Doing more with files with Java and PeopleCode

PeopleCode’s native file APIs are fine for reading and writing, but they give you almost nothing when it comes to metadata. You can’t ask for a file’s size, its last-modified time, or pull the extension off a full path without writing your own string parsing. java.io.File fills those gaps, and a thin application-class wrapper turns it into something you can call from anywhere in your codebase.

The raw approach

The starting point is still useful to see on its own. With a full path string, you can get a java.io.File reference and ask it for anything the Java API exposes.

Local string &fileName;

&fileName = "/path/to/file/myFile.txt";

/* Get a reference to a file object */
Local JavaObject &f = CreateJavaObject("java.io.File", &fileName);

/* Format the last modified time as a string */
Local JavaObject &sdf = CreateJavaObject("java.text.SimpleDateFormat", "MM/dd/yyyy HH:mm:ss");
Local string &mod = &sdf.format(&f.lastModified());

/* Get the size in bytes */
Local number &SIZE = &f.length();

/* Rename it */
Local string &newFileName = "/newPath/to/File/myfile.txt.backup";
Local JavaObject &fBU = CreateJavaObject("java.io.File", &newFileName);
Local boolean &b2 = &f.renameTo(&fBU);

That’s handy, but copying those three or four lines into every project eventually turns into a mess. Wrapping it in an application class gives you one place to maintain it.

A reusable fileHelper class

The class signature:

class fileHelper
   method getFileName(&filenameAndPath As string) Returns string;
   method getFileExtension(&filenameAndPath As string) Returns string;
   method getFileNameWithoutExtension(&filenameAndPath As string) Returns string;
   method getDirectory(&filenameAndPath As string) Returns string;
   method getFileSizeinMB(&filenameAndPath As string) Returns number;
   method getLastDateModified(&filenameAndPath As string) Returns string;
   method touchFile(&filenameAndPath As string) Returns boolean;
end-class;

The path-parsing methods (getFileName, getFileExtension, getFileNameWithoutExtension, getDirectory) are pure PeopleCode string work. The metadata methods (getFileSizeinMB, getLastDateModified, touchFile) lean on java.io.File and guard themselves with FileExists(..., %FilePath_Absolute) so they don’t blow up on missing files.

getFileName

Scans the path from right to left for the last / and returns everything after it.

method getFileName
   /+ &filenameAndPath as String +/
   /+ Returns String +/

   Local integer &start;
   Local string &filename;

   &start = Len(&filenameAndPath) - 1;
   While &start >= 1
      If Find("/", &filenameAndPath, &start) > 0 Then
         &filename = Substring(&filenameAndPath, (&start + 1), Len(&filenameAndPath));
         Break;
      Else
         &start = &start - 1
      End-If
   End-While;

   Return &filename;
end-method;

getFileNameWithoutExtension

Strips the extension off whatever getFileName returns.

method getFileNameWithoutExtension
   /+ &filenameAndPath as String +/
   /+ Returns String +/

   Local integer &start;
   Local string &filename;

   &filename = %This.getFileName(&filenameAndPath);

   &start = Len(&filename) - 1;
   While &start >= 1
      If Find(".", &filename, &start) > 0 Then
         Local string &fileNameNoExtension;
         &fileNameNoExtension = Substring(&filename, 1, &start - 1);
         Break;
      Else
         &start = &start - 1
      End-If
   End-While;

   Return &fileNameNoExtension
end-method;

getFileExtension

Pulls everything after the first . in the filename.

method getFileExtension
   /+ &filenameAndPath as String +/
   /+ Returns String +/

   Local integer &start;
   Local string &filename;

   &filename = %This.getFileName(&filenameAndPath);
   &start = Find(".", &filename, 1);

   If &start > 0 Then
      Local string &fileExtension;
      &fileExtension = Substring(&filename, (&start + 1), Len(&filename));
      Return &fileExtension;
   Else
      Return "";
   End-If;
end-method;

getDirectory

Returns the path up to (but not including) the filename.

method getDirectory
   /+ &filenameAndPath as String +/
   /+ Returns String +/

   Local integer &start;
   Local string &filename;
   Local string &directory;

   &filename = %This.getFileName(&filenameAndPath);
   &start = Find(&filename, &filenameAndPath, 1);
   &directory = Substring(&filenameAndPath, 1, &start - 1);
   Return &directory;
end-method;

getFileSizeinMB

java.io.File.length() returns bytes; divide by 1048576 to get megabytes and round to six decimal places. Returns 0 if the file doesn’t exist.

method getFileSizeinMB
   /+ &filenameAndPath as String +/
   /+ Returns Number +/
   Local number &return;

   &return = 0;

   If FileExists(&filenameAndPath, %FilePath_Absolute) Then
      Local JavaObject &f = CreateJavaObject("java.io.File", &filenameAndPath);
      &return = &f.length();

      /* CONVERT FROM BYTES TO MEGABYTES */
      &return = &return / 1048576;
      &return = Round(&return, 6);
   End-If;

   Return &return;
end-method;

getLastDateModified

Formats File.lastModified() (Unix epoch milliseconds) through SimpleDateFormat so you get back a string you can display or log.

method getLastDateModified
   /+ &filenameAndPath as String +/
   /+ Returns String +/
   If FileExists(&filenameAndPath, %FilePath_Absolute) Then
      Local JavaObject &f = CreateJavaObject("java.io.File", &filenameAndPath);
      Local JavaObject &sdf = CreateJavaObject("java.text.SimpleDateFormat", "MM/dd/yyyy HH:mm:ss");
      Local string &mod;
      &mod = &sdf.format(&f.lastModified());
      Return &mod;
   Else
      Return "";
   End-If;
end-method;

touchFile

The Unix-style touch: update the last-modified time to now. Useful when you want a downstream process watching mtimes to notice a file without rewriting its contents.

method touchFile
   /+ &filenameAndPath as String +/
   /+ Returns Boolean +/

   If FileExists(&filenameAndPath, %FilePath_Absolute) Then
      Local JavaObject &joCurrFile = CreateJavaObject("java.io.File", &filenameAndPath);
      Local JavaObject &jlongtime = CreateJavaObject("java.util.Date");
      Local number &modifytime = &jlongtime.getTime();
      Local boolean &filemodified = &joCurrFile.setLastModified(&modifytime);
      Return &filemodified;
   Else
      Return False;
   End-If;
end-method;

Using it

Assuming you’ve put this class in an app package like CHG_UTIL:fileHelper:

Import CHG_UTIL:fileHelper;

Local CHG_UTIL:fileHelper &fh = create CHG_UTIL:fileHelper();
Local string &path = "/psft/app/files/report.txt";

Local string &name = &fh.getFileName(&path);              /* report.txt   */
Local string &ext  = &fh.getFileExtension(&path);         /* txt          */
Local string &dir  = &fh.getDirectory(&path);             /* /psft/app/files/ */
Local number &mb   = &fh.getFileSizeinMB(&path);
Local string &mod  = &fh.getLastDateModified(&path);

Caveats and things to tighten

The code above works, but there are a few sharp edges worth flagging before you paste it straight into production:

• getFileNameWithoutExtension can return an uninitialised value. &fileNameNoExtension is declared inside the If branch. For a filename with no . at all, the method returns an empty/uninitialised local. Declare it up front and default it to &filename so extensionless names round-trip cleanly.
• getFileExtension finds the first dot, not the last. For a name like report.2026.tar.gz it returns 2026.tar.gz. Usually you want gz — reuse the right-to-left scan pattern from getFileName to find the last . instead.
• getDirectory uses Find for the filename inside the full path. If a parent folder happens to share a prefix with the filename, the directory cut can land in the wrong place. Safer: find the last / by scanning from the right and substring up to that index.
• touchFile always sets mtime to now. That matches the Unix touch contract, so no change needed — just don’t confuse it with “verify the file can be modified.”
• All java-backed methods silently no-op if the file is missing. getFileSizeinMB returns 0, getLastDateModified returns "", and touchFile returns False. Depending on your caller, you may want to distinguish “file missing” from “file is zero bytes” or “touch failed for another reason.”

Fold those fixes in before you use this in an App Engine that runs unattended — path parsers that silently return wrong data are a pain to debug.