Dukansu suna ayyana ki tsara abubuwa, amma ta hanyoyi daban-daban: Comparable yana ayyana tsarin halitta na ajin (aiki da ajin kanta), yayin da Comparator yana ayyana tsarin da dabam (wani abin kansa). Zaɓin ya dogara da ko tsari yana ciki ko yafi.
public class Person implements Comparable<Person> {
private String name;
private int age;
@Override
public int compareTo(Person other) { // defines THE natural order
return Integer.compare(this.age, other.age); // by age
}
// return: negative if this < other, 0 if equal, positive if this > other
}
List<Person> people = ...;
Collections.sort(people); // uses compareTo — sorts by age (the natural order)
Comparable yana zaune ciki na ajin ta compareTo(), ayyana tsarinta gida ɗaya. Ana amfani dashi ta atomatik ta Collections.sort, TreeSet, TreeMap, da sauransu.
// define orderings OUTSIDE the class — as many as you need
Comparator<Person> byName = (a, b) -> a.getName().compareTo(b.getName());
Comparator<Person> byAge = Comparator.comparingInt(Person::getAge);
people.sort(byName); // sort by name
people.sort(byAge.reversed()); // by age, descending
Comparator wani abin kansa ne, yana baki ka ayyana da yawa daban-daban tsari ga ajin gida babu canja shi.
Comparator<Person> comp = Comparator
.comparing(Person::getLastName) // primary: last name
.thenComparing(Person::getFirstName) // tie-break: first name
.thenComparingInt(Person::getAge) // then: age
.reversed(); // reverse the whole thing
people.sort(comp);
Hanyar gida comparing/thenComparing abubuwan gida na sauran koli sauri kankanta. Yi tajalla da kankanta.
Comparable → the class has ONE obvious natural order (numbers by value, strings
alphabetically, dates chronologically); you own the class
Comparator → you need MULTIPLE orderings, situational/custom ordering, OR you
can't modify the class (e.g. sorting a third-party type differently)
Tsari abubuwa yana bukatun komi - tsara listin, amfani da TreeSet/TreeMap, nemo mafi kankanta/mafi girma.
Ancewa bambancin Comparable-vs-Comparator ya bai ka zaɓi daidai: Comparable don tsarin kamata na ajin (gida, amfani da atomatik), Comparator don jiyya da yawa ko tsarin waje (tsara bayanan gida ta fannonin daban-daban, ko tsara nau'ikan ba zaka damje ba).
API na Comparator na zamani mai hawaye (comparing/thenComparing/reversed) yana sanya tsari masu matakan canji lafiya.
Masoyi a duka biyu — da menene kowa ya dace — ya zama mahimman aiki da tsarin bayanan waje da abubuwan jiya a cikin Java.