java版求100以内的素数

java版求100以内的素数

package com.sjzmlb.test;
public class TestPrimeTime {
	
	public static void main(String[] args) {
		long start = System.nanoTime();
//		method1();
		method2();
		long end = System.nanoTime();
		System.out.println(end - start);
	}
	
	public static void method1() {
		int i,j,k;
		for(i = 1;i < 101;i++){
			k = (int)Math.sqrt(i);
			for(j = 2;j <= k;j++){
				if(i % j == 0){
					break;
				}
			}
			if(j > k){
				System.out.println(i);
			}
		}
	}
	
	public static void method2() {
		int i,j;
		int[] a = new int[101];
		for(i = 1;i < 101;i++){
			a[i] = 1;
		}
		for(i = 2;i < 101;i++){
			if(a[i] != 0){
				for(j = i + i;j < 101;){
					if(j % i == 0){
						a[j] = 0;
					}
					j = j + i;
				}
			}
		}
		for(i = 2;i < 101;i++){
			if(a[i] != 0){
				System.out.println(i);
			}
		}
	}
}