How do we run a Java application without an IDE?
After finishing developing and testing in an IDE, before distributing it for deployment, it is good to test the application outside of the IDE.
A Java application is built into a JAR file. The JAR file will run from the command line.
1. JAR (Java Archive) File
A JAR (Java Archive) file is a compressed package that is executable by Java Runtime Environment (JRE). Multiple Java class files can be bundled into a single archive file with file extension
2. Creating the JAR File
Once a Java project has been completed inside an IDE, start to build the project and create a JAR file.
Specify the Main Class
Be sure to have the main class specified in the project. To do so, right click the project name under the Projects tab. Select
Set Configuration and then
Customize. The value in the field
Main Class should be a class that has the main method.
Build the Project
Right click the project name under the Projects tab. Select
Clean and Build. Or in the top menu bar,
Clean and Build Project.
The following change will be made during the build:
Two new folders,
dist, are added to the project folder (referred to as the PROJECT_HOME folder).
All the sources are compiled into
.classfiles, which are placed into the PROJECT_HOME\build folder.
A JAR file is created inside the PROJECT_HOME\dist folder.
Beside the JDK, if any libraries have been specified for the project, a
libfolder will be created in the folder
dist. The libraries will be copied into
manifest filein the JAR is updated to include entries that designate main class and any libraries that are on the project’s classpath.
Follow the instructions above, build a JAR file (inside the NetBeans) for Echo application (which is discussed in the post Java Review: Application.
After the build completes, navigate to the
PROJECT_HOME/dist folder. There are two files named
README.TXT contains the information about how to launch the application.
To read the content, open README.TXT in a text editor. Part of the content is copied below that are instructions of running the application.
To run the project from the command line, go to the dist folder and type the following:
java -jar "Echo.jar"
To distribute this project, zip up the dist folder (including the lib folder) and distribute the ZIP file.
4. Launching the JAR File
To run the application from the command line,
- Inside the
Navigate to the
dist folder and type the following command:
java -jar "Echo.jar" coffee data 12 anything better
- Outside of the
To run the application from the command line outside of the
dist folder, enter the full path (absolute path) to the jar file in the command:
java -jar "C:\PROJECT_HOME\dist\Echo.jar" coffee data 12 anything better
Windows uses back slashes. Other operating systems and Web use forward slashes.
5. Distributing the Project
As indicated in
READEME.TXT, to distribute the project,
Zip up the
distfolder (including the
libsubfolder if there is one)
ZIP fileto the people who should be the recipients.