---
category: swing
folder: DarkMode
title: JEditorPaneのStyleSheetをLight・Darkテーマに合わせて切り替える
tags: [JEditorPane, StyleSheet, LookAndFeel, Toolkit, PropertyChangeListener]
author: aterai
pubdate: 2025-04-07T09:41:23+09:00
description: JEditorPaneのStyleSheetを起動時のシステムテーマがLightかDarkかなどに応じて切り替えるよう設定します。
image: https://drive.google.com/uc?id=1rNhaj-mqEkjn2ntU4yNaMPj-DJOdzBfW
hreflang:
href: https://java-swing-tips.blogspot.com/2025/04/switch-jeditorpanes-stylesheet-to-light.html
lang: en
---
* Summary [#summary]
`JEditorPane`の`StyleSheet`を起動時のシステムテーマが`Light`か`Dark`かなどに応じて切り替えるよう設定します。
#download(https://drive.google.com/uc?id=1rNhaj-mqEkjn2ntU4yNaMPj-DJOdzBfW)
* Source Code Examples [#sourcecode]
#code(link){{
public static void updateTheme(JEditorPane editor) {
updateTheme(editor, isDarkMode());
}
public static void updateTheme(JEditorPane editor, boolean isDark) {
EditorKit kit = editor.getEditorKit();
HTMLEditorKit htmlEditorKit;
if (kit instanceof HTMLEditorKit) {
htmlEditorKit = (HTMLEditorKit) kit;
} else {
htmlEditorKit = new HTMLEditorKit();
}
if (isDark) {
htmlEditorKit.setStyleSheet(makeDarkStyleSheet());
editor.setBackground(new Color(0x1E_1F_22));
} else {
htmlEditorKit.setStyleSheet(makeLightStyleSheet());
editor.setBackground(new Color(0xEE_EE_EE));
}
editor.setEditorKit(htmlEditorKit);
}
public static boolean isDarkMode() {
boolean isDark;
String os = System.getProperty("os.name").toLowerCase(Locale.ENGLISH);
if (os.contains("windows")) {
isDark = isWindowsDarkMode();
} else if (os.contains("linux")) {
isDark = isLinuxDarkMode();
} else if (os.contains("mac")) {
isDark = isMackDarkMode();
} else {
isDark = false;
}
return isDark;
}
public static String getProcessOutput(String... cmd)
throws IOException, InterruptedException {
ProcessBuilder builder = new ProcessBuilder(cmd);
builder.redirectErrorStream(true);
Process p = builder.start();
String str;
try (BufferedReader pr = new BufferedReader(
new InputStreamReader(p.getInputStream()))) {
str = pr.lines().collect(Collectors.joining(System.lineSeparator()));
}
return str;
}
public static boolean isWindowsDarkMode() {
String[] cmd = {
"powershell.exe",
"Get-ItemPropertyValue",
"-Path",
"HKCU:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize",
"-Name",
"AppsUseLightTheme;"
};
boolean isDarkMode;
try {
String str = getProcessOutput(cmd).trim();
isDarkMode = Objects.equals("0", str);
} catch (IOException | InterruptedException ex) {
Logger.getGlobal().severe(ex::getMessage);
isDarkMode = false;
}
return isDarkMode;
}
public static boolean isLinuxDarkMode() {
Toolkit tk = Toolkit.getDefaultToolkit();
Object theme = tk.getDesktopProperty("gnome.Net/ThemeName");
return Objects.toString(theme).contains("dark");
}
public static boolean isMackDarkMode() {
return false;
}
// https://raw.githack.com/google/code-prettify/master/styles/index.html
// Prettify Themes Gallery
public static StyleSheet makeLightStyleSheet() {
StyleSheet styleSheet = new StyleSheet();
styleSheet.addRule("pre{background:#eeeeee}");
styleSheet.addRule(".str{color:#008800}");
styleSheet.addRule(".kwd{color:#000088}");
styleSheet.addRule(".com{color:#880000}");
styleSheet.addRule(".typ{color:#660066}");
styleSheet.addRule(".lit{color:#006666}");
styleSheet.addRule(".pun{color:#666600}");
styleSheet.addRule(".pln{color:#000000}");
styleSheet.addRule(".tag{color:#000088}");
styleSheet.addRule(".atn{color:#660066}");
styleSheet.addRule(".atv{color:#008800}");
styleSheet.addRule(".dec{color:#660066}");
return styleSheet;
}
public static StyleSheet makeDarkStyleSheet() {
StyleSheet styleSheet = new StyleSheet();
styleSheet.addRule("pre{background:#1e1f22}");
styleSheet.addRule(".str{color:#ffa0a0}");
styleSheet.addRule(".kwd{color:#f0e68c;font-weight:bold}");
styleSheet.addRule(".com{color:#87ceeb}");
styleSheet.addRule(".typ{color:#98fb98}");
styleSheet.addRule(".lit{color:#cd5c5c}");
styleSheet.addRule(".pun{color:#ffffff}");
styleSheet.addRule(".pln{color:#ffffff}");
styleSheet.addRule(".tag{color:#f0e68c;font-weight:bold}");
styleSheet.addRule(".atn{color:#bdb76b;font-weight:bold}");
styleSheet.addRule(".atv{color:#ffa0a0}");
styleSheet.addRule(".dec{color:#98fb98}");
return styleSheet;
}
}}
* Description [#explanation]
* Description [#description]
- `OS`が`Windows`の場合、個人用設定の色をライト、ダークで切り替えても`Swing`アプリ側でそのイベントを取得できない
-- `Windows 7`などでは[[DesktopPropertyの変更を監視する>Swing/DesktopProperty]]のように`Toolkit`に`PropertyChangeListener`を追加することで画面の配色変更を取得可能だったが、`Windows 10`や`Windows 11`では動作しない？
-- このサンプルでは、起動時や`JRadioButtonMenuItem`でテーマを手動切り替えしたときに、レジストリから`HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize`の値を取得して`0`の場合は`Dark`テーマと判断し、`StyleSheet`の切り替えを実行
-- [https://www.tenforums.com/tutorials/24038-change-default-app-windows-mode-light-dark-theme-windows-10-a.html Change Default App & Windows Mode to Light or Dark Theme in Windows 10 | Tutorials]
-- [https://gist.github.com/HanSolo/7cf10b86efff8ca2845bf5ec2dd0fe1d Detector: A plain Java class that offers some utility methods to detect dark theme on MacOS and Windows · GitHub]
- `OS`が`Linux(Ubuntu+gnome)`の場合、設定の外観、スタイルをデフォルト(ライト)、ダークで切り替えると、`Swing`アプリ側でもそのイベントを取得可能
-- `GTKLookAndFeel`はデフォルトでスタイル切り替えが発生すると`SynthTheme`を切り替えて各コンポーネントの配色を変更している
--- [https://docs.oracle.com/javase/jp/6/technotes/guides/swing/1.4/Post1.4.html#gtk GTK+ の Look & Feel - Java 2 SDK, v1.4 からの Swing の変更点]
-- そのため以下のように`Toolkit`にデスクトッププロパティを`gnome.Net/ThemeName`として`PropertyChangeListener`を追加すればスタイル切り替えイベントを取得可能で、このサンプルではテーマ名に`dark`が含まれる場合は`Dark`テーマと判断し`StyleSheet`の切り替えを実行している
#code{{
String key = "gnome.Net/ThemeName";
Toolkit.getDefaultToolkit().addPropertyChangeListener(key, e -> {
if (sys.isSelected()) {
boolean dark = Objects.toString(e.getNewValue()).contains("dark");
ThemeUtils.updateTheme(editor, dark);
loadHtml(editor);
}
});
}}
- `OS`が`Mac`の場合には、このサンプルは未対応だが、以下のサイトの方法で対応可能
-- [https://github.com/Dansoftowner/jSystemThemeDetector Dansoftowner/jSystemThemeDetector: Java library for detecting that the (desktop) operating system uses dark UI theme or not]
-- [https://gist.github.com/HanSolo/7cf10b86efff8ca2845bf5ec2dd0fe1d Detector: A plain Java class that offers some utility methods to detect dark theme on MacOS and Windows · GitHub]
* Reference [#reference]
- [https://github.com/Dansoftowner/jSystemThemeDetector Dansoftowner/jSystemThemeDetector: Java library for detecting that the (desktop) operating system uses dark UI theme or not]
- [https://gist.github.com/HanSolo/7cf10b86efff8ca2845bf5ec2dd0fe1d Detector: A plain Java class that offers some utility methods to detect dark theme on MacOS and Windows · GitHub]
-- via: [https://harmoniccode.blogspot.com/2021/02/poor-mans-dark-mode-detection.html Harmonic Code: "Poor man's" dark mode detection]
- [https://stackoverflow.com/questions/8149828/read-the-output-from-java-exec runtime - read the output from java exec - Stack Overflow]
- [https://www.tenforums.com/tutorials/24038-change-default-app-windows-mode-light-dark-theme-windows-10-a.html Change Default App & Windows Mode to Light or Dark Theme in Windows 10 | Tutorials]
- [https://raw.githack.com/google/code-prettify/master/styles/index.html Prettify Themes Gallery]
- [[DesktopPropertyの変更を監視する>Swing/DesktopProperty]]
- [https://docs.oracle.com/javase/jp/6/technotes/guides/swing/1.4/Post1.4.html#gtk GTK+ の Look & Feel - Java 2 SDK, v1.4 からの Swing の変更点]
* Comment [#comment]
#comment
#comment