When Saving As... type the name then .jpg and it will be saved as a jpg. However jpgs are pictures and if it dosent save as a jpg it might have some issues such as being too big of a file for a jpg,...
Java comes with an executable file called jar that's used to create java exicutible files. You can do this by using cmd. 1:You must make a java project with a java creating software like Intellij...
A java file contains the code you write. One java file contains one class so for example when I want to make a class called Person, the source code is saved in Person.java