Java LinkedList toArray() Method

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Description

The Java LinkedList toArray() method returns an array containing all of the elements in this list in proper sequence (from first to last element).This acts as bridge between array-based and collection-based APIs. The returned array is safe to modify as no references to it is maintained by this list.

Declaration

Following is the declaration for java.util.LinkedList.toArray() method

public Object[] toArray()

Parameters

• NA

Return Value

This method returns an array containing all of the elements in this list in proper sequence.

Exception

NA

Java LinkedList toArray(T[] a) Method

Description

The Java LinkedList toArray(a) method returns an array containing all of the elements in this list from first to last element). It returns the runtime type of the returned array as of the specified array. In case of list fits in the specified array, it is returned. Otherwise, a new array is allocated with the specified runtime type and the size of current list.

Declaration

Following is the declaration for java.util.LinkedList.toArray(T[] a) method

public <T> T[] toArray(T[] a)

Parameters

• a − the array into which the elements of the list are to be stored

Return Value

This method returns an array containing the elements of the list.

Exception

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.

Getting Array from a LinkedList of Integer Example

The following example shows the usage of Java LinkedList toArray() method. We're creating a LinkedList of Integers. We're adding couple of Integers to the LinkedList object using add() method calls per element and using toArray() method, we're getting array from the list and printing that array.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linked list 
      LinkedList<Integer> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(0);
      linkedList.add(1);
      linkedList.add(2);
      linkedList.add(3);
      linkedList.add(4);
      linkedList.add(5);
      linkedList.add(6);

      // get the array
      Object[] array = linkedList.toArray();

      // print the array elements
      for (Object object : array) {
         System.out.println(object);
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

0
1
2
3
4
5
6

Getting Array from a LinkedList of String Example

The following example shows the usage of Java LinkedList toArray() method. We're creating a LinkedList of Strings. We're adding couple of Strings to the LinkedList object using add() method calls per element and using toArray() method, we're getting array from the list and printing that array.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linked list
      LinkedList<String> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add("A");
      linkedList.add("B");
      linkedList.add("C");
      linkedList.add("D");
      linkedList.add("E");
      linkedList.add("F");
	  
      // get the array
      Object[] array = linkedList.toArray();

      // print the array elements
      for (Object object : array) {
         System.out.println(object);
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

A
B
C
D
E
F

Getting Array from a LinkedList of Object Example

The following example shows the usage of Java LinkedList toArray(T[] a) method. We're creating a LinkedList of Integers. We're adding couple of Integers to the LinkedList object using add() method calls per element and using toArray(T[]) method, we're getting array of Student objects from the list and printing that array.

package com.tutorialspoint;

import java.util.LinkedList;

public class LinkedListDemo {
   public static void main(String[] args) {

      // create an empty linkedList
      LinkedList<Student> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(new Student(1, "Julie"));
      linkedList.add(new Student(2, "Robert"));
      linkedList.add(new Student(3, "Adam"));
	  
      // get the array of Student objects
      Student[] array = linkedList.toArray(new Student[linkedList.size()]);

      // print the array elements
      for (Student student : array) {
         System.out.println(student);
      }  
   }
}

class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
   
   @Override
   public boolean equals(Object obj) {
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name);
   }
}

Output

Let us compile and run the above program, this will produce the following result −

[ 1, Julie ]
[ 2, Robert ]
[ 3, Adam ]