String oneLeft(String s) { }

private static final Map<Character, Character> LEFT_KEYS = new HashMap<Character, Character>() {{
    put('v', 'c');
    put('w', 'q');
    // etc for all keys that have keys to the left
}};

char key; // read from wherever
Character left = LEFT_KEYS.get(key); // could be null

public static void main (String[] args) {
    Scanner input = new Scanner(System.in);
    String key = input.next();
    System.out.println(getOneLeftOf(key));
    input.close();
}

private static char getOneLeftOf(String key) {
    String kbd1 = "qwertyuiop[]\";
    String kbd2 = "asdfghjkl;'";
    String kbd3 = "zxcvbnm,./";
    int keyPosition;
    char nextToKey = ' ';

    if (kbd1.contains(key)) {
        keyPosition = kbd1.indexOf(key)-1;
        nextToKey = kbd1.charAt(keyPosition);

    } else if (kbd2.contains(key)) {
        keyPosition = kbd2.indexOf(key)-1;
        nextToKey = kbd2.charAt(keyPosition);

    } else if (kbd3.contains(key)) {
        keyPosition = kbd3.indexOf(key)-1;
        nextToKey = kbd3.charAt(keyPosition);

    } else {
        System.out.println("Key not found");
    }

    return nextToKey;
}

public class DickTracyRing {

    public static void main(String[] args) {
        char[] encoder=new char['z'+1];
        fill(encoder, "qwertyuiop");
        fill(encoder, "asdfghjkl");
        fill(encoder, "zxcvbnm");
        System.out.println(encode("my message", encoder));
    }

    private static String encode(String str, char[] lookup) {
        char[] text=str.toCharArray();
        for (int i=0; i<text.length; i++) {
            if (text[i]>='a' && text[i]<='z') text[i]=lookup[text[i]];
        }
        return new String(text);
    }

    private static void fill(char[] lookup, String row) {
        char[] crow = row.toCharArray();
        for (int i = 0; i < crow.length; i++) {
            lookup[crow[i]] = crow[(crow.length-1+i)%crow.length];
        }
    }
}

public static char oneLeft (char s)
{
    // note the wrap-around chars ('p', 'l', 'm')
    final String keyboard = "pqwertyuioplasdfghjklmzxcvbnm";

    // use lastIndexOf to not conflict with wrap-around chars
    int index = keyboard.lastIndexOf(s);

    return (index > 0) ? keyboard.charAt(index - 1) : s;
}

System.out.println(oneLeft('v')); // prints c
System.out.println(oneLeft('z')); // prints m
System.out.println(oneLeft('9')); // prints 9

System.out.println(oneLeft('P')); // prints P

static String[] lowercaseKeyboard = new String[] {
    "`1234567890-=",
    "tqwertyuiop[]\",
    "asdfghjkl;'n",
    "zxcvbnm,./"
};

private static char oneLeft(char c) {
    for(String s : lowercaseKeyboard) {
        int index = s.indexOf(c);

        if(index>0)
            return s.charAt(index-1);
        else if(index == 0)
            throw new InternalError("there is no char to the left of this");
    }

    throw new InternalError("char entered is not on keyboard");
}

oneLeft('s') == 'a'
oneLeft('y') == 't'
oneLeft('c') == 'x'
oneLeft('j') == 'h'
oneLeft(']') == '['