How to Download and Compile Solr 6 in Eclipse

Overview

• Download and install the Oracle Java SE JDK
• Download and Install Eclipse
• Download and Install Apache Ant
• Download Solr source code
• Prepare Solr source code for Eclipse environment
• Importing and compiling Solr source in Eclipse
• Using the Build.xml files in the Project

Download and install the Oracle Java SE JDK

1. For Solr 6.0.0, you need at least Java SE 8
2. I chose to install the Windows x64 product
3. Make sure that java is accessible from the command line
1. Open a new command window
2. type: java -version

You should see something like:
java version "1.8.0_91"
Java(TM) SE Runtime Environment (build 1.8.0_91-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.91-b14, mixed mode)

The JDK automatically installs the JRE, so you don't need to install them separately.

Download and Install Eclipse

1. Go to the Eclipse download page and download the version that's right for you (I chose 64-bit Eclipse IDE for Java Developers)
   NOTE: If you installed the 64-bit JDK, you'll need to install the 64-bit version of Eclipse.  If you installed the 32-bit version, you'll need to download the 32-bit version of Eclipse.
2. All you need to do in order to install Eclipse is to extract it to where you want it to live--I chose D:\eclipse64
3. Open that folder and double-click eclipse.exe
4. When asked to set the workspace, I chose D:\eclipse_workspace

Download and Install Apache Ant

1. Download page
2. I downloaded the .zip archive
3. I chose to extract it to C:\Apache\ant-1.9.7
4. Add Apache Ant's bin directory to your PATH environment variable (C:\Apache\ant-1.9.7\bin)

Download Solr source code

1. I used this link to download the tgz source file (they didn't have a ZIP version of the source at this time).  If that link isn't available, then go to the Solr latest redirect page.
2. Since I'm on Windows, I needed to download 7-Zip (I used the 64-bit version)
3. Extract the source (I will use D:\solr, which should generate a D:\solr\solr-6.0.0 folder)

Prepare Solr source code for Eclipse environment

1. Open this folder in Windows Explorer
2. Shift + Right-Click in the whitespace inside the folder and click Open command window here (or open a command window and cd to your new solr-6.0.0 folder)
3. ant eclipse
4. At this point, Solr should be preparing the source for use in Eclipse.  You should see something like this:
   BUILD SUCCESSFUL
   Total time: 22 seconds

Importing and compiling Solr source in Eclipse

1. Go back to Eclipse
2. File > Import...
3. Expand General and select Existing Projects into Workspace
4. Click Browse... next to Select root directory and select the solr root directory (where you extracted the source tgz file)
5. It should find the solr project and list it in the Projects list below.  Make sure it's selected and click Finish
6. Eclipse should automatically start building the project (you should see an indicator in the bottom-right corner)
7. While it's building, click on the Workbench icon at the top-right corner
8. You should see the Package Explorer on the right-hand side
9. At the bottom, middle, you should see a Problems tab.  Click on it if it's not the one in focus.
   As it was compiling, I saw a few items get put in there, but they went away by the time it stopped compiling and I was left with 11,156 warnings and 0 errors.

Eclipse should be happy with the compile results, but you will want to do a bit more than Eclipse does when it first imports the code.  Solr makes a lot of use out of Apache Ant, which operates on the build.xml file.

Using the build.xml files in the Project

1. Expand the solr root folder in the Package Explorer and select the build.xml file
2. Right-click the build.xml file > Run As > Ant Build...
3. Uncheck the -projecthelp [default] item at the top of the list
4. This is how you can trigger the ant targets in Eclipse.  Let's trigger the real compile (as far as solr is concerned).
5. Check the compile target and click Run
6. It will probably take a few minutes before you see the BUILD SUCCESSFUL message
7. Now let's use build.xml in Eclipse to build the server
8. Expand the solr subfolder and right-click that build.xml (note that this is a subfolder off of the root source folder) > Run As > Ant Build...
9. Uncheck the usage [default] target
10. Check server and click Run
11. That should build the server, which you can then run and index files.
    Check out this article I wrote about this if you want to learn more (you can skip the first part, since you've essentially set up your environment).

Conclusion

Now you're in a good position to get started in development in the Solr community, although you will want to use the git repository to get the latest version.  Getting started can be a bit tough, so starting with a known good source is important, as you can scratch your head for days not knowing why the code doesn't compile--when it just so happened to be a bad check-in.  That's one of the reasons I started by downloading the 6.0.0 source, because it's quite likely that that code compiles.

I owe a huge thank-you to @elyograg from the #solr chat room, who walked me through my Eclipse woes!  It seems as though I was doing everything wrong and this guy set me straight.

As always, make sure you know the answer to life's most important question.  After reading that, enjoy a nice break and watch this free movie on YouTube.