RTEditor/src/main/java/com/onegravity/rteditor/fonts/FontManager.java
public static void preLoadFonts(final Context context) {
        new Thread(() -> {
            synchronized (ASSET_FONTS_BY_NAME) {
                getAssetFonts(context);
            }
            synchronized (SYSTEM_FONTS_BY_NAME) {
                getSystemFonts();
            }
        }).start();
    }
public static void preLoadFonts(final Context context) {
        new Thread(() -> {
            synchronized (ASSET_FONTS_BY_NAME) {
                getAssetFonts(context);
            }
            synchronized (SYSTEM_FONTS_BY_NAME) {
                getSystemFonts();
            }
        }).start();
    }
Use this method to preload fonts asynchronously e.g. when the app starts up.