isCOBOL Evolve : Language Reference : Object-oriented Programming : Object management
Object management
As mentioned previously, objects are allocated at runtime and are accessed only through object references. An object is created by invoking a method in a factory object. The object continues to exist until it can no longer be accessed. The object can no longer be accessed when no object reference data item references that object.
Example 1
The following code creates two String objects, displays their length and deallocates them.
       CONFIGURATION SECTION.
       REPOSITORY.
           CLASS JSTRING AS "java.lang.String"
           CLASS JSYSTEM AS "java.lang.System"
           .
 
       WORKING-STORAGE SECTION.
       77 STR1 OBJECT REFERENCE JSTRING.
       77 STR2 OBJECT REFERENCE JSTRING.
       77 STR3 OBJECT REFERENCE JSTRING.
 
       PROCEDURE DIVISION.
       MAIN.
      * allocate String object from factory method
           SET STR1 TO JSYSTEM:>getProperty ( "user.dir" )
      * allocate String object by instantiating it
           SET STR2 TO JSTRING:>new("Some text").
      * allocate String object through autoboxing
           SET STR3 TO "A string".
      * use the lenght() method of the String objects
           DISPLAY STR1:>length().
           DISPLAY STR2:>length().
           DISPLAY STR3:>length().
      * deallocate the String ojbects and exit
           SET STR1 TO NULL.
           SET STR2 TO NULL.
           SET STR2 TO NULL.
           GOBACK.
Example 2
This is a shorter form of the above example, where objects are implicitly allocated through their Working-Storage definition, allowing you to save Procedure Division code.
       CONFIGURATION SECTION.
       REPOSITORY.
           CLASS JSTRING AS "java.lang.String"
           CLASS JSYSTEM AS "java.lang.System"
           .
 
       WORKING-STORAGE SECTION.
       77 STR1 OBJECT REFERENCE JSTRING VALUE JSYSTEM:>getProperty ( "user.dir" ).
       77 STR2 OBJECT REFERENCE JSTRING VALUE JSTRING:>new("Some text").
       77 STR3 OBJECT REFERENCE JSTRING VALUE "A string".
 
       PROCEDURE DIVISION.
       MAIN.
      * use the lenght() method of the String objects
           DISPLAY STR1:>length().
           DISPLAY STR2:>length().
           DISPLAY STR3:>length().
      * deallocate the String ojbects and exit
           SET STR1 TO NULL.
           SET STR2 TO NULL.
           SET STR3 TO NULL.
           GOBACK.