JavaFX Character Comparator für TableColumn

[Cappuccino90]

Hi, habt ihr eine Idee warum folgender Comparator nicht geht?

Beispiel Character:{'g','c','null','b','null','a'}

package de.hhn.pp.todomanager.model;

import java.util.Comparator;

public class NullComparator implements Comparator<Character> {

    @Override
    public final int compare(final Character o1, final Character o2) {

        if (o1 == null && o2 == null) {
            System.out.println("If1");
            return 0;
        }

        if (o1 == null) {
            System.out.println("If2");
            return 1;
        }

        if (o2 == null) {
            System.out.println("If3");
            return -1;
        }
        System.out.println("passed the ifs");

        return o1.compareTo(o2);
    }
}

MainViewController.java

TableColumn<TaskControl, Character> colPrioritaet;
private TableView<TaskControl> tblView;


colPrioritaet
                .setCellValueFactory(new PropertyValueFactory<>("priority"));
        colPrioritaet.setComparator(new NullComparator());

TaskControl.java

private char priority;