A *wrong* code for eliminating duplicate characters from strings

gistfile1.java

    public static String deleteDuplicateCharacters(String val) {
        char[] str = val.toCharArray();
        int len = str.length;

        for (int i = 0; i < len; i++) {
            for (int j = i + 1; j < len; j++) {
                if (str[i] == str[j]) {
                    for (int k = j; k < len - 1; k++) {
                        str[k] = str[k + 1];
                    }
                    str[len - 1] = 0;
                }
            }
        }

        return new String(str).trim();
    }