How to Install Multiple Versions of Java on Ubuntu 20.04 LTS Linux (2025)

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How to Install Multiple Versions of Java on Ubuntu 20.04 LTS | Easily Switch Between Java Versions In this complete step-by-step tutorial, learn **how to install multiple versions of Java (JDK)** on **Ubuntu 20.04 LTS** and how to easily switch between them using Ubuntu’s built-in `update-alternatives` system. Whether you're a Java developer, backend engineer, or working with tools that require specific JDK versions (like Maven, Gradle, Tomcat, Jenkins, Android Studio, Hadoop, etc.), this guide will help you manage multiple Java installations without conflicts. Java development often requires switching between versions like **Java 8**, **Java 11**, **Java 17**, or **Java 21**, and this tutorial shows exactly how to install them cleanly and toggle between them using simple commands. --- ### **What You’ll Learn in This Video:** ✅ How to update your Ubuntu system ✅ How to install OpenJDK 8, 11, 17, and 21 ✅ How to check installed Java versions ✅ How to use `update-alternatives` to manage multiple JDKs ✅ How to set a default Java version ✅ How to switch between Java versions anytime ✅ How to set JAVA_HOME for each version ✅ How to verify your JAVA_HOME path ✅ How to remove or replace Java versions safely --- ### **Why You May Need Multiple Java Versions:** 🔹 Legacy applications requiring Java 8 🔹 New frameworks and tools using Java 17 or Java 21 🔹 Development and testing across different JVM versions 🔹 Working with multiple projects with different JDK requirements 🔹 Runni