The File Extensions Database

.J File Extension

  • Developer by: Oracle
  • Category: Developer Files
  • Format: Text

What is an .J file?

.J is Java Source File

Contains program source code written in the Java programming language; may include the source code for a complete program or may be one of many files referenced by a Java programming project.

Java source files most often have a .JAVA extension.

Programs that open Java Source File
File Viewer Plus
Oracle Java Virtual Machine
Eclipse IDE for Java Developers
Oracle Java Virtual Machine
Eclipse IDE for Java Developers
Oracle Java Virtual Machine
Eclipse IDE for Java Developers
File Type 2 JAR Archive
Category: Compressed Files

Compressed file archive created with JAR, the successor to the ARJ file compression program (which created .ARJ files); JAR is available in a 16-bit DOS version and a 32-bit Windows version.

Not related to the .JAR format, which is a Java Archive.

File Type 3 JPEG Image
Category: Raster Image Files Format: Binary

Compressed graphic that uses .JPEG image compression; may contain thousands of colors, which makes it a good format for storing digital photos; can use different levels of compression, but the more compression is used, the lower the quality of the resulting image.

Most JPEG files have a .JPG extension.

Programs that open JPEG Image
Any Web browser
Any Web browser

How to solve problems with J files

  • Associate the J file extension with the correct application. On :
    Windows: Right click on any J file and then click "Open with" > "Choose another app". Now select another program and check the box "Always use this app to open *.J files". Mac: Right click (or Ctrl-click) the J file, then click "Open with" > "Other...". Then choose another program and check the "Always Open With" box. Linux: Right click on the file, and select "Open with" and choose another program. iPhone: Tap the file. If you do not see an app to open the file, then tap Share "Share" and choose an app. Alternatively, save the file. Then open the Files app Files app. There long-press on the file, then release your finger. You will see a black menu bar. Then tap "Share" and select an app. Android: Tap the Settings icon on your smartphone, then tap on the Apps section. There tap the Options icon in the top right-hand corner of the screen to change the default apps.
  • Update your software that should actually open .J is Java Source File. Because only the current version supports the latest J file format. Search, therefore, e.g. on the Oracle manufacturer website after an available .J is Java Source File update.
  • To make sure that your J file is not corrupted or virus-infected, get the file again and scan it with antivirus software.