Thread Without Join (ARCH4041)

Key java.async.thread-without-join · Severity warning · Category async

When a thread is created and started but never joined, the spawning scope may exit before the thread completes, leaving its work and exceptions unobserved.

Incorrect

void load() {
    Thread t = new Thread(this::fetch);
    t.start();                 // no join
}                              // method returns before work finishes

Correct

void load() throws InterruptedException {
    Thread t = new Thread(this::fetch);
    t.start();
    t.join();                  // wait for completion
}

Fix

Wait on the started thread with join(), or use an ExecutorService that manages the lifecycle.