(ELisp) automatically nesting next line using brace return - emacs

Question

I'm completely new to both Lisp and Emacs. In Emacs, when coding in Java for example, I want to be able to type "{" then hit "ENTER" and have the next line be ready for whatever is nested in the braces. For example, if I have the following line:
public void method()
and I type "{" then hit return I should get this:
public void method() {
// indentation applied, no additional tabbing necessary
}
I'm already able to insert by pairs, for example, typing "{" gives "{}" with my cursor between the braces. I did this by adding these lines to the emacs init file:
;; insert by pairs (parens, quotes, brackets, braces)
(defun insert-pair (leftChar rightChar)
(if (region-active-p)
(let (
(p1 (region-beginning))
(p2 (region-end))
)
(goto-char p2)
(insert rightChar)
(goto-char p1)
(insert leftChar)
(goto-char (+ p2 2))
)
(progn
(insert leftChar rightChar)
(backward-char 1) ) )
)
(defun insert-pair-brace () (interactive) (insert-pair "{" "}") )
(global-set-key (kbd "{") 'insert-pair-brace)
To get the auto-nesting I described above, I added these lines:
;; automatically nest next line
(defun auto-nest ()
(insert "\n\n")
(backward-char 1)
(insert "\t")
)
(defun auto-nest-brace () (interactive) (auto-nest) )
(global-set-key (kbd "{ RET") 'auto-nest-brace)
When I start up Emacs, however, I get this message:
error: Key sequence { RET starts with non-prefix key {
What am I doing wrong, and what can I do to fix it? I don't want to use a different key combination to do this. There are a lot of text editors in which this auto-nesting is standard, and it should be easy enough to code up in ELisp.

Answer 1

It's great that you are trying to add this functionality to Emacs yourself, but there's no need to reinvent the wheel here. Emacs already has a command for the purpose of auto-indenting; it's called newline-and-indent. It is bound to C-j by default, but you can rebind it to RET
globally:
(global-set-key (kbd "RET") 'newline-and-indent)
for a specific mode only:
(require 'cc-mode)
(define-key java-mode-map (kbd "RET") 'newline-and-indent)
java-mode-map is defined in cc-mode.el and not available by default, that's why you have to require cc-mode before you can modify java-mode-map.
Note that newline-and-indent indents according to major mode. That is, if you're e.g. in java-mode and press RET in some random location that's not meaningful w/r/t Java syntax, it won't insert additional whitespace at the beginning of the new line.
To read all there is to know about newline-and-indent do
C-h f newline-and-indent RET

Answer 2

I have something similar in my emacs config which I have been using for a while. It calls 'newline-and-indent twice then moves the point one line up before indenting correctly. Here is the snippet of code to do this from my config file:
;; auto indent on opening brace
(require 'cc-mode)
(defun av/auto-indent-method ()
"Automatically indent a method by adding two newlines.
Puts point in the middle line as well as indent it by correct amount."
(interactive)
(newline-and-indent)
(newline-and-indent)
(forward-line -1)
(c-indent-line-or-region))
(defun av/auto-indent-method-maybe ()
"Check if point is at a closing brace then auto indent."
(interactive)
(let ((char-at-point (char-after (point))))
(if (char-equal ?} char-at-point)
(av/auto-indent-method)
(newline-and-indent))))
(define-key java-mode-map (kbd "RET") 'av/auto-indent-method-maybe)
Pretty straightforward as you can see. Hopefully it will work for you. I have not used it in any other modes except java.

Answer 3

You want a combination of auto pairs (or alternatives) plus auto indentation. Check out the emacswiki on the former: http://www.emacswiki.org/emacs/AutoPairs
And on the latter:
http://www.emacswiki.org/emacs/AutoIndentation