Colt HashMap

Extension of Colt HashMap using Generics for storage of Objects

This is based on part of the code from Colt Project: http://acs.lbl.gov/software/colt/ The Colt Project is made before generics was introduced in Java. This means that the HashMap from Colt Project cannot be used as a drop-in replacement for Java's HashMap.

This version contains only the HashMap part of Colt Project (version 1.2.0) and adds the support for generics, so that it can now be used as a drop-in replacement for Java's HashHamp

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Changes to original code

• Removed all non-hashmap relevant code
• Fixed bug where OpenLongObjectHashMap.indexOfValue(...) and OpenIntObjectHashMap.indexOfValue(...) used "==" rather than equals for Object types.
• Created new interfaces and classes for wrapping Colt Project HashMap in Java's Map<K,V> interface.

Usage

Class	Key type	Value type
ColtIntHashMap	Int	Object
ColtIntIntHashMap	Int	Int
ColtQuickIntIntHashMap	Int	Int
ColtIntDoubleHashMap	Int	Double
ColtLongHashMap	Long	Object
ColtDoubleIntHashMap	Double	Int

Existing code can easily be changed to use new HashMaps's.

//From
Map<Integer, String> map = new HashMap<Integer,String>();
map.put(3,"test");

//To
Map<Integer, String> map = new ColtIntHashMap<String>();
map.put(3,"test");

//For maximum performance, its necessary to use the original type when putting and retrieving from the map.
Map<Integer, String> map = new ColtIntHashMap<String>();
((ColtIntHashMap<String>)map).put(3,"test");

Benchmark

JVM options: -Xms8g -Xmx8g Insertions: 20 million Removals: 6 million Contains key: 4 million

Benchmark of Integer,Object

JVM 1.6

Map	Memory usage (mb)	Insertion time (sec.)
Java HashMap
Colt HashMap
Colt (Native) HashMap
Colt (IntInt) HashMap
Colt (Quick IntInt) HashMap

JVM 1.7