Someone

static int[] a = new int[100];
	static int index = 3;
	static
	{
		a[0]=2;
		a[1]=3;
		a[2]=5;
		a[3]=7;
	}

	public int nextPrime(int n)
	{
		//creat an arry.
		//divide the number with all the prime numbers you have so far. 
		//if none of them results in a reminder of zero,
		//then the number must be prime.
		//you add this new prime number to the collection of primes you have so far. 
		//then return the prime number
		
		while(true)
		{
			for(int i=0; i<a.length ; i++)
			{
				if(n%a[i]!=0)
					a[index+1]=n;
					
				
				else
					n=n+1;
			}
			
			return index;
		}
	
	}