Ubuntu for mobile (Android) Java development

Posted on April 20, 2025 by kuperusm

This blog is about setting up a proper Linux Ubuntu environment to use when developing mobile applications for Android. Goal is to use 100% Java using JavaFX.

Some while ago, my laptop crashed enormously. Luckily, it also had a SSD drive which still functioned. Here are some steps I took to get this laptop up and running for mobile Java development running Ubuntu.

First step is to goto https://ubuntu.com/download/desktop and download the iso image. Then proceed to https://rufus.ie/en/ to get the (portable) version of Rufus. Format a USB stick, put the iso image on the stick using Rufus. Actually, https://phoenixnap.com/kb/install-ubuntu-24-04 is a great guideline to install Linux. Most difficult part for me was to get my laptop to boot from USB (as you can imagine that should be quite easy, you understand installing Linux is easy).

Install some java distributions:

apt install openjdk-17-jre-headless
apt install openjdk-21-jre-headless
apt install openjdk-17
apt install openjdk-21

Of course, download IntelliJ from https://www.jetbrains.com/idea/download/?section=linux and install it for example in /pub/software (and create a symbolic link called ‘idea’ to it).

Not really necessary, but sometimes useful, I installed SQL Developer (choose other platforms and just download the zip version). I’ve unpacked it in /pub/software/sqldeveloper. To get it to work using Java 17:

vi /pub/software/sqldeveloper/sqldeveloper/bin/sqldeveloper.conf

And put this on the second or third line

SetJavaHome /usr/lib/jvm/java-17-openjdk-amd64

The mentioned Java versions are for many reasons useful to have present on your system, but to develop mobile applications on your system, I use GraalVM with Gluon to build native images you can deploy and run on your phone. It is my experience that it’s a very delicate process to get all your add-ons versions aligned properly. So, next step is to goto https://github.com/gluonhq/graal/releases and download some latest stable and latest dev versions.

Besides the GraalVM with Gluon builds, it’s also useful to have a GraalVM JDK present (without Gluon), use https://github.com/graalvm/graalvm-ce-builds/releases for this. I’ve downloaded and extracted them in /pub/software.

Besides the JDK, it’s also required to download Android NDK (for C or C++ usage) and the Android SDK (because I don’t want to use Android Studio). I’ve downloaded them to /pub/android from https://developer.android.com/ndk/downloads and https://developer.android.com/studio/index.html#command-line-tools-only

When you’ve installed your favorite IntelliJ version, it comes with a Maven version (mine has 3.9.9 shipped), maybe download the 3.8.8 version as well from https://dlcdn.apache.org/maven/maven-3/3.8.8/binaries/ and put it in /pub/software. It might look like the following now.

Some packages needed for JavaFX in the future:

apt-get install libfreetype6-dev
apt-get install libgtk-3-dev

I use the following startup script to launch IntellilJ


#!/bin/bash
export M2_HOME="/pub/software/idea/plugins/maven/lib/maven3"
export GRAALVM_HOME="/pub/software/graalvm-gluon-23"
export JAVA_HOME="/pub/software/graalvm-gluon-23"
export ANDROID_NDK="/pub/android/ndk"
export ANDROID_SDK="/pub/android/sdk"
export ANDROID_HOME="/pub/android/sdk"
export ANDROID_SDK_ROOT="/pub/android/sdk"
export ANDROID_NDK_ROOT="/pub/android/ndk"

# export AR="aarch64-linux-android-ar"
# export CC="aarch64-linux-android30-clang"
# export CXX="aarch64-linux-android30-clang++"

export PATH="$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64/bin:$ANDROID_HOME/platform-tools:$ANDROID_HOME/cmdline-tools/latest/bin:$GRAALVM_HOME/bin:$M2_HOME/bin:$ANDROID_NDK:$ANDROID_SDK:$PATH"

cd ~/.m2
rm settings.xml
ln -sf $M2_HOME/conf/settings.xml settings.xml

cd /pub/software/idea/bin
./idea

The AA CC and CXX exports are necessary when you want to compile to native libraries. You’ll also notice the link from ~/.m2 to the Maven settings. This because IntelliJ sometimes resets the Maven settings back to ~/.m2

If you start IntelliJ using this script, open a terminal and type the following:

native-image --version
mvn -version
java -version

When upgrading any part of your setup, make sure to keep the old versions and create a new startup script. Using this method, you can be sure to build the newer version of your mobile app alongside a current version which works.

First step is actually get it to work on your mobile phone, that’s the difficult one. After that, nothing is holding you back.

Automatically reload / renew java cacerts in keystore

Posted on August 30, 2023 by kuperusm

In our current project we have a Nexus server as artifactory repository manager. Setup is not entirely finished and one drawback is that the certificate is only valid for 3 days.

The following script downloads the certificate and uses keytool to import the certificate only when it’s a new one (using the same alias)

#!/bin/bash
true | openssl s_client -connect nexus.mycompany.com:443 2>/dev/null | openssl x509 > ~/Downloads/nexus-crt.crt
DIFF=$(diff ~/Downloads/nexus-crt.crt ~/Downloads/nexus.mycompany.com.crt)
if [ "$DIFF" ]
then
   echo "Reloading Nexus certificate"
   cp ~/Downloads/nexus-crt.crt ~/Downloads/nexus.mycompany.com.crt
   cd ~/.sdkman/candidates/java/current/bin
   ./keytool -delete -alias nexus-crt -cacerts -storepass changeit
   ./keytool -importcert -noprompt -trustcacerts -cacerts -alias "nexus-crt" -file ~/Downloads/nexus.mycompany.com.crt -storepass changeit
   cd -
fi

If you want to display the certificates enddate:

echo "cert enddate: cat ~/Downloads/nexus-crt.crt | openssl x509 -noout -dates | tail -1 | sed 's/[^ ]*=//' "

gitlab git mvn pull all clean all

Posted on March 30, 2023 by kuperusm

Suppose you have a directory /pub/gitlab with all your git projects, but also a logs directory which can be skipped.

user@server:~$ cat > cleanall cd /pub/gitlab for d in */ ; do log=$(basename $d) [[ $log =~ ^(logs)$ ]] && continue cd "$d" echo -n "$d : " mvn clean cd .. done

user@server:~$ cat > pullall cd /pub/gitlab for d in */ ; do log=$(basename $d) [[ $log =~ ^(logs)$ ]] && continue cd "$d" echo -n "$d : " git pull cd .. done

Offline install sqlcmd (SQL Server command line tool) on Linux CentOS

Posted on May 10, 2022 by kuperusm

To install sqlcmd on Linux CentOS try to get hold on the following rpm’s :

unixODBC from CentOS: http://mirror.centos.org/centos/7/os/x86_64/Packages/
file: unixODBC-2.3.1-14.el7.x86_64.rpm

msodbcsql from Microsoft: https://packages.microsoft.com/rhel/8/prod/
file: msodbcsql18-18.0.1.1-1.x86_64.rpm

mssql-tools from Microsoft: https://packages.microsoft.com/rhel/7.3/prod/
file: mssql-tools18-18.0.1.1-1.x86_64.rpm

Now run:
sudo yum localinstall unixODBC-2.3.1-14.el7.x86_64.rpm
sudo yum localinstall msodbcsql18-18.0.1.1-1.x86_64.rpm
sudo yum localinstall mssql-tools18-18.0.1.1-1.x86_64.rpm

Accept license when asked and you’re done hopefully . Add to the path (in .bashrc):
export PATH=/opt/mssql-tools18/bin:$PATH

If you’re behind a firewall and your database instance is on port nnnn

sudo iptables -A INPUT -p tcp --dport nnnn -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT sudo iptables -A INPUT -p udp --dport nnnn -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT

Now try:
sqlcmd -S tcp:[hostname],[port] -U [username] -P [password]
or
sqlcmd -C -S tcp:[hostname],[port] -U [username] -P [password]
like
sqlcmd -C -S tcp:some.address.com,50001 -U john -P doe