roman to integer

public class Solution{
	public int romanToInt(String s){
		int nums[] = new int[s.length()];
		int sum = 0;
		for(int i = 0 ; i < s.length() ; i++){
			switch(s.charAt(i)){
				case 'I':
					nums[i] = 1;
					break;
				case 'V':
					nums[i] = 5;
					break;
				case 'X':
					nums[i] = 10;
					break;
				case 'L':
					nums[i] = 50;
					break;
				case 'C':
					nums[i] = 100;
					break;
				case 'D':
					nums[i] = 500;
					break;
				case 'M':
					nums[i] = 1000;
					break;
			}
		}
		for(int i = 0 ; i < s.length() - 1 ; i++){
			if(nums[i] < nums[i+1]){
				sum -= nums[i];
			}else{
				sum += nums[i];
			}
		}
		return sum + nums[s.length() - 1];
		
	}
}