判断素数的最高效方法

package com.gxnu.study.primer;

public class  {
	public static void main(String[] args) {
		FilterPrime fp = new FilterPrime();
		
		long two = System.nanoTime();
		fp.prime2(357);
		System.out.println("+-的时间:"+(System.nanoTime()-two));		
		long one = System.nanoTime();
		fp.prime(357);
		System.out.println("%的时间:"+(System.nanoTime()-one));
		
	}

	public void prime2(int num){
		if (num<2) {
			System.out.println("输入的数据不合法！");
			return;
		}
		
		int arr[] = new int[num+1];
		
		for (int i = 0; i < arr.length; i++) {
			arr[i] = i;
		}
		
		for (int i = 2; i < arr.length-1; i++) {
			while(arr[i]==0){
				i++;
			}
			for (int j = i+i; j < arr.length; j+=i) {
				arr[j] = 0;
			}
			
			if (arr[num]==0) {
				break;
			}
			
			
		}
		
		if (arr[num]==0) {
			System.out.println(num+" 是合数");
		}else {
			System.out.println(num+" 是素数");
		}
		
	}
	
	
	public void prime(int num) {
		if (num<2) {
			System.out.println("输入的数据不合法！");
			return;
		}

		int arr[] = new int[num+1];

		for (int i = 0; i < arr.length; i++) {
			
			arr[i] = i;
		}
		
		


		for (int j = 2; j < arr.length-1; j++) {
			
			while(arr[j]==0){
				j++;
			}
			
			for (int k = j+1; k < arr.length; k++) {
				if ((arr[k] % j) == 0) {
					arr[k] = 0;
				}
			}
			
			if (arr[num]==0) {
				break;
			}
			

			
		}
		
		if (arr[num]==0) {
			System.out.println(num+"  是合数");
		}else {
			System.out.println(num+"  是素数");
		}
		
	}
	
}