Arraylist.iterator - Java ArrayList iterator() Method with Example

Arraylist.iterator: In the previous article we have discussed about Java ArrayList trimToSize() Method with Example

In this article we are going to see the use Java ArrayList iterator() method along with suitable examples.

Java ArrayList iterator() Method with Example

iterator():

Arraylist iterator java: This java.util.ArrayList.iterator() method is used to get an iterator to retrieve each element of the ArrayList in a proper order.

Syntax:

arrayListName.iterator()

Where,

arrayListName refers to the name of your ArrayList.

Let’s see different examples to understand it more clearly.

Example with String Type ArrayList
Example with Integer Type ArrayList

Method-1: Java ArrayList iterator() Method – Example with String Type ArrayList

Approach:

Create a new ArrayList of type String.
Add string elements into the ArrayList using the add() method.
Display the ArrayList elements.
Create a variable of Iterator and store the value returned by iterator() method.
Use a while loop through ArrayList till it has all elements.
Inside iterator() method there is some inbuild methods like next() to access elements.
Print the arrayList.

Program:

import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
        // Create an ArrayList of string datatype
        ArrayList<String> arr1 = new ArrayList<String>();
        // Adding some elements to the ArrayList
        arr1.add("vivo");
        arr1.add("htc");
        arr1.add("samsung");
        arr1.add("realme");
        arr1.add("nokia");
        // Prints the ArrayList elements
        System.out.println("The elements in the ArrayList are: "+arr1);
        // Create a variable of Iterator and store the value returned by iterator() method
        Iterator<String> iterate = arr1.iterator();
        System.out.print("ArrayList: ");
        // loop through ArrayList till it has all elements
        while(iterate.hasNext())
        {
            // Use methods of Iterator to access elements
            System.out.print(iterate.next());
            System.out.print("  ");
        }
    }
}

Output:

The elements in the ArrayList are: [vivo, htc, samsung, realme, nokia]
ArrayList: vivo htc samsung realme nokia

Method-2: Java ArrayList iterator() Method – Example with Integer Type ArrayList

Approach:

Create a new ArrayList of type Integer.
Add Integer elements into the ArrayList using the add() method.
Display the ArrayList elements.
Create a variable of Iterator and store the value returned by iterator()
Use a while loop through ArrayList till it has all elements.
Inside iterator() method there is some inbuild methods like next() to access elements.
Now using if condition we will filter the elements and remove those elements which are less than 20 from the arrayList.
Print the arrayList.

Program:

import java.util.*;
public class Main
{
    public static void main(String[] args)
    {  
        // Create an ArrayList of Integer datatype
        ArrayList<Integer> arr1 = new ArrayList<Integer>();
        // Adding some elements to the ArrayList
        arr1.add(1);
        arr1.add(100);
        arr1.add(84);
        arr1.add(17);
        arr1.add(0);
        // Prints the ArrayList elements
        System.out.println("The elements in the ArrayList are: "+arr1);
        // Create a variable of Iterator and store the iterator returned by iterator()
        Iterator<Integer> iterate = arr1.iterator();
        System.out.print("ArrayList: ");
        // loop through ArrayList till it has all elements
        while(iterate.hasNext())
        {
            // Use methods of Iterator to access elements
            Integer i = iterate.next();
            if(i < 20)
            iterate.remove();
        }
        System.out.println(arr1);
    }
}

Output:

The elements in the ArrayList are: [1, 100, 84, 17, 0]
ArrayList: [100, 84]

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