The text below comes from Comparator vs Comparable Comparable A comparable object is capable of comparing itself with another object. The class itself must implements the java.lang.Comparable interface in order to be able to compare its instances. Comparator A comparator object is capable of comparing two different objects. The class is not comparing its instances, … Read more
When your class implements Comparable, the compareTo method of the class is defining the “natural” ordering of that object. That method is contractually obligated (though not demanded) to be in line with other methods on that object, such as a 0 should always be returned for objects when the .equals() comparisons return true. A Comparator … Read more
There are a couple of awkward things with your example class: it’s called People while it has a price and info (more something for objects, not people); when naming a class as a plural of something, it suggests it is an abstraction of more than one thing. Anyway, here’s a demo of how to use … Read more
Your comparator is not transitive. Let A be the parent of B, and B be the parent of C. Since A > B and B > C, then it must be the case that A > C. However, if your comparator is invoked on A and C, it would return zero, meaning A == C. … Read more
Since Date implements Comparable, it has a compareTo method just like String does. So your custom Comparator could look like this: public class CustomComparator implements Comparator<MyObject> { @Override public int compare(MyObject o1, MyObject o2) { return o1.getStartDate().compareTo(o2.getStartDate()); } } The compare() method must return an int, so you couldn’t directly return a boolean like you … Read more