Substitute for "synchronized" keyword in Java for multithreading

can you check if this code will be thread safe/ replace synchronization's features? like restricting access to multiple threads?

class CheckSynch{

  public static booloean check=true;

  public static void func() // I am trying to write alternative code for synchronized function
  {
     if(check) 开发者_如何学Python{
       check=false;
       //body of function
       check=true;
       notifyAll();
     } else {
       wait();
     }
  }
}

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Anything that doesn't use proper synchronization is bound to break. If you have two hardware threads, they will run concurrently, so in the time between check being checked and modified, a different thread could have come along and changed it.

I don't know why you're trying to shun synchronized, but whatever you're trying to do with unsynchronized functions, it won't work and will eventually break in very hard-to-reproduce bugs.

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Writing your own Locking/sychronizaton is very advanced topic, writing code which compiles is not an advanced topic. You have to ask yourself if this really is a good idea.

You can write something like

final Lock lock = new ReentrantLock();

public static void func() {
    lock.lock();
    try {
       //body of function
    } finally {
       lock.unlock();
    }
}

However, you haven't said WHY you want to write you own synchronisation. I assume it because you don't want to wait 1-2 micro-seconds it takes to acquire a lock.

You can instead use a busy loop.

final AtomicBoolean lock = new AtomicBoolean();

public static void func() {
    // wait for the lock to be false and set it to true.
    while(lock.getAndSet(true)); 
    try {
        // body of function
    } finally {
        lock.set(false);
    }
}

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no, wait() needs to be in a synchronized block.

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Its always advisable to avoid the synchronized block in a static method.

i agree with EboMike, although if you are looking to block threads based on read/write criteria.. you can always use the ReentrantReadWriteLock