Jar Term

This app will run console based Java programs on an Android device. The jar files of the programs should be converted to dex files and loaded onto the sd card. This has been tested on a Nexus 7 (2013) tablet with Android Marshmallow 6.0.1 and an old Kyocera Event with Ice Cream Sandwich 4.04.

To select a file, click on the gear and "dex file" to load, and then click on "main class" to choose the main class. To run, click on the lightning icon to run. The back button brings up a choice dialog to halt the program or do the default back action.

Convert a jar file to dex with the dx program supplied with the Android SDK. The SDK can be found at the following website (the page end)
https://developer.android.com/studio/index.html

I convert it on windows with the command
dx --dex --output=myfile.dex --no-strict myfile.jar

To find the main class without the source code you can copy the file and replace with suffix with zip (e.g. copy myfile.jar to myfile1.jar and rename the latter to myfile1.zip). Then open the zip file and look for "MANIFEST.MF" which should be a text file with a line like "Main-Class: com.example.MyMainClass". If you have the 7zip program, use the command
sz x myfile.jar META-INFMANIFEST.MF -so 2>nul | findstr "Main-Class"

An example Java program is at
http://plover.net/~trikiw/images/Wumpus.dex