Mac OS-Related Issues

Inside Macintosh: Programming With JManager /

Appendix B - Mac OS-Related Issues

The Mac OS runtime environment has some restrictions and peculiarities that you should keep in mind when writing either Java code or Mac OS-based code that interacts with Java code. Table B-1 describes these issues and possible solutions.

Table B-1 Mac OS-related issues
Description Possible limitations Solutions
31-character limit on filenames. Java class filenames can easily exceed 31 characters. Class files stored in zip files can have names longer than 31 characters.
Only the active frame's menu bar is visible. Some Java programs may specify more than one menu bar. N/A
Cooperative rather than preemptive multitasking. Some odd timing effects may occur. N/A
File and directory delimiter character is a colon (:), not a slash (/). (The slash is a valid character in a filename.) May cause confusion or odd behavior when working with file systems that return a URL or similar path (such as not finding a file located in a folder named Reports May/June). Embedded slash characters should be encoded as a percent sign (%) plus the hex ASCII value (that is, %2F).
A space is a valid character in a Mac OS filename. May cause unexpected interpretations of strings obtained from other platforms. Embedded space characters should be encoded as a percent sign (%) plus the hex ASCII value (that is %20).

The mechanism for handling dynamically linked libraries (DLLs) on the Mac OS platform is the Code Fragment Manager (CFM). For information about the Code Fragment Manager, see Mac OS Runtime Architectures and Inside Macintosh: PowerPC System Software.
In addition, the standards for the Mac OS user interface are often different from those on other platforms. Here are a few things to keep in mind:

The Preferences menu item is typically stored under the Edit menu (not the File menu).
Dialog boxes typically have the OK button located near the lower right corner, with the Cancel button to its immediate left.
The default grayscale appearance of windows and menus in System 7.6 and later is lighter than the corresponding Windows 95 appearance.

Description	Possible limitations	Solutions
31-character limit on filenames.	Java class filenames can easily exceed 31 characters.	Class files stored in zip files can have names longer than 31 characters.
Only the active frame's menu bar is visible.	Some Java programs may specify more than one menu bar.	N/A
Cooperative rather than preemptive multitasking.	Some odd timing effects may occur.	N/A
File and directory delimiter character is a colon (`:`), not a slash (`/`). (The slash is a valid character in a filename.)	May cause confusion or odd behavior when working with file systems that return a URL or similar path (such as not finding a file located in a folder named `Reports May/June`).	Embedded slash characters should be encoded as a percent sign (`%`) plus the hex ASCII value (that is, `%2F`).
A space is a valid character in a Mac OS filename.	May cause unexpected interpretations of strings obtained from other platforms.	Embedded space characters should be encoded as a percent sign (`%`) plus the hex ASCII value (that is `%20`).