Click here to watch in Youtube :https://www.youtube.com/watch?v=xe3VJT4rc7M&list=UUhwKlOVR041tngjerWxVccwCollectionsExample.java import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/*
Method:
public static <E> List<E> checkedList(List<E> list, Class<E> type)
Parameters:
list - the list for which a dynamically typesafe view is to be returned
type - the type of element that list is permitted to hold
Returns:
a dynamically typesafe view of the specified list.
*/
public class CollectionsExample
{
public static void main(String[] args)
{
List myList = new ArrayList();
myList.add("one");
myList.add("two");
myList.add("three");
myList.add("four");
System.out.println("myList : " + myList + "\n");
/*
* Returns a dynamically typesafe view of the specified list.
*/
List chkList = Collections.checkedList(myList, String.class);
System.out.println("Checked list : " + chkList + "\n");
/*
* you can add any type of elements to myList object.
*/
myList.add(10);
System.out.println("myList : " + myList + "\n");
/*
* you cannot add any type of elements to chkList object, doing so
* throws ClassCastException.
*/
chkList.add(10);
System.out.println("Checked list : " + chkList + "\n");
}
}
Output myList : [one, two, three, four]
Checked list : [one, two, three, four]
myList : [one, two, three, four, 10]
Exception in thread "main" java.lang.ClassCastException: Attempt to insert class java.lang.Integer element into collection with element type class java.lang.String
at java.util.Collections$CheckedCollection.typeCheck(Collections.java:3037)
at java.util.Collections$CheckedCollection.add(Collections.java:3080)
at CollectionsExample.main(CollectionsExample.java:53)
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Java : Collection Framework : Collections (CheckedList) |
To Download CollectionsDemoCheckedList Project Click the below link