To learn more about formatting in java check:
The purpose of tracing an algorithm is to ensure that it works. This is a paper test. Tracing involves “executing” the sequence of instructions with a sample set of values, computing by hand the value of each variable after each instruction is executed, and checking for the correct result.
See the following example: http://users.csc.calpoly.edu/~jdalbey/309/Lectures/algorithmTrace.html