Что я теперь знаю про сравнение дат. -_-

Main.java

package com.example;

import java.util.Date;

public class Main {
    public static void main(String[] args) {
        final Date source = new Date();
        final Date prev = new Date(source.getTime() - 1000);
        final Date same = new Date(source.getTime());
        final Date next = new Date(source.getTime() + 1000);
        // final Date none = null;

        System.out.println(source.compareTo(prev));
        System.out.println(source.compareTo(same));
        System.out.println(source.compareTo(next));
        // System.out.println(source.compareTo(none)); Null pointer exception.
    }
}