收藏。Java中的sort（）及其示例-yiteyi-C++库

JAVAutil。收藏。排序（） 方法在java中存在。util。收藏课。它用于对指定区域中存在的元素进行排序列表按升序排列的集合。它的工作原理与 JAVAutil。数组。排序（）方法，但它比它更好，因为它可以对数组元素以及链表、队列和其中存在的更多元素进行排序。

null

public static void sort(List myList)

myList : A List type object we want to sort.

This method doesn't return anything

例子：


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"}

按升序排序ArrayList

                     // 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() :"                               + al);                   
                                         }                   
                     }                   

输出：

List after the use of Collection.sort() :
[Dear, Friends, Geeks For Geeks, Is, Superb]

按降序排列ArrayList

                     // 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() :"                               + al);                   
                                         }                   
                     }                   

输出：

List after the use of Collection.sort() :
[Superb, Is, Geeks For Geeks, Friends, Dear]

根据用户定义的条件对ArrayList进行排序。 我们可以使用比较器接口为此目的。

                     // 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(                               "Sorted by rollno"                               );                   
                                         for                               (                               int                               i=                               0                               ; i<ar.size(); i++)                   
                                         System.out.println(ar.get(i));                   
                                         }                   
                     }                   

输出：

Unsorted
111 bbbb london
131 aaaa nyc
121 cccc jaipur

Sorted by rollno
111 bbbb london
121 cccc jaipur
131 aaaa nyc

数组。排序（） vs系列。排序（） 数组。排序也适用于原始数据类型的数组。收藏 .sort（）适用于对象集合，如 ArrayList , 链表等

我们可以使用集合。sort（）在创建给定数组项的ArrayList后对数组进行排序。

                     // 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()  :"                               +                   
                                         colList);                   
                                         }                   
                     }                   

输出：

List after the use of Collection.sort()  :
[Code, Geeks, Practice, Quiz]

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