I have been looking everywhere for information on HashMaps,
particularly how to put one hash map into another HashMap.
This is where the expression RTFM (Read That Fine Manual) comes to
mind. Although notorious for being extremely sparse in certain
sections, the javadoc API documentation that comes with the Java 2
Platform SDKs is extremely helpful in describing the use of the
HashMap class. I cannot overstate how useful it is to have a Web
browser opened to the API docs at all times when writing Java
In short, HashMap is a reimplementation of the Hashtable class to work
with the Java 2 Collections Framework. Unlike Hashtable, none of its
methods are synchronized. A HashMap associates a value with an
arbitrary key. These associations are created with the
put(Object key, Object value) method. An association can
be removed with
remove(Object key). Any object can be stored as a value , including a HashMap. To store one HashMap into
another, simply use it as the value argument to put().