PathUtils.java

	/**
	 * @return same name StringBuilder returned
	 */
	public static @NonNull StringBuilder sanitizeFilenameMutate(@NonNull StringBuilder name) {
		return sanitizeFilenameMutate(name, 0, Integer.MAX_VALUE); // NOTE: end is checked vs name.length anyway
	}

	/**
	 * @param end can be -1 to process to end
	 * @return same name StringBuilder returned
	 */
	public static @NonNull StringBuilder sanitizeFilenameMutate(@NonNull StringBuilder name, int start, int end) {
		if(end < 0 || end >= name.length()) {
			end = name.length() - 1;
		}
		for(int i = start; i <= end; i++) {
			char c = name.charAt(i);
			if(!Character.isLetterOrDigit(c) && c != ' ' && c != '-' && c != '$' && c != '@' && c != '!' && c != '=' && c != '.' && c != ',') {
				name.setCharAt(i, '_');
			}			
		}
		return name;
	}

	/**
	 * Supports content:// paths as well
	 */
	public static @Nullable String getNameWithoutNumber(@Nullable String path) {
		if(path == null || path.length() == 0) {
			return path;
		}
		boolean isContent = isContentPath(path);
		
		int start = 0;
		int lastSlashIx = path.lastIndexOf('/');
		if(lastSlashIx != -1) {
			start = lastSlashIx + 1; 
		}
		
		final int len = path.length();
		for(; start < len; start++) {
			char ch = path.charAt(start);
			if(!(ch < 'A' || ch == '_')) {
				break;
			}
		}
		int dotPos = path.lastIndexOf('.');
		if(dotPos != -1 && dotPos > start) {

			path = path.substring(start, dotPos);
		}
		if(isContent) {
			path = Uri.decode(path);
		}
		
		return path;
	}

	public static boolean isContentPath(String path) {
		return path.length() > 8
				&& path.charAt(0) == 'c'
				&& path.charAt(1) == 'o'
				&& path.charAt(2) == 'n'
				&& path.charAt(3) == 't'
				&& path.charAt(4) == 'e'
				&& path.charAt(5) == 'n'
				&& path.charAt(6) == 't'
				&& path.charAt(7) == ':';
	}