submit與execute區別
(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
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public interface Callable<V> {
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V call() throws Exception;
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}
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
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import java.util.concurrent.Callable;
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import java.util.concurrent.ExecutionException;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.Future;
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public class ThreadExceptionTest {
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public static void main(String[] args) {
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ExecutorService executor = Executors.newCachedThreadPool();
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Future<Boolean> future = executor.submit(new CallableTask());
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try {
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future.get();
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} catch (InterruptedException e) {
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e.printStackTrace();
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} catch (ExecutionException e) {
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e.printStackTrace();
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}
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executor.shutdown();//必須不能忘,否則會一致卡在那裡
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}
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}
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class CallableTask implements Callable<Boolean>{
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public Boolean call() throws Exception {
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// InputStream in = new FileInputStream(new File("xx.pdf"));
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int num = 3/0;
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return false;
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}
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}
結果為:
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java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero
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at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222)
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at java.util.concurrent.FutureTask.get(FutureTask.java:83)
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at my.ThreadExceptionTest.main(ThreadExceptionTest.java:21)
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Caused by: java.lang.ArithmeticException: / by zero
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at my.CallableTask.call(ThreadExceptionTest.java:57)
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at my.CallableTask.call(ThreadExceptionTest.java:1)
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at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
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at java.util.concurrent.FutureTask.run(FutureTask.java:138)
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at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
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at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
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at java.lang.Thread.run(Thread.java:619)
--------------------- 本文來自 cpf2016 的CSDN 部落格 ,全文地址請點選:https://blog.csdn.net/cpf2016/article/details/50150205?utm_source=copy