如何在java中创建一个将输入转换为数字组合的系统

Question

I'm trying to create a system that takes a key from the user. eg 'ab'. Convert the letters into their position on the alphabet, (ab = 1, 2) and then add them together. So an example would look like.

Input: abc

Output: 6

This is what I've tried so far.

String alphabet = ("abcdefghijklmnopqrstuvwxyz");
        System.out.println("Please input a key");
        Scanner key = new Scanner(System.in);
        String keyInput = key.nextLine();



        for (int i = 0; i < keyInput.length(); i++) {
            char letter = keyInput.charAt(i);
            int[] alphLetter = new int[alphabet.indexOf(letter)];
            System.out.println(alphLetter[i]);

Answer 1

You can get a character's position in the alphabet by subtracting 'a' from it (and adding one, since you want it one-based). I think the easier approach would be to stream the characters of the string, convert them to their positions and sum them:

int result = key.chars().map(c -> c - 'a' + 1).sum();

Answer 2

It's not clear if alphabet will always be in the standard order or if it could be shuffled?

If you're just dealing with the standard alphabet you can do something simple like this:

int sum = 0;
for(int i=0; i<keyInput.length(); i++)
{
    sum += 1 + keyInput.charAt(i) - 'a';
}
System.out.println("Sum: " + sum);

If the alphabet could be shuffled you'll first need to build a map of character positions. You can use a simple array for this.

String alphabet = "mgpqrhivwxjklostufncbyzade";
int[] charPos = new int[alphabet.length()];
for(int i=0; i<alphabet.length(); i++) 
    charPos[alphabet.charAt(i)-'a'] =  i + 1;

int sum = 0;
for(int i=0; i<keyInput.length(); i++)
{
    sum += charPos[keyInput.charAt(i)-'a'];
}
System.out.println("Sum: " + sum);