The J# (pronounced Jay Sharp) programming language is a transitional language for programmers of Sun's Java and Microsoft's J++ languages, so they may use their existing knowledge, and applications on Microsoft's .NET platform.

As with J++, it only supports a limited set of Java's features.

Fundamental differences between J# and Java

Java and J# use the same general syntax but the API differs. One example is the FileOutputStream class. Instead of receiving an File object as a parameter in the Java API, Microsoft's .NET implementation receives a String object containing the file path.

J# does not compile Java-language source code to Java-language bytecode (.class files), does not support applet development or the ability to host applets in a web browser. Finally, J# does not support Java Native Interface (JNI), Raw Native Interface (RNI), and Remote Method Invocation (RMI).

J# Architecture