NOTE: This blog post was originally hosted on Klocwork's Android blog. At some point those posts may not continue to exist. I've made every attempt to preserve the original content with only formatting changes to fit this site.

by Eric Cloninger

Google released Android 4.3 (Jellybean) source to the AOSP repository a few weeks ago. Whenever this happens, I sync my build box against the AOSP sources. Then I spend some time going through the diffs and run a full Klocwork scan against the code, just to make sure no new problems surface.

I build several Android projects each week and I scan most with our tools. Within certain ranges, I know about how long the builds take and what the distribution of errors looks like. When I started the build for 4.3, I knew I could get on my bike, ride to the deli and grab a sandwich and still have enough time for a peaceful lunch on the patio outside my office.

Needless to say, I didn’t get to enjoy my sandwich as the log files showed the build process lasted less than 2 minutes. The culprit was the build scripts are too smart—they check that I have the correct version of Java installed.

Wait. I have the wrong version of Java installed? There’s only one version of Java that’s allowed with AOSP and that is Sun (Oracle) Java 1.6. There’s no way I would’ve replaced that. I checked java -version and, sure enough, it was Java 1.7.0.21-b11. How did that get in there?

Truth is, there’s no telling. I install and uninstall a lot of software on my build machine and I’m also impatient when it comes to looking at updates. Java 1.6 was still on the machine, it just wasn’t on the path. So, I used the wonderful update-java script that I mentioned in a previous post to set everything back to 1.6.

wget http://webupd8.googlecode.com/files/update-java-0.5b
chmod +x update-java-0.5b
sudo ./update-java-0.5b

I restarted the script and devoted my attention to the muffuletta on my table. I wasn’t two bites into the sandwich when the console window scrolled up, indicating it was finished. I went to the logs and discovered that the $JAVA_HOME value in my .bashrc had changed. I honestly have no idea how this happened.

# export JAVA_HOME=/usr/lib/jvm/java-6-oracle
export JAVA_HOME=/usr/lib/jvm/java-7-oracle

Maybe I sleep-walk, sleep-copy, sleep-paste, and sleep-edit.

I did what every developer does: I looked for a solution on StackOverflow. From this post, I whipped up a bash script that alerts me before anything else happens. I put this in my .bashrc with a note, but I also have it in the script I use to kick off an Android build.

#!/bin/bash
# Usage: checkjava.sh [java_version]
#    if no parameter, script assumes 1.6 (for Android JDK)
# Returns: 0 for successful match
#          1 for no Java or wrong Java
if [ $# -eq 0 ] ; then
  assume="1.6"
else
  assume=$1
fi
typeval=`type -p java`
if [[ -n $typeval ]] ; then
  _java=java
elif [[ -n "$JAVA_HOME" ]] && [[ -x "$JAVA_HOME/bin/java" ]];  then
  _java="$JAVA_HOME/bin/java"
else
  echo "Warning: Java not on PATH"
  exit 1
fi
if [[ "$_java" ]]; then
  version=$("$_java" -version 2>&1 | awk -F '"' '/version/ {print $2}')
  jver=${version:0:3}
  if [[ "$jver" != "$assume" ]]; then
	echo "Java version on PATH is $version"
	exit 1
  fi
fi
exit 0

Granted, the Android build system will detect this early on, but it takes a couple minutes of figuring out the dependencies before it does the work. I would rather know the moment I open a bash prompt that I may need to give my JDK settings some attention.

You may be wondering what connection the photo has to this article. Our marketing team expects a photo to go along with a blog post. I looked for images of coffee cups and spilled coffee from various stock photo sources, but it’s such a cliché (one I’ve already abused). I started looking through my own photos on flickr. This is a gleaner (wheat harvester) a few miles from my home in Oklahoma. Like this ancient piece of equipment, Java 6 is broken and needs to go into the sunset, but Android developers are stuck using it until the platform evolves.


Gleaner in Decay by Eric Cloninger, Creative Commons license (CC-BY-2.0) About the Author:

Eric got his start in electronics by disassembling radios at age 10 and putting them back together. Before he could legally drive, he was installing stereos in his friends' pickups. From there came obsessions with kites, basketball, girls, computers, tools, guitars, baseball, woodworking, photography, golf, and kayaking with varying degrees of success. Eric lives where there are few trees, little water, and no mountains, but he dreams...