How do I install openjdk 7 on Ubuntu 16.04 or higher?

I would like to upgrade my main system to 16.04, but I work on projects that require OpenJDK 7.

Apparently it is not available from a trivial apt-get install openjdk-7-jdk. Only versions 8 and 9 are listed in the repository.

Can anyone point me to instructions on how to install it?

Security Warning

Packages in the PPA mentioned below are not updated with security patches to Java. Do not use in production; see alternative answers instead.

At time of writing, the last upload for OpenJDK 7 was done '2016-04-22' with version 7u95 and still available as 'latest', where Ubuntu 14.04 has been updated to 7u181.

UPDATE : ALTHOUGH THIS IS THE MOST VOTED ANSWER ITS PROBABLY NOT THE ONE YOU WANT TO USE IN 2018 DUE TO LACK OF SECURITY UPDATES BY THIS PPA.

I found the following instructions which worked for me :

sudo add-apt-repository ppa:openjdk-r/ppa  
sudo apt-get update   
sudo apt-get install openjdk-7-jdk  

This defines the “PPA for OpenJDK uploads (restricted)” as an additional package repositiory, updates your information, and installs the package with its dependencies (from that repository).

Edit 22-Jul-2019: This answer currently does not work. The below referenced JDK packages are no longer available on Debian Experimental. In any case, they lagged behind Ubuntu Trusty's packages which contained more recent security updates. Please refer to the other answers until this can be resolved (sorry, no ETA).

It does not look like the maintainer of openjdk-r/ppa will be updating the openjdk-7 package beyond version 7u95-2.6.4-3. That package's description "Copied from debian experimental in Primary Archive for Debian GNU/Linux" gives us a clue about how to handle this ourselves, though.

Option 1: Manual Installation

1. Download the packages intended for your architecture:
   (for most users, this means amd64 if 64bit, or i386 if 32bit Ubuntu is installed)

   • openjdk-7-jdk
   • openjdk-7-jre
   • openjdk-7-jre-headless
   • libjpeg62-turbo
   • libfontconfig1 (only Ubuntu 17.10 and earlier; see note at bottom)
   • fontconfig-config (only Ubuntu 17.10 and earlier; see note at bottom)

2. (Attempt to) install the packages using dpkg:

   Ubuntu 17.10 and earlier:

   sudo dpkg -i openjdk-7-* libjpeg62-turbo* libfontconfig1* fontconfig-config*
   

   Ubuntu 18.04 and later:

   sudo dpkg -i openjdk-7-* libjpeg62-turbo*
   

3. Check the output from dpkg. If there were dependency problems – which is likely – you will see the following (with your architecture substituted for amd64):

   Errors were encountered while processing:
   openjdk-7-jre:amd64
   openjdk-7-jre-headless:amd64
   openjdk-7-jdk:amd64

   If there were no dependency issues, great, you're done, skip to #4. Otherwise, if you need to resolve some dependency issues, this is handled with:

   sudo apt install -f
   

   Notice, there is no need to re-run dpkg after letting apt resolve dependencies. It will automatically finish installation of the openjdk packages.

4. Update java alternatives. You can view all installed java versions with update-java-alternatives --list. To activate OpenJDK Java 1.7, run:

   sudo update-java-alternatives -s java-1.7.0-openjdk-amd64
   

   You may notice an error about the IcedTeaPlugin.so plugin being unavailable. This isn't a real concern for developers working with the JDK.

5. Verify java is working:

   java -version
   

   which should output something similar to:

   java version "1.7.0_161"
   OpenJDK Runtime Environment (IcedTea 2.6.12) (7u161-2.6.12-1)
   OpenJDK 64-Bit Server VM (build 24.161-b01, mixed mode)

Option 2: Automatic Installation (including updates with apt)

Pinning can be utilized to install and update openjdk-7-jdk and its dependencies from Debian repositories.

1. Create a pinning file that tells apt to only consider packages that interest us (we certainly don't want our entire Ubuntu distribution "upgraded" with Debian experimental packages).

   Create file /etc/apt/preferences.d/debian with the below contents. You'll need superuser privileges, so use one of sudo vim, sudo nano, gksudo gedit, etc.

   Package: *
   Pin: release o=Debian,n=experimental
   Pin-Priority: -1
   
   Package: *
   Pin: release o=Debian,n=sid
   Pin-Priority: -1
   
   Package: openjdk-7-jdk
   Pin: release o=Debian,n=experimental
   Pin-Priority: 500
   
   Package: openjdk-7-jre
   Pin: release o=Debian,n=experimental
   Pin-Priority: 500
   
   Package: openjdk-7-jre-headless
   Pin: release o=Debian,n=experimental
   Pin-Priority: 500
   
   Package: libjpeg62-turbo
   Pin: release o=Debian,n=sid
   Pin-Priority: 500
   

   For Ubuntu 17.10 and earlier, also append the following (and see note at bottom):

   Package: libfontconfig1
   Pin: release o=Debian,n=sid
   Pin-Priority: 500
   
   Package: fontconfig-config
   Pin: release o=Debian,n=sid
   Pin-Priority: 500
   

2. Install the Debian keyring:

   sudo apt install debian-archive-keyring
   

   Note: while this is the simplest method of adding the debian keyring, it may not be up to date. Check for output like the following when running apt update in step 4:

   W: GPG error: http://cdn-fastly.deb.debian.org/debian experimental InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010
   E: The repository 'http://httpredir.debian.org/debian experimental InRelease' is not signed.

   If you see this error, then manually add the necessary keys with:

   sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 8B48AD6246925553
   sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 7638D0442B90D010
   

   where 8B48AD6246925553 and 7638D0442B90D010 should match the pubkeys you see in the warning message.

3. Add the needed repositories:

   sudo add-apt-repository 'deb http://httpredir.debian.org/debian experimental main'
   sudo add-apt-repository 'deb http://httpredir.debian.org/debian sid main'
   

   Why not use a stable Debian repository? You'll run into unsatisfiable dependencies with Debian stable. The experimental (for openjdk-7) and sid (for libjpeg62-turbo, libfontconfig1, and fontconfig-config) repositories are more lenient with dependency versions.

4. Update apt cache (expect this to take a while since Debian's package lists are big):

   sudo apt update
   

5. Install openjdk-7-jdk:

   sudo apt install openjdk-7-jdk
   

6. Update java alternatives. You can view all installed java versions with update-java-alternatives --list. To activate OpenJDK Java 1.7, run:

   sudo update-java-alternatives -s java-1.7.0-openjdk-amd64
   

   You may notice an error about the IcedTeaPlugin.so plugin being unavailable. This isn't a real concern for developers working with the JDK.

7. Verify java is working:

   java -version
   

   which should output something similar to:

   java version "1.7.0_161"
   OpenJDK Runtime Environment (IcedTea 2.6.12) (7u161-2.6.12-1)
   OpenJDK 64-Bit Server VM (build 24.161-b01, mixed mode)

fontconfig notes

libfontconfig1 and fontconfig-config must be upgraded to 2.12 or later on Ubuntu 17.10 and earlier. The update packages from Debian do not contain Ubuntu's customizations, so some applications display ugly fonts with these packages installed; e.g. Charles Web Debugging Proxy. Depending on the programs you use, you may or may not be affected by this problem.

You can download a OpenJDK 7 from Azul which may fit your needs. They both have a DEB (for the package system) and a ZIP distribution. I have only worked with the ZIP distribution.

http://www.azul.com/downloads/zulu/zulu-linux/

Use containers

This is a universally valid answer on how to run <outdated> removed software on <current> Ubuntu: containerize your application.

For example, use Docker and an older Ubuntu base image in which the software you're looking for is still available/maintained.

It also works the other way around; try out the software on a newer or even other Linux distribution on your currently running stable Ubuntu.

Example for Java 7 using Ubuntu 14.04

1. Install Docker - Docker CE free version is fine. See for example https://docs.docker.com/install/linux/docker-ce/ubuntu/ or use the docker.io package in recent Ubuntu versions shipped.

2. In an empty folder, create a file Dockerfile:

   FROM ubuntu:trusty
   RUN apt-get update \
       && apt-get install -y \
           openjdk-7-jdk \
       && rm -rf /var/lib/apt/lists/*
   
   ENTRYPOINT ["/usr/bin/java"]
   

   Add more packages in that command if you need that.

3. In that folder, run:

   docker build -t gertvdijk/java7 .
   

4. Run a command inside a single-use-container using that Java 7 image:

   E.g. java -version:

   docker run --rm -it gertvdijk/java7 -version
   

   Output:

   java version "1.7.0_181"
   OpenJDK Runtime Environment (IcedTea 2.6.14) (7u181-2.6.14-0ubuntu0.1)
   OpenJDK 64-Bit Server VM (build 24.181-b01, mixed mode)
   

5. Optionally, create a wrapper for convenience.

   • Create a file /usr/local/bin/java7-in-docker with contents:

     #!/usr/bin/env sh -e
     
     DOCKER_IMAGE=gertvdijk/java7
     PWD="$(pwd)"
     
     exec docker run \
       --rm -it \
       -v ${PWD}:${PWD} \
       -v "/etc/passwd:/etc/passwd:ro" \
       -v "/etc/group:/etc/group:ro" \
       --user "$(id -u):$(id -g)" \
       --workdir "${PWD}" \
       "${DOCKER_IMAGE}" \
       $@
     

     This will make the current working directory available inside the container - not your whole filesystem, and it will impersonate your local user account in the container namespace.

   • Mark it as executable:

     sudo chmod +x /usr/local/bin/java7-in-docker
     

6. Run your Java 7 transparently, like this:

   java7-in-docker -jar relative/path/to/some.jar