How to install a .jar file

You must installed java on your system to install .jar files.Syntax to install .jar files was,

java -jar packagename.jar

In this case,you have Minecraft.jar file,so type the below command in terminal

java -jar Minecraft.jar 

A .jar file is a Java Programming Language file. You can do this, since it's Minecraft:

1. Create a new folder in your user folder. (It can also be recognized as a "~".)

2. Move Minecraft and an icon (call it "Minecraft" and make sure it's a .png, and if not, convert it using an online tool.) to a folder you will keep it in. Use ~/.apps/Minecraft, for the sake of usage.

3. Make a file, on your desktop. Create a new file, name it "Minecraft.desktop". More info here. Copy-and-paste this after you open it with a text editor:

   [Desktop Entry]
   Name=Minecraft
   Exec=java -jar ~/.apps/Minecraft/Minecraft.jar
   Icon=~/.apps/Minecraft/Minecraft.png
   Type=Application
   Categories=Game;
   

4. Do this in terminal:

   sudo apt-get install default-jre
   chmod +x ~/.apps/Minecraft/Minecraft.jar
   chmod +x ~/Desktop/Minecraft.desktop
   

5. Now, double-click and play!