What synchronization mechanisms can ensure the correct order of thread awakening?

To ensure the correct order of thread wake-up in Android (and in Java in general), the following synchronization mechanisms can be used:

• Monitors and wait()/notify()/notifyAll() methods — allow one thread to wait for a certain condition, while another notifies about its occurrence. It is important to use notify() or notifyAll() inside a synchronized block.

• Semaphores — limit the number of threads that can execute a certain section of code simultaneously and manage their wake-up order.

• CountDownLatch — allows one or several threads to wait until other threads perform a certain action.

• Condition from java.util.concurrent.locks — a more flexible mechanism for waiting and notification, allowing control over the wake-up order.

Example using wait/notify for ordered wake-up:

synchronized(lock) {
    while (!condition) {
        lock.wait(); // thread waits
    }
    // execution after wake-up
}

// In another thread
synchronized(lock) {
    condition = true;
    lock.notify(); // wake up one thread
}