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How to Fix “package org.apache.commons.lang does not exist” Error in Java

You can stop worrying if you have come across the following lines in a Java stack trace!

package org.apache.commons.lang does not exist

static import only from classes and interfaces

Although frustrating, this error is easy to fix once we understand the root causes and solutions.

Our Experts have put together this guide to help you resolve this issue.

An Overview:

• Understanding Apache Commons Lang
• Common Causes of the Error
• How to Resolve the Error
• 1. Add the Library Dependency
• 2. Download the JAR Manually (Standalone Projects)
• 3. Correct the Package Name
• 4. Verify IDE Configuration

Understanding Apache Commons Lang

Apache Commons Lang is a popular Java library that enhances standard Java capabilities with utility functions for string manipulation, object comparisons, concurrency, and more.

The library’s classes and methods are organized under the `org.apache.commons.lang3` package in modern versions (3.x and above). Older versions used `org.apache.commons.lang`. These differences in package names are often the source of confusion.

Common Causes of the Error

1. The `org.apache.commons.lang` package belongs to the Apache Commons Lang library. If this library is not added to our project dependencies, the Java compiler will throw the “does not exist” error.
2. Modern versions of the library (3.x and above) use the `org.apache.commons.lang3` package. If our code references `org.apache.commons.lang`, we may be using an outdated version or need to update our imports.
3. The library might not be correctly configured in the project’s classpath even if the library is downloaded. Without proper configuration, the compiler cannot locate the required classes.

How to Resolve the Error

1. Add the Library Dependency

Using a build tool like Maven or Gradle makes dependency management straightforward.

We need to add the following dependency to our `pom.xml` file for Maven:


<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version> <!-- Replace with the latest version -->
</dependency>


If we are using Gradle, we have to include this in our `build.gradle` file:

implementation 'org.apache.commons:commons-lang3:3.12.0' // Update version as needed

Save the changes and refresh your project. The build tool will automatically fetch and configure the required library in our classpath.

2. Download the JAR Manually (Standalone Projects)

We can manually download the Apache Commons Lang JAR file from this link for standalone projects without build tools.

https://commons.apache.org/proper/commons-lang/

1. First, download the latest JAR file.
2. Then, add it to the classpath. For example, compile the Java code with the following command:

   
javac -cp "path/to/commons-lang3-3.12.0.jar" YourClass.java


3. Correct the Package Name

Modern versions of Apache Commons Lang (3.x and above) use the package `org.apache.commons.lang3`. If our code references `org.apache.commons.lang`, we have to update our imports:


// Replace this
import org.apache.commons.lang.StringUtils;
// With this
import org.apache.commons.lang3.StringUtils;


This change ensures compatibility with the current library version.

4. Verify IDE Configuration

If we are using an Integrated Development Environment (IDE) like IntelliJ IDEA or Eclipse, ensure that:

• The library is added to the build path or dependencies section.
• Then, the project is refreshed to reflect changes in dependencies.
• Rebuild the project to ensure the compiler includes the library.

In IntelliJ IDEA:

• Go to File > Project Structure > Libraries and ensure the library is added.
• Then, click `Reload All Maven Projects` if using Maven.

In Eclipse, right-click the project, go to `Build Path > Configure Build Path,` and add the library under the `Libraries` tab.

[Need assistance with a different issue? Our team is available 24/7.]

Conclusion

The “package org.apache.commons.lang does not exist” error is a common issue caused by missing libraries, incorrect versions, or misconfigured classpaths. We can quickly resolve the issue by adding the Apache Commons Lang library through a build tool, updating package names, or fixing classpath configurations.

In brief, our Support Experts demonstrated how to fix the “package org.apache.commons.lang does not exist” Error in Java.