等待变量更改其值的最佳方法 [英] Best way to wait until a variable changes its value

问题描述

我意识到我要问的不是特定的Codename One问题，而是通用的Java问题，无论如何，考虑到参考API是Codename One的问题，是否有一种更优雅，更可靠的方式来处理情况像下面的代码?如果我需要同步制作本质上与回调异步的代码，则会发生这种情况:

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));
}

我在这里引用了这样的代码: https://github.com/codenameone/CodenameOne/issues/3192

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

推荐答案

JavaSE具有一些很酷的功能，但我们目前不支持它们，例如 CountDownLatch .

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

但这仍然很容易做到:

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;
    }
}

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