A DESCRIPTION OF THE REQUEST : The current implementation of UUID#fromString(String) is as follows: ``` public static UUID fromString(String name) { String[] components = name.split("-"); if (components.length != 5) throw new IllegalArgumentException("Invalid UUID string: "+name); for (int i=0; i<5; i++) components[i] = "0x"+components[i]; long mostSigBits = Long.decode(components[0]).longValue(); mostSigBits <<= 16; mostSigBits |= Long.decode(components[1]).longValue(); mostSigBits <<= 16; mostSigBits |= Long.decode(components[2]).longValue(); long leastSigBits = Long.decode(components[3]).longValue(); leastSigBits <<= 48; leastSigBits |= Long.decode(components[4]).longValue(); return new UUID(mostSigBits, leastSigBits); } ``` To convince Long#decode(String) to parse the string as a hexadecimal value, the method prepends "0x" to be beginning of each element of the `components` array. We could instead use `Long#parseLong(String, int)` and avoid five string concatenations per call to `UUID#fromString(String)`: ``` public static UUID fromString(final String name) { String[] components = name.split("-"); if (components.length != 5) throw new IllegalArgumentException("Invalid UUID string: "+name); long mostSigBits = Long.parseLong(components[0], 16); mostSigBits <<= 16; mostSigBits |= Long.parseLong(components[1], 16); mostSigBits <<= 16; mostSigBits |= Long.parseLong(components[2], 16); long leastSigBits = Long.parseLong(components[3], 16); leastSigBits <<= 48; leastSigBits |= Long.parseLong(components[4], 16); return new UUID(mostSigBits, leastSigBits); } ``` JUSTIFICATION : This approach eliminates five string concatenations per call to `UUID#fromString(String)` and also eliminates some unnecessary unboxing (the calls to `Long#longValue()`). With these changes, jmh shows an improvement in throughput of nearly 50%: ``` Benchmark Mode Cnt Score Error Units UuidBenchmark.benchmarkUuidFromString thrpt 40 1544067.340 ± 39521.275 ops/s UuidBenchmark.benchmarkUuidFromStringWithRadix thrpt 40 2284632.364 ± 53192.174 ops/s ```