I am trying to find a way to use these methods to save and restore a binary search tree that contains names and phone numbers in each node.

I am just very lost and how to go about doing this.

  'public void save(String fileName) {
    // TODO : implement this method.
    // save bst to its original shape.
}

public void restore(String fileName) {
    // TODO : implement this method.
    // restore bst from a file, if file exists.
    // do nothing, otherwise.
    File fichier = new File(fileName);
    if (fichier.exists()) {

    }
}'