Visual J++ was Microsoft's proprietary dialect of the Java programming language which ran on Windows under Microsoft's Java virtual machine. It was part of the Microsoft Visual Studio product lineup. It included an Integrated Development Environment and many language extensions, such as the ability to make efficient use of the Win32 APIs. The primary advantage of J++ and Java was the ability to run on a byte-code virtual machine (pioneered by languages like the UCSD P-System ) at a time when Intel was threatening to cut off x86 compatibility in favor of 64-bit instruction sets.