Package edu.cnu.mdi.dialog

Class FileDialogs

java.lang.Object

edu.cnu.mdi.dialog.FileDialogs

public final class FileDialogs
extends Object

Centralized open/save dialogs for MDI applications.

The service consistently configures filters, remembers the last directory independently for each caller-supplied purpose, appends save extensions, and confirms overwrites. Methods return Optional.empty() when the user cancels, allowing action handlers to avoid chooser result-code boilerplate.

Purpose keys

A purpose is a stable application-defined identifier such as "problem-json" or "plot-export". Open and save share one remembered directory per purpose (not separate ones) -- in practice a file of a given kind is saved and reopened from the same folder far more often than not, so splitting the two would make the common case worse. A caller that genuinely wants independent histories can already get that by using distinct purpose strings for each (e.g. "shapefile-import" vs. "shapefile-export").

The remembered directory is persisted (via Preferences) across JVM restarts, keyed by purpose -- see lastDirectory(String) and rememberDirectory(String, Path), which are also available to callers that build their own JFileChooser (for filtering a caller cannot express as a simple extension list) but still want to participate in the same per-purpose directory memory. Before a purpose has any history (or its remembered directory no longer exists), Environment's data directory is used as the initial location -- this is purely a developer-configured default (see Environment.setDataDirectory(java.lang.String), typically set once at startup from a command-line argument or environment variable) and is not updated by every dialog use, so it stays whatever the developer intended rather than drifting to wherever the user last happened to browse.

Threading

Like other modal Swing dialogs, openFile(java.awt.Component, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType) and saveFile(java.awt.Component, java.lang.String, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType) must be invoked on the EDT. An IllegalStateException is thrown otherwise so an accidental worker thread call cannot create platform-dependent UI behavior. lastDirectory(String) and rememberDirectory(String, Path) have no such requirement.

Method Summary

Modifier and Type	Method	Description
static Optional<Path>	lastDirectory(String purpose)	Returns the best initial directory for purpose: the last remembered directory if it still exists, otherwise Environment's developer-configured data directory if that exists, otherwise empty -- leaving it to the caller (or, for openFile(java.awt.Component, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType)/saveFile(java.awt.Component, java.lang.String, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType), to JFileChooser's own platform default, typically the home directory).
static Optional<Path>	openFile(Component parent, String purpose, String title, FileType type)	Shows a single-file open dialog.
static void	rememberDirectory(String purpose, Path fileOrDirectory)	Remembers fileOrDirectory's directory (or itself, if it is already a directory) as the last visited directory for purpose, for lastDirectory(String) and subsequent openFile(java.awt.Component, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType)/saveFile(java.awt.Component, java.lang.String, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType) calls to pick up -- persisted across JVM restarts.
static Optional<Path>	saveFile(Component parent, String purpose, String title, String suggestedFilename, FileType type)	Shows a save dialog with extension normalization and overwrite confirmation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

openFile

public static Optional<Path> openFile(Component parent,
 String purpose,
 String title,
 FileType type)

Shows a single-file open dialog.

Parameters:

parent - parent component, or null

purpose - stable directory-history key

title - dialog title

type - accepted file type

Returns:

selected path, or empty if cancelled

saveFile

public static Optional<Path> saveFile(Component parent,
 String purpose,
 String title,
 String suggestedFilename,
 FileType type)

Shows a save dialog with extension normalization and overwrite confirmation.

Parameters:

parent - parent component, or null

purpose - stable directory-history key

title - dialog title

suggestedFilename - initial filename, or null for none

type - saved file type

Returns:

normalized target path, or empty if cancelled or overwrite declined

lastDirectory

public static Optional<Path> lastDirectory(String purpose)

Returns the best initial directory for purpose: the last remembered directory if it still exists, otherwise Environment's developer-configured data directory if that exists, otherwise empty -- leaving it to the caller (or, for openFile(java.awt.Component, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType)/saveFile(java.awt.Component, java.lang.String, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType), to JFileChooser's own platform default, typically the home directory).

Exposed for callers that build their own JFileChooser (for filtering FileType cannot express, such as compound extensions) but still want to share this same per-purpose directory memory with the rest of the application.

Parameters:

purpose - stable directory-history key

Returns:

the resolved initial directory, or empty

rememberDirectory

public static void rememberDirectory(String purpose,
 Path fileOrDirectory)

Remembers fileOrDirectory's directory (or itself, if it is already a directory) as the last visited directory for purpose, for lastDirectory(String) and subsequent openFile(java.awt.Component, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType)/saveFile(java.awt.Component, java.lang.String, java.lang.String, java.lang.String, edu.cnu.mdi.dialog.FileType) calls to pick up -- persisted across JVM restarts.

Parameters:

purpose - stable directory-history key

fileOrDirectory - a file just opened/saved, or a directory just navigated to