Install Java Runtime Environment (JRE)
Daffodil requires Java 8. If you do not already have the Java Runtime Environment, it can be downloaded for free at https://java.com/en/download/.
Obtain The Latest Daffodil Release
Visit the Daffodil Artifacts Page to download the latest Daffodil stable or development releases.
Run Daffodil
After you have downloaded the latest Daffodil Release, you'll want to uncompress the files into a suitable location on your machine. The uncompressed directory contains a bin directory that contains two scripts: daffodil.bat for Windows, and daffodil for Linux. These files must be executed on the command line. See the Examples page to see how to execute and use the Daffodi CLI, and the Command Line Interface page for the in depth usage.
Use Daffodil via Calling it from Your Own Java
Daffodil has a Java API. Attached to this page is a helloWorld.zip which is the Daffodil/DFDL version of a hello world program. It parses some data "Hello world! " into XML and unparses it back, calling Daffodil from the Java API. It's is self contained so just unzip it. You need sbt 0.13 to build it, and this will pull daffodil's jars and everything else they depend on to your machine automatically. If you have sbt then just typing the command "sbt run" in the root directory where you unzipped this will do all of it. Look in the src/main/java/HelloWorld.java file to see how the Java API works.