Jar Launcher is the program in Mac OS X that launches Java JAR files into the Aqua/Java runtime environment when the JAR file is double clicked. Jar Launcher also launches a class in the same manner. Jar Launcher does not execute the Java files itself, rather it passes them to the Java Virtual Machine (JVM) with any appropriate parameters. Java programs without any GUI should be run from the command line as they may not properly execute without a pseudo terminal.