      Parameters:
      m - the map whose mappings are to be placed in this map
      Throws:
      NullPointerException - if the specified map is null