Convert List to Array in Java
The List interface provides a way to store the ordered collection. It is a child interface of Collection. It is an ordered collection of objects in which duplicate values can be stored. Since List preserves the insertion order, it allows positional access and insertion of elements. Now here we are given a List be it any LinkedList or ArrayList of strings, our motive s to convert this list to an array of strings in java using different methods.
Methods:
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- Using get[] method
- Using toArray[] method
- Using Stream introduced in Java 8
Method 1: Using get[] method
We can use the below list method to get all elements one by one and insert them into an array.
Return Type: The element at the specified index in the list.
Syntax:
public E get[int index]Example:
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// Java program to Convert a List to an Array
// Using get[] method in a loop
// Importing required classes
import java.io.*;
import java.util.LinkedList;
import java.util.List;
// Main class
class GFG {
// Main driver method
public static void main[String[] args]
{
// Creating a LinkedList of string type by
// declaring object of List
List list = new LinkedList[];
// Adding custom element to LinkedList
// using add[] method
list.add["Geeks"];
list.add["for"];
list.add["Geeks"];
list.add["Practice"];
// Storing it inside array of strings
String[] arr = new String[list.size[]];
// Converting ArrayList to Array
// using get[] method
for [int i = 0; i < list.size[]; i++]
arr[i] = list.get[i];
// Printing elements of array on console
for [String x : arr]
System.out.print[x + " "];
}
}
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Method 2: Using toArray[] method
Example:
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// Java Program to Convert a List to an array
// using toArray[] Within a loop
// Importing utility classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main[String[] args]
{
// Creating an empty LinkedList of string type
// by declaring object of List
List list = new LinkedList[];
// Adding elements to above LinkedList
// using add[] method
list.add["Geeks"];
list.add["for"];
list.add["Geeks"];
list.add["Practice"];
// Converting List to array
// using toArray[] method
String[] arr = list.toArray[new String[0]];
// Printing elements of array
// using for-each loop
for [String x : arr]
System.out.print[x + " "];
}
}
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Method 3: Using Stream introduced in Java8
Example:
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// Java Program to Demonstrate conversion of List to Array
// Using stream
// Importing utility classes
import java.util.*;
// Main class
class GFG {
// Main driver method
public static void main[String[] args]
{
// Creating an empty LinkedList of string type
List list = new LinkedList[];
// Adding elements to above LinkedList
// using add[] method
list.add["Geeks"];
list.add["for"];
list.add["Geeks"];
list.add["Practice"];
// Storing size of List
int n = list.size[];
// Converting List to array via scope resolution
// operator using streams
String[] arr
= list.stream[].toArray[String[] ::new];
// Printing elements of array
// using enhanced for loop
for [String x : arr]
System.out.print[x + " "];
}
}
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Tip: We can convert the array back to the list via asList[] method.
Related Articles:
- ArrayList to Array Conversion in Java
- Set to Array in Java