Java Advanced-Multithreading (3)

1. The previous use of the threading API did not return the results, and Callable/future/futuretask was the solution to the problem, and in the process of calling

Make a capture of the exception

-callable executes the call () method to return an object or throw an exception;
callable is not like thread, but rather calls <T> future Executorservice.submit (callable<t> Task);
-future Returns a value that invokes the Get () method of the interface to return the corresponding object
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Salescalculatesample.java> computes the result of each row and overlays the matrix through multithreading;

/** * * @author Lean @date: 2014-9-30 */public class Salescalculatesample {private static final int number_of_month=12;p rivate static final int number_of_customer=100;private static int[][] Cells;static class Summer implements Callable<in teger>{public int customerid;public Summer (int companyid) {This.customerid=companyid;} @Overridepublic Integer Call () throws Exception {int sum=0;for (int i = 0; i < Number_of_month; i++) {Sum+=cells[custom Erid][i];} System.out.printf ("customerid:%d, sum:%d\n", customerid,sum); return sum;}} public static void Main (string[] args) {Generatematrix (); Executorservice Executor=executors.newfixedthreadpool (10); Set<future<integer>> futures=new hashset<future<integer>> (); for (int i = 0; i < NUMBER_OF_ CUSTOMER; i++) {callable<integer> caller=new Summer (i); Futures.add (Executor.submit (caller));} Caculate the Sumint sum=0;for (future<integer> future:futures) {try {sum+=future.get ();} catch (Exception e) {E . printstackTrace ();} }system.out.println ("Sum is>>" +sum); Executor.shutdown ();} private static void Generatematrix () {cells=new int[number_of_customer][number_of_month];for (int i = 0; i < number_of_ CUSTOMER; i++) {for (int j = 0; J < Number_of_month; J + +) {cells[i][j]= (int) (Math.random () *100);}}}}

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Cancancelprocessors> randomly cancels the submitted order (the futureprovides a canceled result execution )

/** * * @author Lean @date: 2014-10-7 */public class Cancancelprocessors {private static Executorservice Service=executo Rs.newfixedthreadpool (+);p rivate static final int orders_count=2000;private static Arraylist<future<integer >> futures=new arraylist<future<integer>> ();p ublic static void Main (string[] args) {for (int i = 0; I &l T;orders_count; i++) {Futures.add (Service.submit (New Orderexcutor (i))); New Thread (New Evilthread (Futures)). Start (); try {service.awaittermination (6,timeunit.seconds);} catch ( Interruptedexception e) {e.printstacktrace ();} int count=0;for (future<integer> future:futures) {if (future.iscancelled ()) {count++;}} System.out.println ("----------" +count+ "Orders canceled!---------"); Service.shutdown (); Static class Orderexcutor implements Callable<integer>{private int mid;public orderexcutor (int id) {this.mid=id;} @Overridepublic the Integer call () throws Exception {try {thread.sleep (+);} catch (Interruptedexception e) {}system.out.println ("Successfully execute OrderID:" +mid); return mId;}} Static class Evilthread implements Runnable{private arraylist<future<integer>> futures;public EvilThread ( Arraylist<future<integer>> futures) {this.futures=futures;} @Overridepublic void Run () {for (int i = 0; i < Orders_count; i++) {try {Thread.Sleep); Boolean flag=futures.get (i). Cancel (true); System.out.println ("Cancel order >" +flag + "by id>>" +i); catch (Interruptedexception e) {}}}}}

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-futuretask integrates the functions of the runnable and the future interface, so it has the function of asynchronous and returning data;
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Futuretasksample

/** * * @author Lean @date: 2014-9-30 */public class Futuretasksample {private static final int Number_of_month=12;priva Te static final int number_of_customer=100;private static int[][] Cells;static class Summer implements Callable<intege r>{public int customerid;public Summer (int companyid) {This.customerid=companyid;} @Overridepublic Integer Call () throws Exception {int sum=0;for (int i = 0; i < Number_of_month; i++) {Sum+=cells[custom Erid][i];} System.out.printf ("customerid:%d, sum:%d\n", customerid,sum); return sum;}} public static void Main (string[] args) {Generatematrix (); Set<futuretask<integer>> futures=new hashset<futuretask<integer>> (); for (int i = 0; i < Number_of_customer; i++) {callable<integer> caller=new Summer (i); futuretask<integer> futuretask=new futuretask<integer> (caller); Futuretask.run (); Futures.add ( Futuretask);} Caculate the Sumint sum=0;for (futuretask<integer> future:futures) {try {sum+=future.get ();} CATCH (Exception e) {e.printstacktrace ();}} System.out.println ("Sum is>>" +sum);} private static void Generatematrix () {cells=new int[number_of_customer][number_of_month];for (int i = 0; i < number_of_ CUSTOMER; i++) {for (int j = 0; J < Number_of_month; J + +) {cells[i][j]= (int) (Math.random () *100);}}}}

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2.Executors
. Newfixedthreadpool () Create a fixed thread pool
. Newcachedthreadpool () Create a fixed thread pool, with each thread no longer created within 60 seconds
. Newsinglethreadexecutor () creates a single thread that is not destroyed
. Newscheduledexecutorservice () Create a thread that can be timed, delayed execution
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Examples of scheduledcountsample> timing, time delay, numbers

/** *scheduledexecutorservicesample * * @author Lean @date: 2014-10-7 */public class Scheduledcountsample {private Stati C Scheduledexecutorservice Mservice=executors.newscheduledthreadpool (Ten);p rivate static final int avg=4;private  static final int mallcount=400;private static int mcurrencount=0;public static void main (string[] args) {//delay counting !//int times = mallcount/avg;//for (int i = 0; I < times; i++) {//mservice.schedule (new Trycount (i), I*1,timeunit.seco NDS);//}//mservice.scheduleatfixedrate (new Everycount (), 0, 1, timeunit.seconds); Mservice.schedulewithfixeddelay ( New Everycount (), 0, 1, timeunit.seconds);} Static class Everycount implements runnable{@Overridepublic void Run () {if (Mallcount>mcurrencount) { System.out.println ("threadid>>" +thread.currentthread (). GetId () + "and Count >>" +mcurrencount++);}}} Static class Trycount implements Callable<integer>{private int index;public trycount (int Index) {this. Index=index;} @Overridepublic Integer Call ()Throws Exception {for (int i = index*avg+0; I < (AVG+INDEX*AVG); i++) {System.out.println ("Count >>" +i);} SYSTEM.OUT.PRINTLN ("Thread Count end!"); return Index;}}}

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-executorcompletionservice
usually get results with get (), the method forms a block.and take () to get the result of a task that has ended

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Getresultrightnow

/** * Get non-blocking results * * @author Lean @date: 2014-10-7 */public class Getresultrightnow {public static void main (string[] args ) {int[] printnum={1000,200,200,30000,5000}; Arraylist<future<integer>> fetures=new arraylist<future<integer>> (); Executorservice executors = Executors.newfixedthreadpool (2); Executorcompletionservice<integer> service=new executorcompletionservice<integer> (executors); for (int I:printnum) {Fetures.add (Service.submit (New Getcurrnnum (i))); try {executors.awaittermination (5, Timeunit.seconds),} catch (Interruptedexception e) {e.printstacktrace ();} for (int i = 0; i < Printnum.length, i++) {int Num=0;try {//take It when there have a result;num = Service.take (). get (); Stop when there have no result no matter others having;//num=fetures.get (i). get (); catch (Interruptedexception e) {e.printstacktrace ();} catch (Executionexception e) {e.printstacktrace ();} SYSTEM.OUT.PRINTLN ("num is:" +num);} Executors.shutdown ();} Static Class Getcurrnnum IMplements callable<integer>{private int printnum;public getcurrnnum (int i) {printnum=i;} @Overridepublic Integer Call () throws Exception {try {thread.sleep (printnum);} catch (Exception e) {}return printnum;}}}

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Java Advanced-Multithreading (3)