CS151 Object Oriented Programming

Homework 4

Cool JNI Exercise

This exercise is going to give students exposure to Java Native Interface (JNI) concept. You are required to write two programs.

C++ Program

Write a C++ program named dosCommand.cpp using MSVC++ that does the following:

• This C++ program is going to be called from the Java Program
• The program is going to take "one" real parameter. The parameter is the command to be executed in MS-DOS. (For example, dir, help, ver)
• The program is going to execute the inputted command.
• Output of the command is going to be captured within the C++ program in an array of characters (1D array or 2D array, any data structure, your choice)
• A method from the Java program will be called to pass the output back to the Java program.

Java Program

Write a Java program named j2dosDriver.java using JDK 1.3 that does the following:

• The program is going to take one parameter (the MS-DOS command to be executed)
• This Java program is going to call a native C++ program (docCommand.cpp)
• It is going to pass the inputted  MS-DOS command String to the C++ program
• It expects a data structure with the command output will be passed back from the C++ program
• In the Java program, it is going to print out the output passed back from the C++ program

Extra Credit

Extra credit is built in in the program. In order to do this homework, you have to research how JNI program is built, how to use javah, how to build DLL in Windows, how to map Java types. to C++ types. While most of the concepts will be covered later in the class, it is essential you do your research as needed. (If you wait for the lectures, it is going to be too late.) Good Luck :)

NOTE: What to handin:

• Use a good word processor to writeup all the written assignments. Print them out and handin in class.
• Handin DETAIL running instructions and the actual program (source + class files + html file, etc). Print instruction and program listing out, and hand them in with the computer diskette.
• No late assignment will be accepted
• DO NOT EMAIL ANY assignment to me. Handin in class
• Points will be taken off if you violate any of the above.