submit與execute區別
阿新 • • 發佈:2020-09-08
(1)可以接受的任務型別
submit:
execute:
可以看出:
execute只能接受Runnable型別的任務
submit不管是Runnable還是Callable型別的任務都可以接受,但是Runnable返回值均為void,所以使用Future的get()獲得的還是null
(2)返回值
由Callable和Runnable的區別可知:
execute沒有返回值
submit有返回值,所以需要返回值的時候必須使用submit
(3)異常
1.execute中丟擲異常
execute中的是Runnable介面的實現,所以只能使用try、catch來捕獲CheckedException,通過實現UncaughtExceptionHande介面處理UncheckedException
即和普通執行緒的處理方式完全一致
2.submit中丟擲異常
不管提交的是Runnable還是Callable型別的任務,如果不對返回值Future呼叫get()方法,都會吃掉異常
先來看下Callable定義
public interfaceCallable<V> { V call() throws Exception; }
其中的call能夠丟擲Exception異常,所以不管是CheckedException還是UncheckedException,直接丟擲即可
import java.util.concurrent.Callable; import java.util.concurrent.ExecutionException; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; importjava.util.concurrent.Future; public class ThreadExceptionTest { public static void main(String[] args) { ExecutorService executor = Executors.newCachedThreadPool(); Future<Boolean> future = executor.submit(new CallableTask()); try { future.get(); } catch (InterruptedException e) { e.printStackTrace(); } catch (ExecutionException e) { e.printStackTrace(); } executor.shutdown();//必須不能忘,否則會一致卡在那裡 } } class CallableTask implements Callable<Boolean>{ public Boolean call() throws Exception { // InputStream in = new FileInputStream(new File("xx.pdf")); int num = 3/0; return false; } }
結果為:
java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222) at java.util.concurrent.FutureTask.get(FutureTask.java:83) at my.ThreadExceptionTest.main(ThreadExceptionTest.java:21) Caused by: java.lang.ArithmeticException: / by zero at my.CallableTask.call(ThreadExceptionTest.java:57) at my.CallableTask.call(ThreadExceptionTest.java:1) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619)
轉載:https://blog.csdn.net/cpf2016/article/details/50150205?utm_source=copy