函数执行的顺序（多线程）

Question

I'm using Java.

I have a main function and function f(). Thread is created in f(), but it takes more time that other operations in f(). What is the true order of the сapital letters?

main() {
  operations A;
  f();
  operations B;
}

f() {
  C;
  final Thread thread = new Thread() {
        @Override
        public void run() {
          many operations, more than B+D;
          E;
        }
  };
  thread.start();
  D;
}

How would I make sure that order is ACDBE?

Answer 1

You use a condition variable to ensure some code won't run before notified. Assuming the whole procedure is run only once,

volatile boolean canGoOn = false;
final Object condition = new Object();

// in main:
B;
synchronized (condition) {
    canGoOn = true;
    condition.notify();
}

// in thread:
synchronized (condition) {
    while (!canGoOn) {
        condition.wait();
    }
}
E;

(Not tested, you may need to catch some InterruptedException.)

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BTW If you are using Android this whole idiom is packaged into the android.os.ConditionVariable class, which you just need to .open() it in main and .block() it in thread.