Finalized in Java 17 (JEP 356). The Problem with Java’s Old PRNG API Java’s random number generation before Java 17 had several problems: 1. java.util.Random has poor statistical properties. The default PRNG algorithm is a 48-bit linear congruential generator (LCG). It fails many statistical tests (spectral test, birthday test). Its 2^48 period is short — exhaustible in seconds on modern hardware. 2. No common interface. java.util.Random, java.util.concurrent.ThreadLocalRandom, java.util.SplittableRandom, and java.