用线程来解决性能问题(打印10000000以内的素数)

引用

package com.java.day01;

import java.util.ArrayList;
import java.util.List;

public class Zhishu {

	public static void zhiShu(int end, int fen) {
		class Run implements Runnable {
			int start;
			int end;
			public void run() {
				outer : for (int i = start; i <= end; i++) {
					for (int j = 2; j < Math.sqrt(i) + 1; j++) {//减少循环次数；
						if (i % j == 0) {
							continue outer;
						}
					}
					System.out.println(i);
				}
			}
		}
		// 把得到的素数，分N个放到list集合当中然后循环打印；
		List<Run> list = new ArrayList<Run>();
		int size = end / fen;
		for (int i = 0; i < fen; i++) {
			int e = i * size;
			Run r = new Run();
			r.start = e;
			if (i == 0)
				r.start = 2;
			r.end = e + size - 1;
			if (i == fen - 1)
				r.end = end;
			list.add(r);
		}
		for (Run r : list) {
			new Thread(r).start();
		}

	}
	public static void main(String[] args) {
		zhiShu(10000000, 20);
	}

}