JAR files (Java Archive) are used to package multiple Java source files that are part of a single Java program. Once a JAR file has been created by a programmer, the JAR file itself needs to be executed by the Java interpreter in order to run the Java program. There are several ways to run the JAR file, depending on the operating system of the computer and whether the JAR file is being run from a web browser.
1. Install Java. Java can be downloaded from the java.com link in Resources for most popular operating systems. Part of the Java installation process on some operating systems involves associating JAR files with the Java interpreter program. This means the operating system will automatically recognize JAR files as something that needs to be run by the Java interpreter program when double-clicked from a graphical environment.
2. If the JAR file is being run from a graphical environment, double-click on the JAR file to run it. On a Windows system, locate the JAR file by clicking the “Start” menu and then “Computer.” Navigate to the location of the JAR file. Then double-click the JAR file. The JAR file should run automatically.
3. If the JAR file is on a web page, click on the link to the file. After the JAR file is clicked from the web browser, it will either run or the browser will request permission to run the JAR file. When Java was initially installed, Java also modified the configuration of all installed web browsers to recognize JAR files.
4. If the JAR file is being run from the command line, change to the same directory as the JAR file and run it. Use the cd command to change to the correct directory. Once inside the correct directory, run “java -jar jar-filename” where jar-filename is the filename of the JAR file. This command tells the Java interpreter to execute the file as a JAR file. This is equivalent to double-clicking the JAR file in the graphical environment.