# Iterating through Map, List, Set, and Array in Thymeleaf

By Atta Ur Rehman Shah (https://attacomsian.com/about). Published Jan 25, 2020, updated Jan 29, 2020. Topics: Thymeleaf.
Canonical URL: https://attacomsian.com/blog/thymeleaf-iterate-map-list-set-array

> A quick guide to learn how to map through an iterator like Map, List, Set, and Array in Thymeleaf.

[Thymeleaf](https://www.thymeleaf.org/) is a popular **server-side template engine** for Java-based web and standalone applications. It is used for processing XML, HTML, JavaScript, CSS, and other documents.

In this quick article, you'll **learn how to iterate through common Java collections** like a `Map`, `List`, `Set` and array in a Thymeleaf and Spring Boot application. For more information about Thymeleaf integration with Spring Boot, take a look at the [introductory tutorial](https://attacomsian.com/blog/spring-boot-thymeleaf-example).

## Java Model Class

Before we jump to actual work — iterating collections in Thymeleaf, let us first create a simple Java model class called `User.java` that stores the user information as shown below:

<p class="file-desc"><span>User.java</span></p>

```java
public class User implements Serializable {

    private String firstName;
    private String lastName;
    private String email;
    private int age;
    private Date created;

    // constructor, getters, and setters removed for brevity
}
```

## Thymeleaf `th:each` Attribute

The `th:each` attribute is a special attribute provided by Thymeleaf template engine to **loop through different data collections**. Here is the example:

```markup
<div th:each="iter : ${iterableObject}">
    <!-- do whatever you wan to do here -->
</div>
```

### Iterable values

The `th:each` attribute is not just limited to `List` or `Map`.  Several objects qualify as an iterable that can be iterated over using the Thymeleaf's `th:each` attribute:

* An object implementing `java.util.Iterable`
* An object implementing `java.util.Enumeration`
* An object implementing `java.util.Iterator`, whose values will be used as they are returned by the iterator, without the need to cache all values in memory.
* An object implementing `java.util.Map`. When iterating maps, `iter` variables will be of type `java.util.Map.Entry`.
* An array
* Any other object will be treated as if it were a single-valued list containing the object itself.

### Iteration Status

Thymeleaf also provides a way to **keep track of the iteration process by using the status variable** in `th:each` statement. For example, you can pass another [local variable](https://attacomsian.com/blog/thymeleaf-local-variables) next to `iter` to get the iteration statistics:

```markup
<div th:each="iter, stats : ${iterableObject}">
    <!-- do whatever you wan to do here -->
</div>
```

As you can see above, `stats` is the status variable that contains the following properties:

* `index`&mdash; The current iteration index, starting with 0.
* `count`&mdash; The number of elements processed so far.
* `size`&mdash; The total amount of elements in the iterated variable.
* `even/odd`&mdash; Check if the current iteration index is even or odd.
* `first`&mdash; Check if the current iteration is the first one.
* `last`&mdash; Check if the current iteration is the last one.

## Iterating through Map

Let us look at an example that uses the `th:each` attribute to loop through a Java `Map<String, User>` object:

```markup
<table>
    <thead>
    <tr>
        <th>#</th>
        <th>ID</th>
        <th>First Name</th>
        <th>Last Name</th>
        <th>Email</th>
        <th>Age</th>
        <th>Created</th>
    </tr>
    </thead>
    <tbody>
    <tr th:each="entry, stats : ${usersMap}" th:with="user=${entry.value}">
        <td th:text="${stats.index + 1}">1</td>
        <td th:text="${entry.key}">100</td>
        <td th:text="${user.firstName}">John</td>
        <td th:text="${user.lastName}">Doe</td>
        <td th:text="${user.email}">john.doe@example.com</td>
        <td th:text="${user.age}">27</td>
        <td th:text="${#dates.format(user.created, 'MMMM dd, yyyy')}">January 15, 2020</td>
    </tr>
    </tbody>
</table>
```

## Iterating through List

The following example demonstrates how you can loop through a Java `List<User>` object by using `th:each` attribute in Thymeleaf:

```markup
<div th:each="user, stats : ${usersList}">
    <div th:text="${stats.index + 1}">1</div>
    <div th:text="${user.firstName}">John</div>
    <div th:text="${user.lastName}">Doe</div>
    <div th:text="${user.email}">john.doe@example.com</div>
    <div th:text="${user.age}">27</div>
    <div th:text="${#dates.format(user.created, 'MMMM dd, yyyy')}">January 15, 2020</div>
</div>
```

## Iterating through Set

Iterating through a Java `Set<User>` collection is very much similar to a `List<User>` collection as shown below:

```markup
<div th:each="user, stats : ${usersSet}">
    <div th:text="${stats.index + 1}">1</div>
    <div th:text="${user.firstName}">John</div>
    <div th:text="${user.lastName}">Doe</div>
    <div th:text="${user.email}">john.doe@example.com</div>
    <div th:text="${user.age}">27</div>
    <div th:text="${#dates.format(user.created, 'MMMM dd, yyyy')}">January 15, 2020</div>
</div>
```

## Iterating through Array

The `th:each` attribute also accepts a Java array object as an iterable. Here is an example that shows how you can iterate a `User[]` array object in Thymeleaf:

```markup
<div th:each="user, stats : ${usersArray}">
    <div th:text="${stats.index + 1}">1</div>
    <div th:text="${user.firstName}">John</div>
    <div th:text="${user.lastName}">Doe</div>
    <div th:text="${user.email}">john.doe@example.com</div>
    <div th:text="${user.age}">27</div>
    <div th:text="${#dates.format(user.created, 'MMMM dd, yyyy')}">January 15, 2020</div>
</div>
```

## Conclusion

In this article, we looked at how iteration works in Thymeleaf templates. Thymeleaf provides `th:each` attribute that can be used to loop through different Java collection objects like `Map`, `List`, `Set` and array.

Thymeleaf offers powerful features that make it ideal for modern HTML5 Java-based web development. If you want to learn more about how to start working with Thymeleaf in Spring Boot, check out the [this guide](https://attacomsian.com/blog/spring-boot-thymeleaf-example).