There are two kinds of assignments in Masters of Java. One is the typical basic API knowledge like working with StringBuffers or Lists and such. The other are more focussed on analysis and design and require a good understanding of well known algorithms.

Each assignment is rated on difficulty, quality and fun. Difficulty indicates the how good a programmer you need to be to solve this assignment within half an hour. Quality indicates how good the assignment is (documentation, testset etc.). Fun finally indicates if the assignment is any Fun to do.