算法-輸出英文字母對應的數字

問題描述：
如輸入數字a~z， 輸出數字1~26
輸入數字ab，輸出28

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class To26 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        String src = ""; int target = 0;
        while(input.hasNextLine()){
            src = input.nextLine();
            target = tranform(src);
        }
    }

    public static int tranform(String str){
        String[] nums = {"a", "b","c", "d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        Map<String, Integer> numMap = new HashMap<String, Integer>(); int result = 0; int length = str.length();
        if(str.length()<0 || "".equals(str)){
            System.out.println("ERROR");
            return -1;
        }
        for(int i = 0; i<nums.length; i++){
            numMap.put(nums[i], i);
        }

        if(str.length()==1){
            if(" ".equals(str)){
                System.out.println("Error");
                return -1;
            }
             //System.out.println("Error");
             result = numMap.get(str) + 1;

        }else{
            int tempLength = length;
            for(int i = 0; i < length; i++){
                char ch = str.charAt(i);
                int location = numMap.get(String.valueOf(ch));
                result += (location + 1) * 26 * (tempLength - 1);
                tempLength = tempLength - 1 ;
            }
            char ch = str.charAt(length-1);

            int temp = numMap.get(String.valueOf(ch)) + 1;
            //result = (length - 1)*26 + temp;
            result = result + temp;
        }
        System.out.println(result);

        return result;

    }

}