Files that contain the .j file extension are most commonly used by the Java programming language. The J files that are used by this language contain the source code that has been written in Java. These files may contain the code for an entire software application or may consist of a single file that is referenced by another Java programming project.
The J files that are associated with JAVA are usually saved with the .java file extension, but the .j file extension can be used in lieu of the standard .java suffix.
The .j file extension is also used for the archive files that are created with the JAR archiving software.
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