I have recently started using Android Studio and it so quick to give you code suggestion aka code completion. It has literally reduced the amount of time I have to spend writing code by many folds. Is that possible in Emacs?
Over the past few months, I have developed an opinion that Emacs is more suited for old school guys who hacked early computers. As someone who started programming with IDEs on modern computer, one isn't really aware of lackings of IDEs, if any.
I used jEdit for a few years, but eventually I needed to program in a language for which there wasn't a good jEdit plugin available. That's when I switched to Emacs. It took me several full days to make the switch, much shorter than I expected it would, but I was far more experienced at that point than I was when I first heard of Emacs.
I wish I had switched to Emacs sooner, mostly because of Org mode, which has changed my life. Even if I were to start using an IDE because of a job requirement or whatever, I would still use Emacs for knowledge management.
FYI, I don't code in Java, and many people who do prefer IDEs, even some Emacs users.
My personal wiki consists of thousands of documents and it's powered by Emacs' Org mode. There are numerous benefits to having a knowledge base stored as plain text files that are managed using a powerful text editor, such as the ability to refer to any document in my wiki in under two seconds. I use my wiki hundreds of times per day, and the thought of using LibreOffice or Word to manage a similarly-sized knowledge base is unpleasant.