A Steve Jobs quote: "We want to bring Java back to the desktop in a really big way. I'm here today to personally tell you we are working hard to make Mac the best Java delivery vehicle on the planet. The biggest thing we are doing is we are going to bundle Java 2 SE into every single copy of Mac OS X the upcoming Macintosh operating system that we ship later on this year." Apparently, he changed his mind around OSX 1…
The unusual syntax of Objective-C was always seen as a hinderance to OpenStep/Cocoa adoption, and Java was seen as the solution to that problem.
But Java wasn't a perfect fit for AppKit development, and once developers wrapped their heads around Objective-C most of them stuck with it rather than deal with Java/Cocoa idiosyncrasies. With few developers, the Java/Cocoa bridge died.