JFugue note changing not working properly

I'm trying to transpose a note, but the result it returns is not what it should be. Could you please check my code and tell me where I am wrong?

public int changeTone(String chord) {
            int changeTone = 0;
            switch(chord) {
            case "I":
            changeTone = 0;
            break;
        case "II":
            changeTone = 1;
            break;
        case "III":
            changeTone = 2;
            break;
        case "IV":
            changeTone = 3;
            break;
        case "V":
            changeTone = 4;
            break;
        case "VI":
            changeTone = 5;
            break;
        case "VII":
            changeTone = 6;
            break;
        case "i":
            changeTone = 0;
            break;
        case "ii":
            changeTone = 2;
            break;
        case "iii":
            changeTone = 4;
            break;
        case "iv":
            changeTone = 5;
            break;
        case "v":
            canviDeTo = 7;
            break;
        case "vi":
            changeTone = 9;
            break;
        case "vii":
            changeTone = 11;
            break;
        default:
            System.out.println("Vaya"); 
            break;

        }
        return changeTone ;
    }

public String getChord(int interval) {
    String chord = "";

    switch(interval) {
            case "0":
                chord = "C";
                break;
            case "2":
                chord = "D";
                break;
            case "4":
                chord = "E";
                break;
            case "5":
                chord = "F";
                break;
            case "7":
                chord = "G";
                break;
            case "9":
                chord = "A";
                break;
            case "11":
                chord = "B";
}
return chord;
}

public String WriteChord(String chords, String tone) {
    String finalChord;
    String[] chordArray = chords.split("-");
    for(int i=0; i < chordArray.length; i++){
        String chord = chordArray[i];
        int interval = changeTone(chord);
        chord = getChord(interval);
        Note note = new Note(chord);
        finalChord += note.changeValue(interval).toString() += "-";
    }
return finalChord;

}

OK, so what this tries to do is to change the value of a chord given a chord progession with intervals. Like I-III-IV-iv. The user would choose a tone (the tonical, I note) and the chord would be changed taking the note as a reference. So, for example, running the code should do the following:

The user chooses a tone, say "E".
The code generates a chord progression, say "I-III-IV-iv".
The code gets the interval between I and III, I and IV, and I and iv.
The initial note, "E", changes its value with the interval.

The expected output is: E-G#-A#-A# The actual output is: C-G#-G#-Bb

Why doesn't this work? I have simplified my code, so if you need a bit more let me know! Thanks in advance.

Edit: I have corrected the code and added the expected/gotten output.

JFugue already has support for intervals and chord progressions. I hope the following code satisfies your needs:

import org.jfugue.theory.ChordProgression;

public static void main(String[] args) {
    ChordProgression cp = new ChordProgression("I-III-IV-iv").setKey("E");
    System.out.println(cp);
}

The output from this code is:

E4MAJ G#4MAJ A4MAJ A4MIN

You can play this directly in a Player:

Player player = new Player();  // Don't forget to import org.jfugue.player.Player
player.play(cp);

If that's playing a little too fast for you because of the default duration of a quarter note, you can play each chord as something longer, say a whole note: