Collections checkedList() method in Java with Examples

Last Updated : 20 May, 2019

The checkedList() method of java.util.Collections class is used to return a dynamically typesafe view of the specified list.

The returned list will be serializable if the specified list is serializable.

Since null is considered to be a value of any reference type, the returned list permits insertion of null elements whenever the backing list does.

Syntax:

public static  List
    checkedList(List list, Class type)

Parameters: This method takes the following arguments as a 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

Return Value: This method returns a dynamically typesafe view of the specified list

Below are the examples to illustrate the checkedList() method

Example 1:

// Java program to demonstrate
// checkedList() method
// for String value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
        try {
  
            // creating object of List<String>
            List<String> arlst = new ArrayList<String>();
  
            // Adding element to arlst
            arlst.add("A");
            arlst.add("B");
            arlst.add("C");
            arlst.add("TajMahal");
  
            // printing the arrlist
            System.out.println("List: " + arlst);
  
            // create typesafe view of the specified list
            List<String>
                tslst = Collections
                            .checkedList(arlst, String.class);
  
            // printing the arrlist after operation
            System.out.println("Typesafe view of List: " + tslst);
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

List: [A, B, C, TajMahal]
Typesafe view of List: [A, B, C, TajMahal]

Example 2:

// Java program to demonstrate
// checkedList() method
// for Integer value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv) throws Exception
    {
  
        try {
  
            // creating object of List<Integer>
            List<Integer> arlst = new ArrayList<Integer>();
  
            // Adding element to arlst
            arlst.add(20);
            arlst.add(30);
            arlst.add(40);
            arlst.add(50);
  
            // printing the arrlist
            System.out.println("List: " + arlst);
  
            // create typesafe view of the specified list
            List<Integer>
                tslst = Collections
                            .checkedList(arlst, Integer.class);
  
            // printing the arrlist after operation
            System.out.println("Typesafe view of List: " + tslst);
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

List: [20, 30, 40, 50]
Typesafe view of List: [20, 30, 40, 50]

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