Getting TLE in PT07Z spoj(Longest path in a tree) in java. Please help

problem link: http://www.spoj.com/problems/PT07Z/

I have used both double BFS and double DFS for this but getting TLE for both approaches while these two approaches worked for C/C++ users. What can I do to optimize my code? What else is required to get it accepted? These are my two Solutions:

1) DFS approach: http://ideone.com/sIrQsD
2) BFS approach: http://ideone.com/7nHEcA