import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class SimplePriorities implements Runnable {

  private int countDown = 5;

  /*Java語言規(guī)范第三版中對volatile的定義如下： java編程語言允許線程訪問共享變量，
  為了確保共享變量能被準(zhǔn)確和一致的更新，線程應(yīng)該確保通過排他鎖單獨(dú)獲得這個變量。
  Java語言提供了volatile，在某些情況下比鎖更加方便。如果一個字段被聲明成volatile，
  java線程內(nèi)存模型確保所有線程看到這個變量的值是一致的。*/
  private volatile double d;
  private int priority;

  public SimplePriorities(int priority){
    this.priority = priority;
  }

  public String toString(){
    //獲取當(dāng)前線程信息
    return Thread.currentThread() + ":" + countDown;
  }

  @Override
  public void run() {
    //設(shè)置線程優(yōu)先級 1-10
    Thread.currentThread().setPriority(priority);

    while(true){

      for(int i = 0;i<100000;i++){
        d += (Math.PI + Math.E) / (double)i;
        if(i00 == 0){
          Thread.yield();
        }
      }
      System.out.println(this.toString());

      if(--countDown == 0)return;

    }

  }

  public static void main(String[] args) {


    ExecutorService exec = Executors.newCachedThreadPool();

    //優(yōu)先級為1
    exec.execute(new SimplePriorities(Thread.MIN_PRIORITY));
    //優(yōu)先級為10
    exec.execute(new SimplePriorities(Thread.MAX_PRIORITY));

    exec.shutdown();
  }

}