A buffer is the jEdit term for an open file. Several buffers can be opened and edited at once; the combo box above the text area selects the buffer to edit. Different emblems are displayed next to buffer names in the list, depending the buffer's state; a red disk is shown for buffers with unsaved changes, a lock is shown for read-only buffers, and a spark is shown for new buffers which don't yet exist on disk.
In addition to the buffer combo box, various commands can also be used to select the buffer to edit.
View>Go to Previous Buffer (keyboard shortcut: Control-Page Up) switches to the previous buffer in the list.
View>Go to Next Buffer (keyboard shortcut: Control-Page Down) switches to the next buffer in the list.
View>Go to Recent Buffer (keyboard shortcut: Control-`) switches to the buffer that was being edited prior to the current one.
View>Show Buffer Switcher (keyboard shortcut: Alt-`) has the same effect as clicking on the buffer switcher combo box.
The maximum number of open buffers depends on available Java heap memory. When in the Java heap, a buffer uses approximately two and a half times it's size on disk. This overhead is caused by the file being stored internally in Unicode (see the section called “Character Encodings”), and various meta-data such as line numbers.
The status bar at the bottom of the view displays used and total Java heap memory; see the section called “The Status Bar” for details. This can give you a rough idea of how much memory the currently opened files are using. The Java heap grows if it runs out of room, but it only grows to a certain maximum size, and attempts to allocate Java objects that would grow the heap beyond this size fail with out-of-memory errors.
As a result, if the maximum heap size is set too low, opening large files or performing other memory-intensive operations can fail, even if you have a lot of free system memory.
To change the heap size on Windows, run “Set jEdit Parameters” from the “jEdit” group in the Programs menu. Then, in the resulting dialog box, under “Command line options for Java executable”, change the option that looks like so:
-mx32m |
(See the section called “Starting jEdit” for more information about the “Set jEdit Parameters” dialog box.)
On Unix, edit the jedit shell script and change the line that looks like so:
JAVA_HEAP_SIZE=32 |
In both cases, replace “32” with the desired heap size, in megabytes.