java.util.Collections.sort() metoda je prisutna u klasi java.util.Collections. Koristi se za sortiranje elemenata prisutnih u navedenom popis zbirke uzlaznim redoslijedom. Djeluje slično kao java.util.Arrays.sort() metoda, ali je bolja nego jer može sortirati elemente niza kao i povezani red čekanja popisa i još mnogo toga prisutnog u njemu.
public static void sort(List myList)
myList : A List type object we want to sort.
This method doesn't return anything
Primjer:
Let us suppose that our list contains
{'Geeks For Geeks' 'Friends' 'Dear' 'Is' 'Superb'}
After using Collection.sort() we obtain a sorted list as
{'Dear' 'Friends' 'Geeks For Geeks' 'Is' 'Superb'}
Sortiranje ArrayList uzlaznim redoslijedom
JAVA
// Java program to demonstrate working of Collections.sort() import java.util.*; public class Collectionsorting { public static void main(String[] args) { // Create a list of strings ArrayList<String> al = new ArrayList<String>(); al.add('Geeks For Geeks'); al.add('Friends'); al.add('Dear'); al.add('Is'); al.add('Superb'); /* Collections.sort method is sorting the elements of ArrayList in ascending order. */ Collections.sort(al); // Let us print the sorted list System.out.println('List after the use of' + ' Collection.sort() :n' + al); } }
Izlaz
List after the use of Collection.sort() : [Dear Friends Geeks For Geeks Is Superb]
Vremenska složenost : O(N log N) kao vremenska složenost Collections.sort() je O(nlog(n)).
Pomoćni prostor : O(1)
Sortiranje ArrayList silaznim redoslijedom
JAVA// Java program to demonstrate working of Collections.sort() // to descending order. import java.util.*; public class Collectionsorting { public static void main(String[] args) { // Create a list of strings ArrayList<String> al = new ArrayList<String>(); al.add('Geeks For Geeks'); al.add('Friends'); al.add('Dear'); al.add('Is'); al.add('Superb'); /* Collections.sort method is sorting the elements of ArrayList in ascending order. */ Collections.sort(al Collections.reverseOrder()); // Let us print the sorted list System.out.println('List after the use of' + ' Collection.sort() :n' + al); } }
Izlaz
List after the use of Collection.sort() : [Superb Is Geeks For Geeks Friends Dear]
Vremenska složenost: O(N log N) kao vremenska složenost Collections.sort() je O(nlog(n)).
Pomoćni prostor: O(1)
Sortiranje ArrayList-a prema korisnički definiranim kriterijima. Možemo koristiti Sučelje komparatora za ovu svrhu.
Java// Java program to demonstrate working of Comparator // interface and Collections.sort() to sort according // to user defined criteria. import java.util.*; import java.lang.*; import java.io.*; // A class to represent a student. class Student { int rollno; String name address; // Constructor public Student(int rollno String name String address) { this.rollno = rollno; this.name = name; this.address = address; } // Used to print student details in main() public String toString() { return this.rollno + ' ' + this.name + ' ' + this.address; } } class Sortbyroll implements Comparator<Student> { // Used for sorting in ascending order of // roll number public int compare(Student a Student b) { return a.rollno - b.rollno; } } // Driver class class Main { public static void main (String[] args) { ArrayList<Student> ar = new ArrayList<Student>(); ar.add(new Student(111 'bbbb' 'london')); ar.add(new Student(131 'aaaa' 'nyc')); ar.add(new Student(121 'cccc' 'jaipur')); System.out.println('Unsorted'); for (int i=0; i<ar.size(); i++) System.out.println(ar.get(i)); Collections.sort(ar new Sortbyroll()); System.out.println('nSorted by rollno'); for (int i=0; i<ar.size(); i++) System.out.println(ar.get(i)); } }
Izlaz
Unsorted 111 bbbb london 131 aaaa nyc 121 cccc jaipur Sorted by rollno 111 bbbb london 121 cccc jaipur 131 aaaa nyc
Arrays.sort() u odnosu na Collections.sort() Arrays.sort radi za nizove koji također mogu biti primitivnog tipa podataka. Zbirke .sort() radi za objekte zbirke poput ArrayList LinkedList itd. Možemo koristiti Collections.sort() za sortiranje niza nakon stvaranja ArrayList zadanih stavki niza.
// Using Collections.sort() to sort an array import java.util.*; public class Collectionsort { public static void main(String[] args) { // create an array of string objs String domains[] = {'Practice' 'Geeks' 'Code' 'Quiz'}; // Here we are making a list named as Collist List colList = new ArrayList(Arrays.asList(domains)); // Collection.sort() method is used here // to sort the list elements. Collections.sort(colList); // Let us print the sorted list System.out.println('List after the use of' + ' Collection.sort() :n' + colList); } }
Izlaz
List after the use of Collection.sort() : [Code Geeks Practice Quiz]
Vremenska složenost Arrays.sort() u odnosu na Collections.sort():
Arrays.sort() koristi algoritam Dual-Pivot Quicksort koji daje vremensku složenost od O(N.log N) što je obično brže od tradicionalnih algoritama Quicksort. S druge strane Collections.sort() stvara niz elemenata popisa razvrstava ih pomoću prilagodljivog Mergesort algoritma i ponavlja po popisu kako bi pozicionirao svaki element na njegovu ispravnu lokaciju. Stoga se za primitivne tipove podataka kao što je int char double itd. Arrays.sort() pokazao vremenski mnogo učinkovitijim od Collections.sort(). Problemi koji uključuju primitivne tipove podataka trebali bi se pokušati riješiti korištenjem Arrays.sort() za bolju optimizaciju.
Ispod je kod za demonstraciju razlike:
Java/*package whatever //do not write package name here */ import java.io.*; import java.util.*; class GFG { public static void main (String[] args) { int len = 5000000; // creating a large test array int[] arr = new int[len]; for (int i = len; i > 0; i--) arr[len - i] = i; // creating a large test arraylist ArrayList<Integer> list = new ArrayList<>(); for (int i = len; i > 0; i--) list.add(i); // calculating time used by arrays.sort() long startA = System.currentTimeMillis(); Arrays.sort(arr); long stopA = System.currentTimeMillis(); // calculating time used by collections.sort() long startAL = System.currentTimeMillis(); Collections.sort(list); long stopAL = System.currentTimeMillis(); System.out.println('Time taken by Arrays.sort(): ' + (stopA - startA)); System.out.println('Time taken by Collections.sort(): ' + (stopAL - startAL)); } } // This code is contributed by godcoder28
Izlaz
Time taken by Arrays.sort(): 29 Time taken by Collections.sort(): 42
Želja je da članak bude koristan cijenjenim Geekovima. .