Source code plagiarism is a very serious problem in academia. Lot of assignment work in programming courses is submitted electronically by the students. This makes it difficult for the faculty to check each and every code separately. Using a plagiarism detection tool makes it easy to check and analyze student’s assignment. In programming courses, students submit their work in form of java source code files. There is a possibility that students may copy the Java code files from another source without properly crediting the original writer or programmer, intentionally or unintentionally. This is also a form of plagiarism. The main purpose of this paper is to show a method to detect plagiarism in java source code. To do this first it makes all the submitted java codes into a similar pattern by removing comments. Then tokenization is done. Finally the tokens are compared to get the similar portions and are displayed accordingly.