java中的嵌套循环

Question

如我的代码所示，如​​果int x = 100，int y = 50，我必须编写50 for循环来获得结果。如何在不用Java手动输入的情况下使用递归来运行n嵌套循环？

public static void main(String[] args) {
    // create a blank arrayList to store raw data
    ArrayList < Integer > originalData = new ArrayList < > ();

    // create a blank arrayList to store all combinations
    ArrayList < ArrayList < Integer >> allCombinations = new ArrayList < > ();

    // the length of the arraylist we just created.
    // suppose it's 4 now.
    int x = 4;

    // generate elements
    for (int i = 0; i < x; i++) {
        originalData.add(i);
    }

    // how many elements we need in each combination.
    // suppoer it's 3 now
    int y = 3;

    // the number of for-loop is y
    for (int i = 0; i < originalData.size(); i++) {
        for (int j = 0; j < originalData.size(); j++) {
            for (int k = 0; k < originalData.size(); k++) {

                // create a new arrayList to store all elements in a single combination
                ArrayList < Integer > singleItem = new ArrayList < > ();
                singleItem.add(originalData.get(i));
                singleItem.add(originalData.get(j));
                singleItem.add(originalData.get(k));

                // store all combinations to an arraylist
                allCombinations.add(singleItem);

            }
        }
    }
    System.out.println(allCombinations);
}