Java并发Futures和Callables类

//submit the callable using ThreadExecutor
//and get the result as a Future object
Future result10 = executor.submit(new FactorialService(10));

//get the result using get method of the Future object
//get method waits till the thread execution and then return the result of the execution.
Long factorial10 = result10.get();
Java

实例
以下TestThread程序显示了基于线程的环境中Futures和Callables的使用。
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class TestThread {

public static void main(final String[] arguments) throws InterruptedException, ExecutionException {
ExecutorService executor = Executors.newSingleThreadExecutor();

  System.out.println("Factorial Service called for 10!");
  Future<Long> result10 = executor.submit(new FactorialService(10));

  System.out.println("Factorial Service called for 20!");
  Future<Long> result20 = executor.submit(new FactorialService(20));

  Long factorial10 = result10.get();
  System.out.println("10! = " + factorial10);

  Long factorial20 = result20.get();
  System.out.println("20! = " + factorial20);

  executor.shutdown();

}

static class FactorialService implements Callable{
private int number;
public FactorialService(int number) {
this.number = number;
}

  @Override
  public Long call() throws Exception {
     return factorial();
  }

  private Long factorial() throws InterruptedException{
     long result = 1; 
     while (number != 0) { 
        result = number * result; 
        number--; 
        Thread.sleep(100); 
     } 
     return result;    
  }

}
}