System.out.println(Integer.toHexString(-1)); // ffffffff
System.out.println(Integer.toHexString(Integer.MIN_VALUE)); // 80000000

String dirname = Integer.toHexString(dirname.hashCode()); // never has minus sign

long longHash = intHash;
 long nonNegativeLongHash = longHash & ((1L << 32) - 1);
 String unsignedHex = Long.toHexString(nonNegativeLongHash);