In a world of untrusted code and SecurityManagers, it was critical that strings be immutable so a data race couldn’t bypass a policy decision. The JVM doesn’t h

In a world of untrusted code and SecurityManagers, it was critical that strings be immutable so a data race couldn’t bypass a policy decision. The JVM doesn’t have immutable arrays, so string methods carefully protected the embedded array from tampering, and couldn’t be overridden. Most classes don’t have this problem. The original authors of a class don’t know what I’m trying to do, and they don’t bear consequences if I (a consenting adult) get it wrong.