String (@NotNull String name) { int startTrimmed = -1; int endTrimmed = -1; for (int i = 0; i < name.length(); i++) { char c = name.charAt(i); if (startTrimmed == -1) { if (!isFileSeparator(c)) { startTrimmed = i; } } else if (endTrimmed == -1) { if (isFileSeparator(c)) { endTrimmed = i; } } else if (!isFileSeparator(c)) { return null; // there are slashes in the middle } } if (startTrimmed == -1) return null; if (endTrimmed == -1) return name.substring(startTrimmed); if (startTrimmed == endTrimmed) return null; return name.substring(startTrimmed, endTrimmed); }