Converting Integers to Roman Numerals - Java

This is a homework assignment I am having trouble with.

I need to make an integer to Roman Numeral converter using a method. Later, I must then use the program to write out 1 to 3999 in Roman numerals, so hardcoding is out. My code below is very bare-bones; it is a basic I/O loop with a way to exit while using a package for getIntegerFromUser we made in class.

Is there a way to assign values to Strings and then add them together when I call the method?

Update: I got some pseudo code from my professor to help me, and while I understand what he is trying to say, I am having some trouble with the ifs. Will I be needing many, many if statements so that my converter will correctly handle the Roman numeral formatting or is there a manner in which I can do this with more efficiency? I've updated my code to reflect my placeholder method.

Update (Oct 28 2012): I got it working. Here's what I ended up using:

public static String IntegerToRomanNumeral(int input) {
    if (input < 1 || input > 3999)
        return "Invalid Roman Number Value";
    String s = "";
    while (input >= 1000) {
        s += "M";
        input -= 1000;        }
    while (input >= 900) {
        s += "CM";
        input -= 900;
    }
    while (input >= 500) {
        s += "D";
        input -= 500;
    }
    while (input >= 400) {
        s += "CD";
        input -= 400;
    }
    while (input >= 100) {
        s += "C";
        input -= 100;
    }
    while (input >= 90) {
        s += "XC";
        input -= 90;
    }
    while (input >= 50) {
        s += "L";
        input -= 50;
    }
    while (input >= 40) {
        s += "XL";
        input -= 40;
    }
    while (input >= 10) {
        s += "X";
        input -= 10;
    }
    while (input >= 9) {
        s += "IX";
        input -= 9;
    }
    while (input >= 5) {
        s += "V"