Java Collections sort() Method

The sort() method of Java Collections class is used to sort the elements presents in the specified list. There is two different types of Java sort() method which can be differentiated depending on its parameter. These are:

Java Collections sort(list) Method
Java Collections sort(list, comp) Method

Java Collections sort(list) Method

This method is used to sort the elements presents in the specified list of collection in ascending order.

Java Collections sort(list, comp) Method

This method is used to sorts the specified list according to the order introduced by the specified comparator.

Syntax

Following is the declaration of sort() ~~method:~~

  public static <T extends Comparable<? super T>> void sort(List<T> list)  public static <T> void sort(List<T> list, Comparator<? super T> comp)  

Parameter

Parameter	Description	Required/Optional
list	It is the list which will be sorted.	Required
comp	It is the comparator which determines the order of the list.	Required

Returns

The sort() method does not return anything.

Exceptions

UnsupportedOperationException– This method thrown exception if the specified list or its list-iterator does not support the set operation.

ClassCastException– This method thrown exception if the list contains elements that are not mutually comparable (for example, strings and integers).

Example 1

  import java.util.*;  public class CollectionsSortExample1 {  public static void main(String[] args) {      //Create an array of string objects      String str[] = { “Java”,”Python”,”Android”,”One”,”Ruby”,”Node.js”};      //Create list      List list = new ArrayList<>(Arrays.asList(str));      System.out.println(“Specified value before sort: “+list);      //Sort the list      Collections.sort(list);      System.out.println(“Specified value after sort: “+list);      }  }  

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Output:

Specified value before sort: [Java, Python, Android, One, Ruby, Node.js]  Specified value after sort: [Android, Java, Node.js, One, Python, Ruby]

Example 2

  import java.util.*;  public class CollectionsSortExample2 {  public static void main(String[] args) {      //Create an array of string objects      String str[] = { “Java”,”Python”,”Android”,”One”,”Ruby”,”Node.js”};      //Create list      List list = new ArrayList<>(Arrays.asList(str));      System.out.println(“Value before sort: “+list);      //Sort the list according to specified comparator      Collections.sort(list,Collections.reverseOrder());      System.out.println(“Sort Value according to specified comparator: “+list);      }  }  

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Output:

Value before sort: [Java, Python, Android, One, Ruby, Node.js]  Sort Value according to specified comparator: [Ruby, Python, One, Node.js, Java, Android]

Example 3

  import java.util.*;  public class CollectionsSortExample3 {  public static void main(String[] args) {  ArrayList al=new ArrayList<>();    al.add(Integer.valueOf(201));    al.add(Integer.valueOf(101));    al.add(230);//internally will be converted into objects as Integer.valueOf(230)    Collections.sort(al);      Iterator itr=al.iterator();    while(itr.hasNext()){    System.out.println(itr.next());     }               }  }  

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Output:

101  201  230

Example 4

  import java.util.*;  public class CollectionsSortExample4 {  public static void main (String[] args)      {          ArrayList arr = new ArrayList();          arr.add(new Student(101, “Java”, “USA”));          arr.add(new Student(103, “Ruby”, “China”));          arr.add(new Student(102, “Android”, “India”));          System.out.println(“Data before sorted-“);          for (int i=0; i  {  //Used for sorting in ascending order of roll number  public int compare(Student a, Student b)  {  return a.rollno – b.rollno;  }  }  ();>

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Output:

Data before sorted-  101 Java USA  103 Ruby China  102 Android India  Data after sorted by rollno-  101 Java USA  102 Android India  103 Ruby China

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Java Collections sort() Method with Examples

Java Collections sort() Method

Java Collections sort(list) Method

Java Collections sort(list, comp) Method

Syntax

Parameter

Returns

Exceptions

Example 1

Example 2

Example 3

Example 4

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