Use string in switch case in java

Question

I need to change the following if\'s to a switch-case while checking for a String, to improve the cyclomatic complexity.<

Answer 1

Here is a possible pre-1.7 way, which I can't recommend:

public class PoorSwitch
{
    final static public int poorHash (String s) {
        long l = 0L;
        for (char c: s.toCharArray ()) {
            l = 97*l + c;
        }
        return (int) l;
    }

    public static void main (String args[])
    {
        String param = "foo";
        if (args.length == 1)
        {
            param = args[0];
        }
        // uncomment these lines, to evaluate your hash
        // test ("foo");
        // test ("bar");
        switch (poorHash (param)) {
            // this doesn't work, since you need a literal constant
            // so we have to evaluate our hash beforehand:
            // case poorHash ("foo"): {
            case 970596: {
                System.out.println ("Foo!");
                break;
            }
            // case poorHash ("bar"): {
            case 931605: {
                System.out.println ("Bar!");
                break;
            }
            default: {
                System.out.println ("unknown\t" + param);
                break;
            }
        }
    }

    public static void test (String s)
    {
        System.out.println ("Hash:\t " + s + " =\t" + poorHash (s));
    }
}

Maybe you could work with such a trick in a generated code. Else I can't recommend it. Not so much that the possibility of a hash collision makes me worry, but if something is mixed up (cut and paste), it is hard to find the error. 931605 is not a good documentation.

Take it just as proof of concept, as curiosity.