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Convert arraylist to array in java with example program

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instanceof java

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Convert arraylist to array in java with example program Posted: Mar 19, 2017 9:01 AM
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  • 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. }



Output:
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

Program #2: Java example program to covert Integer arraylist to int array using toArray() method Using Java 8
  •  

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