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Best way to wait until a variable changes its value

I realize that what I'm about to ask is more a generic Java question than a specific Codename One question, anyway, considering that the reference APIs are Codename One's, is there a more elegant and more reliable way to handle a situation like the following code? Such cases happen if I need to synchronously make code that by its nature would be asynchronous with callback:

while (lock) {
   CN.invokeAndBlock(() -> Util.sleep(500));
}

I quoted a code like that here: https://github.com/codenameone/CodenameOne/issues/3192

Solution

  • JavaSE has some pretty cool features to do that but we don't support them at this time e.g. CountDownLatch.

    But this is still pretty easy to do:

    public class SharedVar<T> {
    private T var;
    public T get() { return var; }
    public synchronized void set(T var) {
       this.var = var;
       notifyAll();
    }
    public synchronized T waitForChange() {
       wait();
       return var;
    }
}