natasa.java

/*
    Aufgabe 4) Rekursion mit Strings
*/
public class Aufgabe4 {

    private static String insertCharValue(String text) {
        String a = "";
        int decimalASCII = text.charAt(0);
        if (text.length() == 1) {
            a = a + '(';
            a = a + decimalASCII;
            a = a + text.charAt(0);
            a = a + ')';
           return a;
        } else {
            a = a + '(';
            a = a + decimalASCII;
            a = a + text.charAt(0);
            a = a + ')';
            return (a + insertCharValue(text.substring(1)));
        }
    }

    private static String removeCharsInString(String text) {
        String pos = text.substring(1);
        int pos2 = pos.indexOf(text.charAt(0));
       // int position = text.substring(1).indexOf(text.charAt(0)); // first char in String
        if (pos2 > 0) { //if char is valid aka char > 0
            return removeCharsInString(text.substring(0, pos2 + 1) + text.substring(pos2 + 2));
        }
        return text.substring(1);
    }

    private static String shiftMaxCharRight(String text) {
        if (text.length() == 0) {
            return "";
        }
        if (text.length() == 1) {
            return text;
        } else {
            if (text.charAt(0) > shiftMaxCharRight(text.substring(1)).charAt(text.length() - 2)) {
                return (text.substring(1) + text.charAt(0));
            }
            else {
                return (text.charAt(0) + shiftMaxCharRight(text.substring(1)));
            }

        }
    }

    public static void main(String[] args) {
        System.out.println(insertCharValue("hallo"));
        System.out.println(insertCharValue("a!"));
        System.out.println(insertCharValue("Ein Test"));
        System.out.println();

        System.out.println(removeCharsInString("testtrompete"));
        System.out.println(removeCharsInString("test"));
        System.out.println(removeCharsInString("t"));
        System.out.println(removeCharsInString("angabe"));
        System.out.println();

        System.out.println(shiftMaxCharRight("acmbwxdzfjdk"));
        System.out.println(shiftMaxCharRight(""));
        System.out.println(shiftMaxCharRight("za"));
        System.out.println(shiftMaxCharRight("a"));
        System.out.println(shiftMaxCharRight("habcdefg"));

        assert (insertCharValue("hallo").equals("(104h)(97a)(108l)(108l)(111o)"));
        assert (insertCharValue("a!").equals("(97a)(33!)"));
        assert (insertCharValue("Ein Test").equals("(69E)(105i)(110n)(32 )(84T)(101e)(115s)(116t)"));

        assert (removeCharsInString("testtrompete").equals("esrompee"));
        assert (removeCharsInString("test").equals("es"));
        assert (removeCharsInString("t").equals(""));
        assert (removeCharsInString("angabe").equals("ngbe"));

        assert (shiftMaxCharRight("acmbwxdzfjdk").equals("acmbwxdfjdkz"));
        assert (shiftMaxCharRight("").equals(""));
        assert (shiftMaxCharRight("za").equals("az"));
        assert (shiftMaxCharRight("a").equals("a"));
        assert (shiftMaxCharRight("habcdefg").equals("abcdefgh"));
    }
}