Some JAR files are executables and you can launch them if you have Java environment installed in your system. Some are however not and users may attempt a JAR to EXE conversion which is possible with conversion utilities like the jar2exe.
Found 2 different conversion types using the same filename extensions.
Conversion jar to exe type 1:
Convert from Compressed archive file package for Java classes and data to Program executable.
Multiplatform software - convert jar to exe on any platform
jar2exe is a program used to wrap, run, protect and enhance your java program into binary file for Windows, Linux and Mac OS X.
File type (from-> to)
Convert from jar file
Compressed archive file package for Java classes and data
to exe file
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned jar to exe. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Conversion jar to exe type 2:
Convert from Compressed archive file package for Java classes and data to Self-extracting compressed file archive.
Microsoft Windows software - convert jar to exe on Windows
A free file archiver developed by Igor Pavlov featuring higher compression ratios with LZMA and LZMA2 compression.
It is mainly available for Windows platform (for Mac and Linux are available command line tools) and is the primary program to handle 7z archives. However, also supports various compression file formats.
Packing / unpacking: 7z, XZ, BZIP2, GZIP, TAR, ZIP and WIM
Unpacking only: AR, ARJ, CAB, CHM, CPIO, CramFS, DMG, EXT, FAT, GPT, HFS, IHEX, ISO, LZH, LZMA, MBR, MSI, NSIS, NTFS, QCOW2, RAR, RPM, SquashFS, UDF, UEFI, VDI, VHD, VMDK, WIM, XAR and Z