SuiHome — How the Sui Home Directory Is Resolved¶

Purpose¶

SuiHome is a static field in the Sui class that holds the path to the directory where Sui stores its configuration and property files (e.g. SuiSys.pro, SuiSheetProp.pro, SuiConnPref.pro). It is resolved once at startup and never changes during the lifetime of the application.

`HomeDrive` — Prerequisite¶

Before SuiHome is resolved, the drive letter (HomeDrive) is determined in main():

main(args)
  ├─ args[0] present?  → HomeDrive = first character of args[0]  (e.g. "C")
  └─ otherwise         → HomeDrive = System.getenv("HOMEDRIVE")  (e.g. "C")

HomeDrive is used as a symbolic token (&homedrive) inside Sui.ini and is also available via Sui.GetHomeDrive().

Resolution Order¶

SuiHome is determined by working through four candidates in order, stopping at the first one that succeeds:

1. Sui.ini  →  SuiHome=<folder>[;]  (if the folder exists, or &current_path/&current_folder is used)
2. <user.home>\AppData\Sui\        (if the folder exists)
3. <user.dir>\                     (current directory, if Sui can write to it)
4. <user.home>\AppData\Sui\        (fallback — folder is created if missing)

Step 1 — `Sui.ini` (explicit override)¶

Sui reads Sui.ini from the current working directory. The file is scanned line by line for a SuiHome=...; statement.

Syntax:

SuiHome=<folder>[;]

The trailing semicolon is optional — both SuiHome=C:\SuiData; and SuiHome=C:\SuiData are accepted. When a semicolon is present, any text after it is ignored (so SuiHome=C:\SuiData; # comment still works). The value is trimmed of leading/trailing whitespace before use.

Symbolic tokens that can be embedded in <folder>:

Token	Resolved to
`&current_path`	The directory Sui was started from (`user.dir`). Highest-priority token — resolves unconditionally without a directory-existence check. Use this to keep all Sui config files alongside the Sui jar / launch script.
`&current_folder`	Alias of `&current_path` — identical behaviour.
`&homedrive`	`HomeDrive` (drive letter, e.g. `C`)
`&user.name`	Java system property `user.name`
`&user.home`	Java system property `user.home`

Examples:

SuiHome=&current_path;
SuiHome=&current_folder              (no trailing semicolon — also accepted)
SuiHome=C:\SuiData
SuiHome=&homedrive:\Users\&user.name\SuiData;
SuiHome=&user.home\AppData\Sui;

When SuiHome=&current_path (or &current_folder) is used, the path is set to the startup directory immediately — no File.isDirectory() check is performed, because the current directory always exists. For all other values, after token substitution the path is tested with File.isDirectory(). If the folder exists, Folder is set to that path and steps 2–4 are skipped. If the folder does not exist, Folder remains null and the next step is tried.

If Sui.ini is missing or cannot be read, the whole block is caught and Folder stays null.

Other settings parsed from Sui.ini (processed in the same loop):

Key	Effect
`Font=<name>,<size>;`	Sets the global Swing UI font
`LookandFeel=<class>;`	Records the Look & Feel class name to apply (see below)
`Pyjamas=true\\|false;`	Enables/disables Pyjamas report formatting

Step 2 — `user.home\AppData\Sui\`¶

If no valid SuiHome was found in Sui.ini, Sui checks whether the folder <user.home>\AppData\Sui\ exists:

SuiHome = userHome + "\\AppData\\Sui\\";
f = new File(SuiHome);
if (f.isDirectory()) → use it

This is the standard Windows per-user application data location.

Step 3 — Current directory (`user.dir`)¶

If the AppData\Sui folder does not exist either, Sui falls back to the current working directory:

SuiHome = userDir + "\\";

Write-access check¶

After steps 1–3 have selected a candidate, Sui verifies it can actually write there by attempting to create and immediately delete a temporary file:

File f = new File(SuiHome + "\\test.fil");
f.createNewFile();  // succeeds → delete and proceed

If the write test fails (IOException), Sui falls back to step 4.

Step 4 — Fallback: create `user.home\AppData\Sui\`¶

If the write test throws (or if user.home was empty and none of the earlier steps succeeded), Sui attempts to create the AppData\Sui folder under the user home directory:

SuiHome = userHome + "\\AppData\\Sui\\";
new File(SuiHome).mkdir();

A second catch block handles the case where even mkdir() fails (e.g. restricted environment), printing a stack trace but continuing.

Final value¶

Once resolved, SuiHome always ends with a backslash (\), so file references can be built by simple concatenation:

String propsFile = SuiHome + "SuiSys.pro";

The final path is logged to the console along with user.dir and user.home:

Final: C:\Users\kjell\AppData\Sui\
****************************************************************
User Directory     = C:\SuiVsCode\suidev080
Home Directory     = C:\Users\kjell
Sui Home Directory = C:\Users\kjell\AppData\Sui\
****************************************************************

Summary Flow¶

main()
  └─ HomeDrive = args[0][0]  OR  HOMEDRIVE env var

Sui constructor
  ├─ Read Sui.ini
  │     └─ SuiHome=...[;]  → expand tokens → folder exists?  → Folder = path
  │                          (semicolon optional)
  │
  ├─ Folder set?
  │     yes → SuiHome = Folder + "\"
  │     no  → userHome available?
  │               yes → SuiHome = userHome + "\AppData\Sui\"  (if dir exists)
  │                     else → SuiHome = userDir + "\"
  │               no  → SuiHome = userDir + "\"
  │
  └─ Write test (create/delete test.fil)
        success → done
        fail    → SuiHome = userHome + "\AppData\Sui\"  (mkdir if needed)

Look and Feel¶

How it is set¶

The LookandFeel key in Sui.ini is read during startup (same loop as SuiHome) and stored in the static field LfToUse. The value is the fully-qualified class name of the Look & Feel implementation.

setLF() is called later in the startup sequence, after drivers and jars have been loaded. It applies the Look & Feel in two passes:

Pass 1 — SUI.LF property (runtime profile)
Reads the SUI.LF key from the application property store (SuiSys.pro). If set, it iterates UIManager.getInstalledLookAndFeels() to find a matching installed L&F by name and applies it. This allows the user to switch themes at runtime and have the choice remembered.

Pass 2 — LfToUse from Sui.ini
If LfToUse is not null, it calls UIManager.setLookAndFeel(LfToUse) directly with the class name string. This path is used for third-party L&Fs (like FlatLaf) that are not pre-registered with UIManager. After applying, SwingUtilities.updateComponentTreeUI(cont) is called to repaint all existing components, and JFrame.setDefaultLookAndFeelDecorated(true) enables native window decoration from the L&F.

If LfToUse is null (no LookandFeel key in Sui.ini), the connection panel background is set to the system menu colour as a minimal default.

Any exception during L&F loading is caught and logged — Sui continues with whatever L&F was in effect before the failure.

FlatLaf examples¶

FlatLaf is a modern flat Look & Feel for Java Swing. Its jar must be on the classpath (or loaded via Sui's jar loader) for these to work.

Built-in FlatLaf themes:

# Light themes
LookandFeel=com.formdev.flatlaf.FlatLightLaf;
LookandFeel=com.formdev.flatlaf.FlatIntelliJLaf;

# Dark themes
LookandFeel=com.formdev.flatlaf.FlatDarkLaf;
LookandFeel=com.formdev.flatlaf.FlatDarculaLaf;

FlatLaf IntelliJ Themes (requires flatlaf-intellij-themes jar):

# Popular light IntelliJ themes
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatArcOrangeIJTheme;
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatGitHubIJTheme;
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatSolarizedLightIJTheme;

# Popular dark IntelliJ themes
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatOneDarkIJTheme;
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatDraculaIJTheme;
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatNordIJTheme;
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatSolarizedDarkIJTheme;
LookandFeel=com.formdev.flatlaf.intellijthemes.FlatMaterialDesignDarkIJTheme;

Combining with other Sui.ini settings:

SuiHome=C:\Users\kjell\AppData\Sui;
Font=JetBrains Mono,13;
LookandFeel=com.formdev.flatlaf.FlatDarkLaf;
Pyjamas=false;

Note: The FlatLaf jar must be present. If it is not on the classpath, setLF() will catch the ClassNotFoundException and log "Loading look and feel failed, lf=: com.formdev.flatlaf.FlatDarkLaf" to the console — Sui continues with the default Java L&F.