John Russell's "Frequency Counting"
If you do not have java compiler on your computer, install Java on your computer via www.java.com. Then, create a java language program that performs a frequency counting. You can see how to compile a java code via the java tutorials provided here. One possible solution can be found via the link above, under the Frequency Counting section. Study the solution code only after you have solved the problem or spent a substantial amount of time working on it.
Click https://s3.amazonaws.com/saylordotorg-resources/wwwresources/site/wp-content/uploads/2012/07/Cryptology-Programs.pdf link to open resource.