Java List.sort() Method

The sort() method is used to sort the elements of a List in ascending order according to their natural ordering or using a custom Comparator provided by the user. The List interface belong to the java.util package. It extends the Collection interface. The list must be modifiable else it will throw an exception.

Syntax

Parameters

The parameter 'c' represents the Comparator used to compare list elements. And for null values, natural ordering is used.

Return

NA

Exceptions:

ClassCastException: It is thrown if the list contains elements that are not mutually comparable and the natural ordering of these elements is not defined.

UnsupportedOperationException: It is raised if the list-iterator of the specified list doesn't support set operation during sorting. It can happen, for example, if an immutable data structure backs the list or if the iterator of the list does not support modification operations.

IllegalArgumentException: It is thrown if the contract of the Comparator has been violated. For example, the comparator could return inconsistent results when comparing certain elements, or an exception could be thrown when comparing elements.

NullPointerException: The exception can be thrown in a number of situations:

• If the specified list is null.
• If the specified comparator is null and the list's elements are not comparable to each other.
• If any element in the list is null and the comparator does not support null values.

ConcurrentModificationException: This exception can be raised if the list is structurally modified while sorting is going on. For instance, when new elements are added, removed, or modified in the list while the sort() method is running without proper synchronization.

Example 1

JavaListSortExample.java

Output:

Original List: [Renu, Heera, Vijay, Geetanjali]
Sorted List (Ascending Order): [Geetanjali, Heera, Renu, Vijay]
Sorted List (Descending Order): [Vijay, Renu, Heera, Geetanjali] 

Example 2

EmployeeSortingExample.java

Output:

Unsorted List :
1. 15019 Patanjali
2. 13198 Geetanjali
3. 12112 Anjali

 Sorted List :
1. 12112 Anjali
2. 13198 Geetanjali
3. 15019 Patanjali