Home Java Example Java Util Collection to Array

Collection to Array
Posted on: July 6, 2007 at 12:00 AM

In this section, you will learn to convert the collection into a array with the help of example.

Collection to Array

The example given below illustrates the conversion of a collection into a array. In this example we creating an object of ArrayList, adding elements into this object and storing this object into List interface. Convert elements of ArrayList into an array by using toArray().

List interface is a member of the Java Collection Framework and extends Collection interface. It is an ordered collection which follows insertion order, typically allow duplicate elements. The class ArrayList extends AbstractList class and implements List, RandomAccess, Cloneable, Serializable interfaces. ArrayList class is a member of the Java Collections Framework.

The method used:
toArray(Object[] a): This method returns an array containing all of the elements of the given list.

The code of the program is given below:


import java.util.List;

import java.util.ArrayList;

 

public class CollectionToArray1{

  public static void main(String[] args){

  List arraylist = new ArrayList();

  arraylist.add("Java");

  arraylist.add("Struts");

  arraylist.add("J2ee");

  arraylist.add("Code");

  Object[] array = arraylist.toArray();

  System.out.println("\nThe objects into array.");

  for (int i = 0; i < array.length; i++)

  {

 System.out.println(array[i].toString());

  }

  }

}

The output of the program is given below:

C:\rajesh\kodejava>javac CollectionToArray.java
Note: CollectionToArray.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

C:\rajesh\kodejava>java CollectionToArray

The objects into array.
Java
Struts
J2ee
Code

Download this example.

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