Random Word Generator

package de.randomletter.main;

public class Main {

    private static int random;
    private static int times = 5;
    private static int words = 5;
    private static String letter = "", sLetter = "";

    public static void main(String[] args)
    {
        execute();
    }

    public static void execute()
    {
        for(int j=1; j<=words; j++){
        for(int i=1; i<=times; i++)
        {
            random = (int) (Math.random()*30)+1;
            switch(random)
            {
            case 1: letter += "a"; sLetter = "a"; break;
            case 2: letter += "b"; sLetter = "b"; break;
            case 3: letter += "c"; sLetter = "c"; break;
            case 4: letter += "d"; sLetter = "d"; break;
            case 5: letter += "e"; sLetter = "e"; break;
            case 6: letter += "f"; sLetter = "f"; break;
            case 7: letter += "g"; sLetter = "g"; break;
            case 8: letter += "h"; sLetter = "h"; break;
            case 9: letter += "i"; sLetter = "i"; break;
            case 10: letter += "j"; sLetter = "j"; break;
            case 11: letter += "k"; sLetter = "k"; break;
            case 12: letter += "l"; sLetter = "l"; break;
            case 13: letter += "m"; sLetter = "m"; break;
            case 14: letter += "n"; sLetter = "n"; break;
            case 15: letter += "o"; sLetter = "o"; break;
            case 16: letter += "p"; sLetter = "p"; break;
            case 17: letter += "q"; sLetter = "q"; break;
            case 18: letter += "r"; sLetter = "r"; break;
            case 19: letter += "s"; sLetter = "s"; break;
            case 20: letter += "t"; sLetter = "t"; break;
            case 21: letter += "u"; sLetter = "u"; break;
            case 22: letter += "v"; sLetter = "v"; break;
            case 23: letter += "w"; sLetter = "w"; break;
            case 24: letter += "x"; sLetter = "x"; break;
            case 25: letter += "y"; sLetter = "y"; break;
            case 26: letter += "z"; sLetter = "z"; break;
            case 27: letter += " "; sLetter = " "; break;
            case 28: letter += "ö"; sLetter = " "; break;
            case 29: letter += "ä"; sLetter = " "; break;
            case 30: letter += "ü"; sLetter = " "; break;
            }
            //System.out.println("[" + i + "]: " + random + ", " + sLetter + ", " + letter);
        }
        System.out.println("[Word " + j + "]: " + letter);
        letter = "";
        sLetter = "";
        }
    }

}