File Extensions (Java and C# Cross Reference Guide)

The customary primary source file extension for Java code is ".java" which could contain anywhere from a single class to the entire source code.

Other important files:

• .JAR - Java archive file (compressed code file). Archive that contains multiple Java files and is compressed using .ZIP compression; stores Java classes and metadata and may be digitally signed; runs as a program if the Java Runtime Environment (JRE) is installed on the computer.
• .CLASS - compiled source code which are platform-independent. If a source file has more than one class, each class is compiled into a separate .class file. These .class files can be loaded by any Java Virtual Machine (JVM).

 Java File Extensions (.java)

Common source code file extensions include:

• .SLN - Solution File. Contains solution specific information such as links to the projects within this solution.
• .CSPROJ - C# Project File. Contains project specific information. When you add a file containing one or more classes, it is added to this file.
• .CS - C# source file.
• .Designer.CS - C# form file (a text resource file).

//Sample code snippet from the .csproj project file:

<ItemGroup>
  <Compile Include="Cyborg.cs" />
  <Compile Include="Cyborg600.cs" />
  <Compile Include="Form1.cs">
    <SubType>Form</SubType>
  </Compile>

  //...