File Extension .Jar

The file extension JAR stands for “Java Archive” – a program that is commonly used to package and dispense Java meta-data and classes in different development environments. Aside from this type of JAR file, information on Mozilla Firefox Web Browser’s or Mozilla Thunderbird Email client’s themes and add-ons may also be stored in JAR files.

JAR files are compressed files over which aside from the Java classes and resources, it also contains the manifest file which will tell the program using the JAR file how to handle the file. A manifest file inside a JAR file may also contain links to several other JAR files that are needed for the specific JAR file to work. JAR files usually support digital signaling wherein a mark or a signature is added to the manifest file when the JAR file is opened and decompressed. This will help users to detect alterations of the contents of the file and therefore keep the file safe and secure to use as some third-party users may inject malicious information in the JAR file which could infect the receiver’s computer system.

JAR files can only be executed in a computer system where there is an installed JRE or Java Runtime Environment. Users must take extra precautions though before opening files with a JAR extension as it may contain malicious information. Users must make sure they know where the JAR file is from and make sure that the source is safe. A Java Runtime Environment can be made available to Windows, Mac, Linux and Solaris platforms. If the JRE is installed in the system, a JAR file can be opened in any Java-supported web browser. Users can also try to decompress and extract the contents of a JAR file using different compression and archiving tools and utilities but this isn’t really recommended since the content will just be unreadable and therefore useless for humans.

The following programs can read and/or open JAR files: