What Peoplecode syntax is required to pass an enum constant to a class method of a java object using reflection?

Question

I am using the Apache POI class SXSSFWorkbook through Peoplecode to write large amounts of data to an excel file. I know very little Java but was able to put together code which produces the file using java reflection through Peoplecode. Unfortunately there is a bug in Peoplecode which makes it necessary to use reflection even when a method is not overloaded.

As an example, to execute the following java code:

SXSSFWorkbook workbook = new SXSSFWorkbook(100); /* 100 rows of accessible data */
SXSSFSheet sheet = workbook.getSheet(&name);

The equivalent in Peoplecode using java reflection is:

   &_workbook = CreateJavaObject("org.apache.poi.xssf.streaming.SXSSFWorkbook", 100);
   &_sheet = GetJavaClass("org.apache.poi.xssf.streaming.SXSSFSheet");

   Local JavaObject &javaString = CreateJavaObject("java.lang.String", &name);
   Local JavaObject &stringType = CreateJavaObject("java.lang.Class[]", &javaString.getClass());
   Local JavaObject &getSheet = &_class.getDeclaredMethod("getSheet", &stringType);
   Local JavaObject &args = CreateJavaObject("java.lang.Object[]", &javaString);
   &_sheet = &getSheet.invoke(&_workbook, &args);

This technique works for all the methods using String, Integer, boolean as a parameter value.

Now I need to disable the Zip64 extensions by using the enum constant "Never".

Required java code: workbook.setZip64Mode(Zip64Mode.Never);

Updated: I tried the following

   &_workbook = CreateJavaObject("org.apache.poi.xssf.streaming.SXSSFWorkbook");

   &_class = &_workbook.getClass();
      Local JavaObject &javaString = GetJavaClass("org.apache.commons.compress.archivers.zip.Zip64Mode").valueOf("Never");   
   Local JavaObject &stringType = CreateJavaObject("java.lang.Class[]", GetJavaClass("org.apache.commons.compress.archivers.zip.Zip64Mode"));
   Local JavaObject &setZip64Mode = &_class.getDeclaredMethod("setZip64Mode", &stringType);
   Local JavaObject &args = CreateJavaObject("java.lang.Object[]", &javaString);
   
   &setZip64Mode.invoke(&_workbook, &args);
   &_class = Null;

This executes but does not change the size of the output file at all.
GetJavaClass(org.apache.commons.compress.archivers.zip.Zip64Mode).valueOf("Never"); returns a string value of "org.apache.commons.compress.archivers.zip.Zip64Mode" instead of "Never".

setZip64Mode(org.apache.commons.compress.archivers.zip.Zip64Mode zip64Mode)

What am I missing?

Answer 1

After a lot of research and additional information the code below is working as expected.

   &_class = &_workbook.getClass();
   Local JavaObject &javaString = GetJavaClass("org.apache.commons.compress.archivers.zip.Zip64Mode").valueOf("Never");   
   Local JavaObject &stringType = CreateJavaObject("java.lang.Class[]", GetJavaClass("org.apache.commons.compress.archivers.zip.Zip64Mode"));
   Local JavaObject &setZip64Mode = &_class.getDeclaredMethod("setZip64Mode", &stringType);
   Local JavaObject &args = CreateJavaObject("java.lang.Object[]", &javaString);
   
   &setZip64Mode.invoke(&_workbook, &args);
   &_class = Null;

However, it was discovered that Peoplecode gives the same error if a java method does not exist OR if it was not called with the correct syntax (parameter type)

The code below can be used instead of the reflection code shown above:

Local JavaObject &enumValue = CreateJavaObject("java.lang.String", "Never");
&_workbook.setZip64Mode(GetJavaClass("org.apache.commons.compress.archivers.zip.Zip64Mode").valueOf(&enumValue));

Although the file size did not change, it was observed to not produce a zip-bomb error when opened for reading. This was the actual problem. To check whether the file could successfully be processed, Araxis-Merge was used to validate the file.

Example of Zip-Bomb error and valid file