Graph Theory convert python to java

I need a python script converted to a java program. Completed program should be able to take an adjacency list and classify edges as follows: 1. If w is undiscovered at the time vw is explored, then vw is called a tree edge, and v becomes the parent of w. 2. If w is an ancestor of v, then vw is called a back edge. (This includes vv.) 3. If w is a descendant of v, but w has been discovered earlier than the time vw is explored, then vw is called a descendant edge (other names are forward edge and frond). 4. If w has no ancestor/descendant relationship to v, then vw is called a cross edge. The python code and description are attached.