Java – bad practice – the class defines CompareTo (…) and uses object equals()

Want to know what needs to be done with the listed methods

public final int compareTo(final FieldDTO o) {
        return o.available.compareTo(this.available);

It throws an exception on line 2. Bad practice - the class defines CompareTo (...) and uses object Equals() 16 days field defines CompareTo (fielddto) and uses object equals()

I don't know what I should do Thank you in advance

Solution

If you define CompareTo, you should at least define equals

boolean equals(it) { 
  return compareTo(it) == 0; 
}

When you put objects in maps and collections, you will encounter strange problems It is also generally good practice to define hashcode