Comparing and setting object references

For example, code either IF statement below to check whether the object reference anAccount refers to no object instance:

If anAccount = Null . . .
If anAccount = Nulls . . .

You can code a call to IsSameObject to check whether two object references, object1 and object2, refer to the same object instance or whether each refers to no object instance. To ensure that the arguments and return value are interoperable with Java™ and to establish addressability to the callable service, code the following data definitions and statements before the call to IsSameObject:

Local-storage Section.
. . .
01  is-same Pic X.
    88 is-same-false Value X'00'.
    88 is-same-true  Value X'01' Through X'FF'.
Linkage Section.
    Copy JNI.
Procedure Division.
    Set Address Of JNIEnv To JNIEnvPtr
    Set Address Of JNINativeInterface To JNIEnv
    Call IsSameObject Using By Value JNIEnvPtr object1 object2
                      Returning is-same
    If is-same-true . . .

Within a method you can check whether an object reference refers to the object instance on which the method was invoked by coding a call to IsSameObject that compares the object reference and SELF.

You can instead invoke the Java equals method (inherited from java.lang.Object) to determine whether two object references refer to the same object instance.

You can make an object reference refer to no object instance by using the SET statement. For example:

Set anAccount To Null.

You can also make one object reference refer to the same instance as another object reference does by using the SET statement. For example:

Set anotherAccount To anAccount.

This SET statement causes anotherAccount to refer to the same object instance as anAccount does. If the receiver (anotherAccount) is a universal object reference, the sender (anAccount) can be either a universal or a typed object reference. If the receiver is a typed object reference, the sender must be a typed object reference bound to the same class as the receiver or to one of its subclasses.

Within a method you can make an object reference refer to the object instance on which the method was invoked by setting it to SELF. For example:

Set anAccount To Self.