CopyOnWriteArrayList toArray() method in Java

The toArray() method of CopyOnWriteArrayList is used to return an array containing all the elements in CopyOnWriteArrayList in the correct order.

Syntax:

public Object[] toArray()
           or
public <T> T[] toArray(T[] a)

Parameters: This method either accepts no parameters or it takes an array T[] a as parameter which is the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.

Return Value: The function returns an array containing all the elements in this list.

Exception: The first overload of this method throws no exceptions. However, the second overload throws following exceptions:



  • ArrayStoreException: if the runtime type of the specified array is not a supertype of the runtime type of every element in this list.
  • NullPointerException if the specified array is null

Below programs illustrate the CopyOnWriteArrayList.toArray() method:

Program 1:

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// Java Program to illustrate the
// CopyOnWriteArrayList toArray() method in Java
  
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create object of CopyOnWriteArrayList
        CopyOnWriteArrayList<Integer> ArrLis
            = new CopyOnWriteArrayList<Integer>();
  
        // Add elements
        ArrLis.add(32);
        ArrLis.add(67);
        ArrLis.add(98);
        ArrLis.add(100);
  
        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList: "
                           + ArrLis);
  
        // Get the array of the elements
        // of the CopyOnWriteArrayList
        // using toArray() method
        Object[] arr = ArrLis.toArray();
  
        System.out.println("Elements of CopyOnWriteArrayList"
                           + " as Array: "
                           + Arrays.toString(arr));
    }
}

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Output:


CopyOnWriteArrayList: [32, 67, 98, 100]
Elements of CopyOnWriteArrayList as Array: [32, 67, 98, 100]





Program 2: 











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// Java Program to illustrate the 


// CopyOnWriteArrayList toArray(T[]) method in Java 


  


import java.util.concurrent.CopyOnWriteArrayList; 


import java.util.*; 


  


public class GFG { 


    public static void main(String[] args) 


    { 


  


        // create object of CopyOnWriteArrayList 


        CopyOnWriteArrayList<Integer> ArrLis 


            = new CopyOnWriteArrayList<Integer>(); 


  


        // Add elements 


        ArrLis.add(32); 


        ArrLis.add(67); 


        ArrLis.add(98); 


        ArrLis.add(100); 


  


        // print CopyOnWriteArrayList 


        System.out.println("CopyOnWriteArrayList: "


                           + ArrLis); 


  


        // Get the array of the elements 


        // of the CopyOnWriteArrayList 


        // using toArray(T[]) method 


        Integer arr[] = new Integer[ArrLis.size()]; 


        arr = ArrLis.toArray(arr); 


  


        System.out.println("Elements of CopyOnWriteArrayList"


                           + " as Array: "


                           + Arrays.toString(arr)); 


    } 


} 



















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Output:


CopyOnWriteArrayList: [32, 67, 98, 100]
Elements of CopyOnWriteArrayList as Array: [32, 67, 98, 100]





Reference: CopyOnWriteArrayList.toArray() doc, CopyOnWriteArrayList.toArray(T[]) doc



          
          
          
          

            

    

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