How to comment a block in Eclipse?


Does Eclipse have a hot key to comment a block? and to uncomment a block?

1/4/2010 7:45:04 PM

Accepted Answer

Ctrl-/ to toggle "//" comments and Ctrl-Shift-/ to toggle "/* */" comments. At least for Java, anyway - other tooling may have different shortcuts.

Ctrl-\ will remove a block of either comment, but won't add comments.

Note: As for Eclipse CDT 4.4.2, Ctrl-Shift-/ will not uncomment a "/* */" block comment. Use Ctrl-Shift-\ in that case.

EDIT: It's Ctrl on a PC, but on a Mac the shortcuts may all be Cmd instead. I don't have a Mac myself, so can't easily check.

4/21/2015 1:24:19 PM

There are two possibilities:

Every line prepended with //

ctrl + / to comment
ctrl + \ to uncomment

Note: on recent eclipse cdt, ctrl + / is used to toggle comments (and ctrl + \ has no more effect)

Complete block surrounded with block comments /*

ctrl + shift + / to comment
ctrl + shift + \ to remove


For Eclipse Editor

For Single Line (Toggle Effect)

Comment : Ctrl+Shift+c

Uncomment: Ctrl+Shift+c

For Multiple Lines (Toggle Effect) (Select the lines you want to comment)

comment : Ctrl+Shift+c

Uncomment: Ctrl+Shift+c

It is for all html , css , jsp , java . It gives toggle effect.


I came here looking for an answer and ended up finding it myself, thanks to the previous responses.

In my particular case, while editing PHP code on Eclipse Juno, I have found that the previous commands won't work for me. Instead of them, I should press Ctrl+ 7 (on the superior number key) to obtain the double bar comment ("//"). There's no way I can comment them with the previous mentioned key combinations.


I have Eclipse IDE for Java Developers Version: Juno Service Release 2 and it is -

Every line prepended with //

ctrl + / for both comment and uncomment .


As other answers pointed out, the following shortcuts are defined by default (I'm referring to editing java source - shortcut bindings can be found in eclipse Window>Preferences, under 'General'/'Keys', search for 'comment'):

  • to add a block comment, the shortcut (binding) is: Ctrl + Shift + /
  • to remove a block comment, the shortcut (binding) is: Ctrl + Shift + \

Unfortunately, these shortcuts did not work for me (on Eclipse Java EE IDE for Web Developers, version: Juno Service Release 2).

The reason, I think, is my keyboard layout (QWERTZ keyboard layout used in Germany - see here for further information), where '/' actually has to be written via 'Shift + 7'.

I therefore had to change the shortcut bindings for comments (just did it for editing java source) in the eclipse preferences (under 'General'/'Keys') as follows:

  • Change the binding of command 'Add Block Comment' (when 'Editing Java Source') from 'Ctrl + Shift + /' to 'Ctrl + Shift + 7'
  • Change the binding of command 'Remove Block Comment' (when 'Editing Java Source') from 'Ctrl + Shift + \' to 'Ctrl + Shift + 8'
  • Unbind the binding 'Ctrl + /' for command 'Toggle Comment' (when 'Editing Java Source'); instead of assigning a new binding, I simply unbound this shortcut, as there already was one with Ctrl+7 and one with Ctrl+Shift+C (which both work for me)

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