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How do you convert an ArrayList to an array in Java?
An ArrayList provides two methods to convert it into Array.
Way #1
Object[] toArray()
Returns an array containing all of the elements in this list in proper sequence (from first to last element).
Way #2
<T> T[] toArray(T[] a)
Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.
Type Parameter
T − The runtime type of the array to contain the collection.
Parameters
a − The array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
Returns
An array containing the elements of this list.
Throws
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.
Example
Following is the example showing the usage of toArray() methods −
package com.tutorialspoint;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class CollectionsDemo {
public static void main(String[] args) {
List<String> list = new ArrayList<>(Arrays.asList("A","B","C", "D"));
System.out.println("List: " + list);
Object[] items = list.toArray();
for (Object object : items) {
System.out.print(object + " ");
}
System.out.println();
String[] characters = list.toArray(new String[list.size()]);
for (String string : characters) {
System.out.print(string + " ");
}
}
}Output
This will produce the following result −
List: [A, B, C, D] A B C D A B C D
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