To build:
    This example uses a public domain version of the ConcurrentHashMap
    that provides for weak (and other types of) references. That source
    is included; see src/extra166y/CustomConcurrentHashMap.java for
    license details.

To run:
    java  -jar jars/stringintern.jar self|jdk
    jdk -- use the standard string intern call in the jdk (tested with
           various StringTableSize arguments)
    self -- use a custom cannonical string representation