Access COBOL variables within Embedded Java

You can embed Java source within your COBOL program with the EXEC JAVA ... END-EXEC statement.  Java source is generated at the point in which it appears within the program.

Reference COBOL variables with the ::element-or-group-name:: designator.  If used on the right side of an assignment statement or within a method call, this designator will generate accessor method invocations (getters) for the various types. For example, if the element is defined as a PIC X(10) the designator will replaced by an accessor that returns a String value for the element.  An element defined as a PIC 9(9) COMP would produce an int value.  For example,

EXEC JAVA
    String a = ::WS-PICX10::;
    System.out.println("value: " + a);
END-EXEC

You can invoke mutilator  methods (setters) by placing a "." and method name and parameters after the designator.  For example,

EXEC JAVA
    ::WS-DATE::.move((new Date()).toString());
END-EXEC

All of the Variable class accessors and mutilators that are part of the ICobol interrface are available to use.  Here are some examples,

Your Java should be fairly simple, prefering to invoke other pure Java class methods you define within the java_source folder of your COBOL project.  To import these methods into the generated Java source, or other classes, use the compiler directive -out:importjava followed by a class specification.  One ore more of these directives can be provided.  These can be included in the source file with the $SET DIRECTIVE statement.

Here's a complete example:

     $SET DIRECTIVE(-out:importjava org.json.*) 
      IDENTIFICATION DIVISION. 
      PROGRAM-ID. json2cobol. 
     *
     * how to use JSON in Elastic COBOL
     *
      WORKING-STORAGE SECTION.
         01 WS-PAGENAME            PIC X(20)  VALUE SPACES.
         01 PARM-DATA              PIC X(100) VALUE SPACES.
      PROCEDURE DIVISION. 
           move '{"pageInfo": {"pageName": "abc","pagePic": "http://exa      - 
            'mple.com/content.jpg"}}' to parm-data 
           display 'JSON to Parse:' parm-data upon sysout.
           exec java
               JSONObject obj = new JSONObject(::PARM-DATA::);
               JSONObject pageInfoObj = obj.getJSONObject("pageInfo"); 
               String pageName = pageInfoObj.getString("pageName");
               ::WS-PAGENAME::.move(pageName);
           end-exec.
           display 'Parsed JSON page name: ' WS-PAGENAME upon sysout.
      end program json2cobol.

Compile and run program with the -cp flag to indicate where to find the JSON jar files (CLASSPATH contains ecobol.jar)

ecobol -cp $CLASSPATH:json.jar json2cobol.cbl

java -cp $CLASSPATH:json.jar json2cobol