Of course! Installing Java on Ubuntu is a common task. There are a few ways to do it, each suited for different needs.

Here’s a complete guide covering the most popular methods, from the easiest to the most flexible.

Quick Answer: The Easiest Way (Recommended for Most Users)

This method uses apt to install a standard OpenJDK package. It's simple, managed by the system, and integrates well with other Ubuntu tools.

1. Update your package list:

   sudo apt update

2. Install the default JDK: The default-jdk package is a "meta-package" that will automatically install the latest Long-Term Support (LTS) version of OpenJDK available in your Ubuntu repository. This is the best choice for general development.

   
   （图片来源网络，侵删）

   sudo apt install default-jdk

3. Verify the installation:

   java -version
   javac -version

   You should see output similar to this (the version number may vary):

   openjdk version "17.0.8" 2025-07-18
   OpenJDK Runtime Environment (build 17.0.8+7-Ubuntu-0ubuntu122.04)
   OpenJDK 64-Bit Server VM (build 17.0.8+7-Ubuntu-0ubuntu122.04, mixed mode, sharing)

Detailed Guide: Different Methods & Versions

The "Quick Answer" is great, but you might need a specific version or want to use a different distribution. Here are the details.

Method 1: Using apt (The System Package Manager)

This is the method used in the quick answer. It's reliable and handles dependencies for you.

Step 1: Update Package Lists Always start by updating your local package index.

sudo apt update

Step 2: Choose a Java Version to Install

You have two main options:

Option A: Install the Default (Recommended) This installs the latest LTS version (e.g., OpenJDK 17 or 11) that the Ubuntu maintainers have tested and approved.

sudo apt install default-jdk

Option B: Install a Specific Version If you need a specific version for compatibility (e.g., for an older project), you can install it directly.

• To see available versions:

  apt search openjdk | grep 'openjdk-[0-9]' | head -20

  This will show you available packages like openjdk-8-jdk, openjdk-11-jdk, openjdk-17-jdk, etc.

• To install a specific version (e.g., OpenJDK 17):

  sudo apt install openjdk-17-jdk

Step 3: Set the JAVA_HOME Environment Variable Many Java-based tools (like Maven, Tomcat, Spring Boot) require the JAVA_HOME environment variable to be set.

1. Find the Java installation path: The path is usually /usr/lib/jvm/java-VERSION-openjdk-amd64. You can find it with this command:

   sudo update-java-alternatives --list

   The output will look something like this:

   java-1.11.0-openjdk-amd64   1111       /usr/lib/jvm/java-1.11.0-openjdk-amd64
   java-1.17.0-openjdk-amd64   1171       /usr/lib/jvm/java-1.17.0-openjdk-amd64
   java-1.8.0-openjdk-amd64    1081       /usr/lib/jvm/java-1.8.0-openjdk-amd64

   Note the path for your desired version (e.g., /usr/lib/jvm/java-1.17.0-openjdk-amd64).

2. Set JAVA_HOME for your current session:

   export JAVA_HOME=/usr/lib/jvm/java-1.17.0-openjdk-amd64

   Note: This is temporary and will be reset after you reboot.

3. Make JAVA_HOME permanent: Add the export line to your shell's profile file (e.g., ~/.bashrc for Bash).

   echo 'export JAVA_HOME=/usr/lib/jvm/java-1.17.0-openjdk-amd64' >> ~/.bashrc
   source ~/.bashrc # Apply the changes to your current terminal

4. Verify JAVA_HOME:

   echo $JAVA_HOME

Method 2: Using SDKMAN! (The Developer's Choice)

SDKMAN! is a popular command-line tool for managing multiple versions of SDKs on Unix-based systems. It's the best choice if you frequently switch between Java versions.

Step 1: Install SDKMAN! Open a new terminal and run this command:

curl -s "https://get.sdkman.io" | bash

Follow the on-screen instructions. It will ask you to open a new terminal window to complete the installation.

Step 2: Install Java with SDKMAN! Now you can easily install any version of Java (including Oracle's JDK and OpenJDK).

• List available Java versions:

  sdk list java

• Install a specific version (e.g., OpenJDK 17.0.8):

  sdk install java 17.0.8-tem

  The -tem suffix stands for Temurin, which is a build of OpenJDK.

• Switch between installed versions:

  # Set a version as the default
  sdk default java 17.0.8-tem
  # Or just use it for the current session
  sdk use java 11.0.20-tem

• Verify the installation:

  java -version
  sdk current java

Method 3: Using the Official Oracle Website

This method is useful if you need the proprietary Oracle JDK, which has different licensing terms and might offer slightly different performance or features.

Step 1: Download the JDK

1. Go to the Oracle Java SE Development Kit Downloads page: https://www.oracle.com/java/technologies/downloads/
2. Accept the license agreement.
3. Select the .tar.gz archive for Linux x64.

Step 2: Install the JDK

1. Move the downloaded file to a convenient location, like /opt.

   # Replace 'jdk-17.0.8_linux-x64_bin.tar.gz' with your actual filename
   sudo mv ~/Downloads/jdk-17.0.8_linux-x64_bin.tar.gz /opt/

2. Navigate to the /opt directory and extract the archive.

   cd /opt
   sudo tar -xzf jdk-17.0.8_linux-x64_bin.tar.gz

3. Create a symbolic link for easier version management.

   sudo ln -sfn jdk-17.0.8 jdk

Step 3: Set Environment Variables This is similar to the apt method but you must do it manually.

1. Create a file for the environment variable:

   sudo nano /etc/profile.d/java.sh

2. Add the following lines to the file:

   export JAVA_HOME=/opt/jdk
   export PATH="$PATH:$JAVA_HOME/bin"

   Save the file (Ctrl+O, Enter) and exit (Ctrl+X).

3. Apply the changes:

   source /etc/profile.d/java.sh

4. Verify the installation:

   java -version
   echo $JAVA_HOME

Summary: Which Method Should You Use?