To compile the project if you are using javac as the Java compiler, head to the root folder of this project and execute the following command:
javac POSSim/*.java POSSim/simulator/*.java
To run the project (also from the root folder of the project), run the following command:
java POSSim.PostOfficeSystemSimulator
"post office system test cases 1.zip" and "post office system test cases 2.zip" have sample tester post office system source codes.