Iterating over ArrayLists in Java

Published on Oct 28, 2019 by Mukesh Kumar

In this post we will learn how to iterate (loop) ArrayList in Java.

There are 5 ways which is widely used to iterate through List which is mentioned below.

1. For loop
2. Enhanced For loop
3. Iterator
4. While loop
5. Java 8 Stream

1 . Iterate through ArrayList using for loop

Java program to iterate through an arraylist of objects using standard for loop.

package com.jwt.list.demo;

import java.util.ArrayList;

public class LoopDemo {

	public static void main(String as[]) {
		ArrayList<Integer> list = new ArrayList<>();
		list.add(1);
		list.add(10);
		list.add(25);
		list.add(32);
		System.out.println("Iterating using for Loop");
		for (int i = 0; i < list.size(); i++) {
			System.out.println(list.get(i));
		}
	}

}

Program Output:

Iterating using for Loop
1
10
25
32

2. Iterate through ArrayList with enhanced for loop

Java program to iterate through an arraylist of objects using foreach loop.

package com.jwt.list.demo;
package com.jwt.list.demo;

import java.util.ArrayList;

public class LoopDemo {

	public static void main(String as[]) {
		ArrayList<Integer> list = new ArrayList<>();
		list.add(1);
		list.add(10);
		list.add(25);
		list.add(32);
		System.out.println("Iterating using enhanced for loop ");
		for (Integer num : list) {
			System.out.println(num);
		}
	}

}

Program Output:

Iterating using enhanced for loop 
1
10
25
32

3. Iterate through ArrayList with iterator

Java program to iterate through an arraylist of objects using foreach loop.

package com.jwt.list.demo;
package com.jwt.list.demo;

import java.util.ArrayList;

public class LoopDemo {

	public static void main(String as[]) {
		ArrayList<Integer> list = new ArrayList<>();
		list.add(1);
		list.add(10);
		list.add(25);
		list.add(32);
		System.out.println("Iterating using Iterator ");
		Iterator<Integer> iterator = list.iterator();
		while (iterator.hasNext()) {
			System.out.println(iterator.next());
		}
	}

}

Program Output:

Iterating using Iterator 
1
10
25
32

4. Iterate through ArrayList with while loop

Java program to iterate through an arraylist of objects using while loop.

package com.jwt.list.demo;
package com.jwt.list.demo;

import java.util.ArrayList;

public class LoopDemo {

	public static void main(String as[]) {
		ArrayList<Integer> list = new ArrayList<>();
		list.add(1);
		list.add(10);
		list.add(25);
		list.add(32);
		System.out.println("Iterating using while loop ");
		int count = 0;
		while (list.size() > count) {
			System.out.println(list.get(count));
			count++;
		}
	}

}

Program Output:

Iterating using while loop 
1
10
25
32

5. Iterate through ArrayList with Java 8 stream

Java program to iterate through an arraylist of objects with Java 8 stream API.

package com.jwt.list.demo;
package com.jwt.list.demo;

import java.util.ArrayList;

public class LoopDemo {

	public static void main(String as[]) {
		ArrayList<Integer> list = new ArrayList<>();
		list.add(1);
		list.add(10);
		list.add(25);
		list.add(32);
		System.out.println("Iterating using Java 8 stream API");
		list.forEach(number -> System.out.println(number));
	}

}

Program Output:

Iterating using Java 8 stream API
1
10
25
32