- Java.util Package Classes
- Java.util - Home
- Java.util - ArrayDeque
- Java.util - ArrayList
- Java.util - Arrays
- Java.util - BitSet
- Java.util - Calendar
- Java.util - Collections
- Java.util - Currency
- Java.util - Date
- Java.util - Dictionary
- Java.util - EnumMap
- Java.util - EnumSet
- Java.util - Formatter
- Java.util - GregorianCalendar
- Java.util - HashMap
- Java.util - HashSet
- Java.util - Hashtable
- Java.util - IdentityHashMap
- Java.util - LinkedHashMap
- Java.util - LinkedHashSet
- Java.util - LinkedList
- Java.util - ListResourceBundle
- Java.util - Locale
- Java.util - Observable
- Java.util - PriorityQueue
- Java.util - Properties
- Java.util - PropertyPermission
- Java.util - PropertyResourceBundle
- Java.util - Random
- Java.util - ResourceBundle
- Java.util - ResourceBundle.Control
- Java.util - Scanner
- Java.util - ServiceLoader
- Java.util - SimpleTimeZone
- Java.util - Stack
- Java.util - StringTokenizer
- Java.util - Timer
- Java.util - TimerTask
- Java.util - TimeZone
- Java.util - TreeMap
- Java.util - TreeSet
- Java.util - UUID
- Java.util - Vector
- Java.util - WeakHashMap
- Java.util Package Extras
- Java.util - Interfaces
- Java.util - Exceptions
- Java.util - Enumerations
- Java.util Useful Resources
- Java.util - Useful Resources
- Java.util - Discussion
Java Collections unmodifiableList() Method
Description
The Java Collections unmodifiableList() method is used to returns an unmodifiable view of the specified list.
Declaration
Following is the declaration for java.util.Collections.unmodifiableList() method.
public static <T> List<T> unmodifiableList(List<? extends T> list)
Parameters
list − This is the list for which an unmodifiable view is to be returned.
Return Value
The method call returns an unmodifiable view of the specified list.
Exception
NA
Getting Immutable List From a Mutable List of Integer Example
The following example shows the usage of Java Collection unmodifiableList(List) method. We've created a List object with some integers. Using unmodifiableList(List) method, we've retrieved the immutable version of list and printed the list.
package com.tutorialspoint; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String[] args) { List<Integer> list = new ArrayList<>(Arrays.asList(1,2,3,4,5)); // immutable version of list List<Integer> c = Collections.unmodifiableList(list); System.out.println("Immutable list: "+ c); } }
Output
Let us compile and run the above program, this will produce the following result −
Immutable list: [1, 2, 3, 4, 5]
Getting Immutable List From a Mutable List of String Example
The following example shows the usage of Java Collection unmodifiableList(List) method. We've created a List object with some strings. Using unmodifiableList(List) method, we've retrieved the immutable version of list and printed the list.
package com.tutorialspoint; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String[] args) { List<String> list = new ArrayList<>(Arrays.asList("Welcome","to","Tutorialspoint")); // immutable version of list List<String> c = Collections.unmodifiableList(list); System.out.println("Immutable list: "+ c); } }
Output
Let us compile and run the above program, this will produce the following result −
Immutable list: [Welcome, to, Tutorialspoint]
Getting Immutable List From a Mutable List of Object Example
The following example shows the usage of Java Collection unmodifiableList(List) method. We've created a List object with some Student objects. Using unmodifiableList(List) method, we've retrieved the immutable version of list and printed the list.
package com.tutorialspoint; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; public class CollectionsDemo { public static void main(String[] args) { List<Student> list = new ArrayList<>(Arrays.asList(new Student(1, "Julie"), new Student(2, "Robert"), new Student(3, "Adam"))); // immutable version of list List<Student> c = Collections.unmodifiableList(list); System.out.println("Immutable list: "+ c); } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } }
Output
Let us compile and run the above program, this will produce the following result −
Immutable list: [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]]
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