JavaHow-ToBeginner · 3 min read

How to Iterate Over List in Java: Simple Syntax and Examples

To iterate over a list in Java, you can use a for-each loop which goes through each element one by one. Alternatively, you can use an Iterator or Java 8's stream() method to process list elements.

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Syntax

Here are common ways to iterate over a list in Java:

For-each loop: Simplest way to access each element.
Iterator: Gives more control, can remove elements safely.
Stream API: Modern way to process elements with functional style.

java

import java.util.List;
import java.util.Iterator;

List<String> list = List.of("apple", "banana", "cherry");

// For-each loop
for (String item : list) {
    System.out.println(item);
}

// Iterator
Iterator<String> iterator = list.iterator();
while (iterator.hasNext()) {
    System.out.println(iterator.next());
}

// Stream API
list.stream().forEach(System.out::println);

Output

apple banana cherry apple banana cherry apple banana cherry

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Example

This example shows how to print all elements of a list using a for-each loop.

java

import java.util.List;

public class IterateListExample {
    public static void main(String[] args) {
        List<String> fruits = List.of("apple", "banana", "cherry");
        for (String fruit : fruits) {
            System.out.println(fruit);
        }
    }
}

Output

apple banana cherry

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Common Pitfalls

Common mistakes when iterating over lists include:

Modifying the list inside a for-each loop, which causes ConcurrentModificationException.
Using a regular for loop with incorrect index bounds.
Not checking if the list is empty before iterating, which is usually safe but sometimes leads to logic errors.

Use an Iterator if you need to remove elements during iteration.

java

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class PitfallExample {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>(List.of("a", "b", "c"));

        // Wrong: modifying list inside for-each loop causes error
        // for (String s : list) {
        //     if (s.equals("b")) {
        //         list.remove(s); // Throws ConcurrentModificationException
        //     }
        // }

        // Right: use Iterator to remove safely
        Iterator<String> it = list.iterator();
        while (it.hasNext()) {
            if (it.next().equals("b")) {
                it.remove();
            }
        }

        System.out.println(list); // Output: [a, c]
    }
}

Output

[a, c]

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Quick Reference

Summary of ways to iterate over a list in Java:

Method	Description	When to Use
For-each loop	Simple and readable way to access each element	Most common cases
Iterator	Allows safe removal of elements during iteration	When modifying list while iterating
Stream API	Functional style processing with lambda expressions	For complex data processing or chaining operations
Classic for loop	Using index to access elements	When index is needed or list is mutable

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Key Takeaways

Use for-each loop for simple and clear iteration over lists.

Use Iterator to safely remove elements during iteration.

Stream API offers a modern, functional way to process list elements.

Avoid modifying a list inside a for-each loop directly to prevent errors.

Classic for loops are useful when you need the index of elements.