CopyOnWriteArrayList toArray() method in Java
Last Updated :
18 Dec, 2018
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:
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
CopyOnWriteArrayList<Integer> ArrLis
= new CopyOnWriteArrayList<Integer>();
ArrLis.add( 32 );
ArrLis.add( 67 );
ArrLis.add( 98 );
ArrLis.add( 100 );
System.out.println( "CopyOnWriteArrayList: "
+ ArrLis);
Object[] arr = ArrLis.toArray();
System.out.println( "Elements of CopyOnWriteArrayList"
+ " as Array: "
+ Arrays.toString(arr));
}
}
|
Output:
CopyOnWriteArrayList: [32, 67, 98, 100]
Elements of CopyOnWriteArrayList as Array: [32, 67, 98, 100]
Program 2:
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
CopyOnWriteArrayList<Integer> ArrLis
= new CopyOnWriteArrayList<Integer>();
ArrLis.add( 32 );
ArrLis.add( 67 );
ArrLis.add( 98 );
ArrLis.add( 100 );
System.out.println( "CopyOnWriteArrayList: "
+ ArrLis);
Integer arr[] = new Integer[ArrLis.size()];
arr = ArrLis.toArray(arr);
System.out.println( "Elements of CopyOnWriteArrayList"
+ " as Array: "
+ Arrays.toString(arr));
}
}
|
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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