Convert arraylist to array in java with example program

• Inoder to convert arraylist to array normally we will try to iterate arraylist using loop and get each element and put it in an array.
• But you know we have a predefined method in arraylist which convert list to array of elements in sequence order.
• toArray() method inside arraylist class.

1. public <T> T[] toArray(T[] a) {  }

•  Lets see a java program on how to convert arraylist to array.

 Program #1: Java example program to covert arraylist to array using toArray() method

1. package arraysinterview;
2. import java.util.ArrayList;
3. import java.util.List;
4.  
5. public class ArrayListTOArray {
6.  
7.     public static void main(String[] args) {
8.         List<String> list = new ArrayList<String>();
9.         
10.         list.add("array");
11.         list.add("arraylist");
12.         list.add("convertion");
13.         list.add("javaprogram");
14.         
15.         String [] str = list.toArray(new String[list.size()]);
16.         
17.         for (int i = 0; i < str.length; i++) {
18.             System.out.println(str[i]);
19.         }
20.  
21.     }
22.  
23. }

Output:

1. array
2. arraylist
3. convertion
4. javaprogram

Program #2: Java example program to covert Integer arraylist to int array using toArray() method

•  In this case toArray() method gives Integer array so we need to convert again Integer array to int array.

1. package arraysinterview;
2. import java.util.ArrayList;
3. import java.util.List;
4.  
5. public class ArrayListTOArray {
6.  
7.  public static void main(String[] args) {
8.         List<Integer> list = new ArrayList<Integer>();
9.         
10.         list.add(10);
11.         list.add(20);
12.         list.add(30);
13.         list.add(40);
14.         list.add(50);
15.         
16.         Object[] integers = list.toArray();
17.         
18.         int[] intarray = new int[integers.length];
19.         int i = 0;
20.         for (Object n : integers) {
21.             intarray[i++] = (Integer) n;
22.             System.out.println(i);
23.         }
24.  
25.     }
26.  
27. }
28. 
    

Output:

1. 1
2. 2
3. 3
4. 4
5. 5