What does it mean by saying "Comparable affects the original class, but Comparator doesnt"
// Original class Dog
class Dog{
String name;
int age;
}
//Case 1
class Dog implements Comparable<Dog>{
//compareTo() implementation
}
//Case2
class Dog implements Comparator<Dog>{
// compare() implementation
}
//Case 3
class DogNameComparator implements Comparator<Dog>{
// compare() implementation
}
Collection.sort(dogList);
Collectios.sort(dogList,new DogNameComparator());
Collection.sort(dogList,new Dog());
Isn't it true that in case 2 the original class is actually modified, even though they say the Comparator does not modify the original class?
Maybe if I didn't understand the concept correctly, enlighten me on it.
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Comparable
can only be implemented in the original class, so there can only be one implementation for it (unless you override compareTo
with a subclass). Meanwhile, it Comparator
doesn't need to be implemented in the original class, so there can be many implementations.
The second case is very different from the first case, as it compare
will have access to three instances Dog
( this
, parameter # 1 and parameter # 2), while it compareTo
will have access to two instances Dog
( this
and parameter # 1).
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