The GroundBlog By Duncan Mills
Duncan Mills's WebLog from GroundSide

It's a common issue when people are trying to call out to Java from Forms that an ORA-105101 error gets raised in Forms. This error is actually the PL/SQL exception ORA_JAVA.EXCEPTION_THROWN, and you guessed it, indicates that the Java code being called is itself throwing an exception.
As a matter of course any Java code called from Oracle Forms in this way should include the correct handlers to catch this.

1. Use the Java importer to import java.lang.Exception into the Form.
   This will create a PL/SQL package called Exception_ Note the trailing underscore which is appended because of course Exception is a PL/SQL keyword in it's own right.
2. Then wrap your calls to the imported code with the following code block
   

   declare
     raisedException ORA_JAVA.JOBJECT;
     --
     -- Your declarations here
     --
   begin
     --
     -- Your calls here
    --
   exception
     --check for ORA-105101
     when ORA_JAVA.EXCEPTION_THROWN then
        raisedException  := ORA_JAVA.LAST_EXCEPTION;
        message("Java Exception : " 
         || Exception_.getMessage(raisedException);
         ORA_JAVA.CLEAR_EXCEPTION;
     end;