Collections

how to convert LinkedList to simple Array using Collections in java
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In this example we will see how can we convert a LinkedList to a linear Array.

In this example we have created a class CollectionExample. For using LinkedList we have
to import the java.util package.
 In this example we have used the toArray() method defined in the java.util package. The syntax of the toArray() method used in the following example is,

toArray(Anytypearray[] array)
This method returns an array containing all of the elements of the list in its order; the runtime type of the returned array is that of the specified array.

In the following example we have created a LinkedList named list. We also created an Integer array that is exactly of same size as that of the list, which is done by the following statement,
Integer[] arr=new Integer[list.size()];  

Then we have used the toArray(Anytypearray[] array) method on the list and stored all the elements of the list to the Integer array named arr. Finally we have diaplayed the elements of the array(which is created i.e arr) using the for loop.

 
package r4r.co.in;
import java.util.*;
import java.util.ListIterator;



public class CollectionExample {

/**
* @param args
*/
public static void main(String[] args)
{
// TODO Auto-generated method stub


LinkedList<Integer> list=new LinkedList<Integer>(); // creating a LinkedList of Object type elements
list.add(1); // adding integer values to the LinkedList
list.add(2);
list.add(50); // adding String values to the LinkedList
list.add(70);
list.add(7);
System.out.println("The contents of the list are :");
ListIterator<Integer> ltr=list.listIterator();
while(ltr.hasNext())
{
System.out.println(ltr.next()); // displaying the contents of the list
}

list.set(2, 700); // replacing the value contained at index 2 by 700
System.out.println("After replacing the value at the index 2 we have the list as:");
System.out.println(list); // now displaying the list elements after replacing the element
Integer[] arr=new Integer[list.size()]; // creating an Integer array of same size as that of the list
arr=list.toArray(arr); //converting the linkedlist list to array
System.out.println("The elements of the array are as follows:");
for(int i=0;i<arr.length;i++)
System.out.println(arr[i]); // displaying the contents of the array


}


}
The output of the above written program is as follows:

The contents of the list are :
1
2
50
70
7
After replacing the value at the index 2 we have the list as:
[1, 2, 700, 70, 7]
The elements of the array are as follows:
1
2
700
70
7

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