Which method do I have to overwrite in Java to use ">" to compare instances of my class

Question

As far as I understand I can overwrite equals() in Java to handle how my class interacts with ==. Which method do I have to overwrite to be define the behavior of

MyClass obj1;
MyClass obj2;
if (obj1 > obj2){
    ...
}

Answer 1

You can't. Java doesn't support custom operator overloading. Overriding equals doesn't affect ==. The closest you can get to < is to implement the Comparable interface, which includes a compareTo method. http://docs.oracle.com/javase/7/docs/api/java/lang/Comparable.html

Answer 2

As far as I understand I can overwrite equals() in Java to handle how my class interacts with ==

This is wrong. The explanation is already covered here: How do I compare strings in Java?:

== tests for reference equality.

.equals() tests for value equality.

---

To your question:

Unlike C++ or C#, in Java you cannot overload operators.

Instead of using > and < operators you have two options.

1. Make MyClass implement Comparable:

   public MyClass implements Comparable<MyClass> {
       @Override
       public int compareTo(MyClass other) {
           //comparison logic here...
       }
   }
   

   You will use it like this:

   MyClass obj1 = ...;
   MyClass obj2 = ...;
   if (obj1.compareTo(obj2) > 0){
       ...
   }
   

2. Create a class that implements Comparator

   public class MyClassComparator implements Comparator<MyClass> {
       @Override
       public int compare(MyClass myClass1, MyClass myClass2) {
           //comparison logic here...
       }
   }
   

   You will use it like this:

   MyClass obj1 = ...;
   MyClass obj2 = ...;
   MyClassComparator comp = new MyClassComparator();
   if (comp.compare(obj1, obj2) > 0){
       ...
   }