/**
* FutureTask
* 将一千万条数据中的数字取出并相加
*/
public class FutureTaskTest {
static List<String> list = new ArrayList<>(10000000);
public static void main(String[] args) throws Exception {
//1.生成一千万条数据
for (int i = 0, j = 10000000; i < j; i++) {
list.add("AAAA" + 2 + "ssss");
}
System.out.println("list set success");
//2.普通循环测试
long start = new Date().getTime();
long resultSum = 0;
for (int i = 0, j = 10000000; i < j; i++) {
String s = list.get(i);
String b = Pattern.compile("[^0-9]").matcher(s).replaceAll("");
Integer integer = Integer.valueOf(b);
resultSum += integer;
}
long end = new Date().getTime();
System.out.println((end - start) + "," + resultSum);
//3.futureTask测试
long start2 = new Date().getTime();
FutureTask<Long> futureTask1 = new ChildTask(0, 3333333).getFutureTask();
FutureTask<Long> futureTask2 = new ChildTask(3333333 + 1, 3333333 * 2).getFutureTask();
FutureTask<Long> futureTask3 = new ChildTask(3333333 * 2 + 1, 10000000 - 1).getFutureTask();
Long result = futureTask1.get();//获取结果,此时如果task未结束,会阻塞
Long result2 = futureTask2.get();
Long result3 = futureTask3.get();
long end2 = new Date().getTime();
System.out.println((end2 - start2) + "," + (result + result2 + result3));
}
}
//子线程
class ChildTask {
int start;
int end;
public ChildTask(int start, int end) {
this.start = start;
this.end = end;
}
public FutureTask<Long> getFutureTask() {
Callable<Long> callable = () -> {
Long result = 0L;
for (int i = start, j = end; i <= j; i++) {
String s = FutureTaskTest.list.get(i);
String b = Pattern.compile("[^0-9]").matcher(s).replaceAll("");
Integer num = Integer.valueOf(b);
result += num;
}
return result;
};
FutureTask<Long> task = new FutureTask<>(callable);
new Thread(task).start();
return task;
}
}
结果:比普通循环快3s
image.png
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