Skip to content
This repository


Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP

A generic compact Trie implementation in Java. Built for high-performance applications.

branch: master

Fetching latest commit…

Cannot retrieve the latest commit at this time



A generic Trie implementation in Java. TrieHard comes ready to create Tries of many types:
String, char[], byte[], int[], short[], long[], and java.nio.ByteBuffer

Code Example

Trie<String, Boolean> t = Tries.forStrings();

// Include
t.put( "java.lang.", true );
t.put( "", true );
t.put( "java.util.concurrent.", true );

// Exclude
t.put( "java.util.", false );
t.put( "java.lang.Boolean", false );

assertTrue( t.get( "java.lang.Integer" ) );
assertTrue( t.get( "java.lang.Long" ) );
assertFalse( t.get( "java.lang.Boolean" ) );
assertTrue( t.get( "" ) );
assertFalse( t.get( "java.util.ArrayList" ) );
assertTrue( t.get( "java.util.concurrent.ConcurrentHashMap" ) );


You can insert millions of keys/values into TrieHard in a second (average insert on all dictionary words is 300-400 nanoseconds) as well as retrieve millions of values in a second (average retrieval is 200-300 nanoseconds).

How does it work compared to other Tries?

A typical Trie implementation has an element (i.e. character) per node (a non-compact structure). The Trie implementation in this library is a compact Trie which saves space and is just as efficient.

What are the matching options and how do they work?

Given a Trie { "" => 23 }...

  1. EXACT
    Only an equivalent "" will result in 23.
    Any superset or equivalent of "" will result in 23. I.E. "" is a STARTS_WITH match to the Trie.
    Any subset, superset, or equivalent of "" will result in 23. I.E. "java" is a PARTIAL match to the Trie.


Use Cases


Trie<String, Integer> t = Tries.forInsensitiveStrings();
t.setDefaultMatch( TrieMatch.PARTIAL );
// Add all available values to the Trie
t.put( "world", 23 );
t.put( "worm", 45 );
t.put( "worry", 76 );
t.put( "why", -89 );
t.put( "women", 123 );
// Given user input, what are possible keys & values?
String userInput = "WO";
Set<Entry<String, Integer>> possible = t.nodes( userInput );
// possible = { world=>23, worm=>45, worry=>76, women=>123 }
// Use possible to display full keys and their values.

IP to Host Mapping

Trie<byte[], String> mapper = Tries.forBytes();
mapper.setDefaultMatch( TrieMatch.EXACT );
mapper.put( socketAddress.getAddress(), "" );

// Given an IP, get the host name
String host = mapper.get( socketAddress.getAddress() );

To see other use cases, request one!

How do I create my own Trie type?

Implement the following interface and pass it into the constructor of Trie.

public interface TrieSequencer<S> 
   public int matches(S sequenceA, int indexA, S sequenceB, int indexB, int count);
   public int lengthOf(S sequence);
   public int hashOf(S sequence, int index);
Something went wrong with that request. Please try again.