Example 2: Locating the Java Property File Directly from COBOL

This example demonstrates how the JVM COBOL run-time system uses the Java property file, created using the mfjarprogmap utility, to call a program that was compiled as part of a package. It shows how you can call a .jar file containing a Java property file, directly from COBOL.

Note: The following example is designed to be run from a Visual COBOL command prompt.

Copy and paste the following code into a new file, and save it as myapp.cbl.

        program-id myapp.
        procedure division.
        display "Hello world from myapp".
        goback.
        end program myapp.

Create a trigger program to call the previous program: copy and paste the following code into a new file, and save it as caller.cbl.

        program-id caller.
        01 p procedure-pointer.
        01 runner pic x(10).
        procedure division.
        set p to entry "myapp.jar".
        move "myapp" to runner.
        call runner.
        goback.
        end program caller.

Create a sub-directory in which to compile the source, and in which the Java property file will be created.
```
mkdir bin
```
Compile the source and trigger programs.
```
cob -j caller.cbl
cob myapp.cbl -C 'jvmgen(sub)' -C 'iloutput(bin)' 
              -C 'ilnamespace(com.mycompany.desktopapp)'
```
A caller.class file is created in your current directory, and the myapp.class file is created in the bin/com/mycompany/desktopapp directory.
Create a .jar file that contains the contents of the bin directory.
```
jar cvf myapp.jar -C bin/ .
```
myapp.jar is created in the current directory.
Create the Java property file, adding it to the .jar file in the process.
```
mfjarprogmap -verbose -jar myapp.jar
```
The mfcobolprogmap.properties file is created and added to myapp.jar.
Run the trigger application.
```
java caller
```
The caller.class file runs, then calls myapp.jar, and because that .jar file contains the Java property file, the run-time system uses it to locate the called program in its packaged location. The result is that the Hello world from myapp message is displayed.