In this tutorial, we will learn how to make immutable ArrayList with an example.
We will see two examples to make immutable ArrayList:
In this tutorial, we have seen how to make immutable ArrayList using Collections.unmodifiableList() method and Java 9 List.of() factory method with an example.
We will see two examples to make immutable ArrayList:
- First, we will see how to create an immutable ArrayList using Collections.unmodifiableList() method with an example
- Second, we will see how to create the Immutable ArrayList with Java 9 List.of() factory method example.
Create Immutable ArrayList with Collections.unmodifiableList() Exmaple
In the following, we create an immutable ArrayList using Collections.unmodifiableList() method with an example
public class ImmutableListExample {
public static void main(String[] args) {
// Creating an ArrayList of String using
List < String > fruits = new ArrayList < > ();
// Adding new elements to the ArrayList
fruits.add("Banana");
fruits.add("Apple");
fruits.add("mango");
fruits.add("orange");
fruits = Collections.unmodifiableList(fruits);
// Creating Immutable List
//fruits.add("Strawberry"); // Exception in thread "main"
// java.lang.UnsupportedOperationException<String> fruits = List.of("Banana", "Apple", "Mango", "Orange");
fruits.forEach(e - > System.out.println(e));
}
}
Output:
Banana
Apple
mango
orange
Create the Immutable ArrayList Example - Java 9 List.of() Method
Let's use List.of() static factory methods to create immutable ArrayList.
package net.javaguides.corejava.java9;
import java.util.List;
/**
* Java 9 Immutable List Example
* @author Ramesh Fadatare
*
*/
public class ImmutableListExample {
public static void main(String[] args) {
// Creating Immutable List
List < String > fruits = List.of("Banana", "Apple", "Mango", "Orange");
fruits.forEach(e - > System.out.println(e));
// You can't add Elements Immutable List
// fruits.add("Strawberry"); // Exception in thread "main" java.lang.UnsupportedOperationException
// in single list
List < String > list = List.of("A", "B", "C", "D");
list.forEach(e - > System.out.println(e));
}
}
Output:
Banana
Apple
mango
orange
A
B
C
D
Comments
Post a comment