How to Iterate Through a HashMap in JSP Using JSTL?

How to Loop Through a HashMap in JSP

Wanting to loop through a HashMap in JSP? It's easy, following the same principles as you would in normal Java code:

for (Map.Entry<String, String> entry : countries.entrySet()) {
    String key = entry.getKey();
    String value = entry.getValue();
    // ...
}

However, using scriptlets (raw Java code in JSP files) is considered poor practice. Instead, consider installing JSTL. Its tag lets you iterate over Maps, with each iteration returning a Map.Entry featuring getKey() and getValue() methods.

Here's a basic JSTL example:

<%@ taglib prefix="c" uri="jakarta.tags.core" %>

<c:forEach items="${map}" var="entry">
    Key = ${entry.key}, value = ${entry.value}<br>
</c:forEach>

Applying this to your specific case, you could solve it with:

<%@ taglib prefix="c" uri="jakarta.tags.core" %>

<select name="country">
    <c:forEach items="${countries}" var="country">
        <option value="${country.key}">${country.value}</option>
    </c:forEach>
</select>

To use ${countries} in EL, you'll need a Servlet or ServletContextListener to place it in the desired scope. For request-based scenarios, use the Servlet's doGet(). For application-wide constants, employ ServletContextListener's contextInitialized().

For further insights, check out these resources:

• [Iterate over elements of List and Map using JSTL tag](https://stackoverflow.com/a/26817162/14731)
• [How to iterate over a nested map in ](https://stackoverflow.com/a/6644134/14731)
• [How to iterate an ArrayList inside a HashMap using JSTL?](https://stackoverflow.com/a/17615711/14731)
• [Using special auto start servlet to initialize on startup and share application data](https://stackoverflow.com/a/1942639/14731)

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