转自 http://auguslee.iteye.com/blog/1292335
Callable 和 Runnable 的使用方法大同小异, 区别在于:
1.Callable 使用 call() 方法, Runnable 使用 run() 方法
2.call() 可以返回值, 而 run()方法不能返回。
3.call() 可以抛出受检查的异常,比如ClassNotFoundException, 而run()不能抛出受检查的异常。
Callable示例如下:
- class TaskWithResult implements Callable<String> {
- private int id;
- public TaskWithResult(int id) {
- this.id = id;
- }
- @Override
- public String call() throws Exception {
- return "result of TaskWithResult " + id;
- }
- }
- public class CallableTest {
- public static void main(String[] args) throws InterruptedException,
- ExecutionException {
- ExecutorService exec = Executors.newCachedThreadPool();
- ArrayList<Future<String>> results = new ArrayList<Future<String>>(); //Future 相当于是用来存放Executor执行的结果的一种容器
- for (int i = 0; i < 10; i++) {
- results.add(exec.submit(new TaskWithResult(i)));
- }
- for (Future<String> fs : results) {
- if (fs.isDone()) {
- System.out.println(fs.get());
- } else {
- System.out.println("Future result is not yet complete");
- }
- }
- exec.shutdown();
- }
- }
执行结果
- result of TaskWithResult 0
- result of TaskWithResult 1
- result of TaskWithResult 2
- result of TaskWithResult 3
- result of TaskWithResult 4
- result of TaskWithResult 5
- result of TaskWithResult 6
- result of TaskWithResult 7
- result of TaskWithResult 8
- result of TaskWithResult 9
Runnable示例:
- public class LiftOff implements Runnable {
- protected int countDown = 10;
- private static int taskCount = 0;
- private final int id = taskCount++;
- public LiftOff() {
- }
- public LiftOff(int countDown) {
- this.countDown = countDown;
- }
- public String status() {
- return "#" + id + "(" + (countDown > 0 ? countDown : "LiftOff! ") + ")";
- }
- @Override
- public void run() {
- while (countDown-- > 0) {
- System.out.print(status());
- Thread.yield();
- }
- System.out.println();
- }
- public static void main(String[] args) {
- ExecutorService exec = Executors.newFixedThreadPool(1);
- for (int i = 0; i < 5; i++) {
- exec.execute(new LiftOff());
- }
- exec.shutdown();
- }
- }
执行结果
- #0(9)#0(8)#0(7)#0(6)#0(5)#0(4)#0(3)#0(2)#0(1)#0(LiftOff! )
- #1(9)#1(8)#1(7)#1(6)#1(5)#1(4)#1(3)#1(2)#1(1)#1(LiftOff! )
- #2(9)#2(8)#2(7)#2(6)#2(5)#2(4)#2(3)#2(2)#2(1)#2(LiftOff! )
- #3(9)#3(8)#3(7)#3(6)#3(5)#3(4)#3(3)#3(2)#3(1)#3(LiftOff! )
- #4(9)#4(8)#4(7)#4(6)#4(5)#4(4)#4(3)#4(2)#4(1)#4(LiftOff! )
注意ExecutorService 在Callable中使用的是submit(), 在Runnable中使用的是 execute()