How to comment a block in Eclipse?

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

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

Ctrl-</kbd> 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-</kbd> 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.

There are two possibilities:

##Every line prepended with //##

ctrl + / to comment
ctrl + </kbd> to uncomment

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

##Complete block surrounded with block comments /*##

ctrl + shift + / to comment
ctrl + shift + </kbd> 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.

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)

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 .

In addition, you can change Eclipse shortcut in Windows -> Preferences -> General -> Keys

For single line comment you can use Ctrl+/ and for multiple line comment you can use Ctrl + Shift + / after selecting the lines you want to comment in java editor.

On Mac/OS X you can use ⌘ + / to comment out single lines or selected blocks.

for java code

if you want comments single line then put double forward slash before code of single line manually or by pressing Ctrl +/ example: //System.Out.println("HELLO");

and for multi-line comments, Select code how much you want to comments and then press

Shift+CTRL+/

Now for XML code comments use Select code first and then press Shift+CTRL+/ for both single line and multi-line comments

For JAVA :

Single line comment:

               // this is a single line comment

To comment: Ctrl + Shift + C

To uncomment: Press again Ctrl + Shift + C

Multiple line comment:

         /* .........
            .........
            ......... */ 

First, select all the lines that you want to comment/uncomment then,

To comment: Ctrl + Shift + C

To uncomment: Press again Ctrl + Shift + C

I hope, this will work for you!

It depends upon the version of OS - for me it works with Command + 7

Using Eclipe Oxygen command + Shift + c on macOSx Sierra will add/remove comments out multiple lines of code

Using Eclipse Mars.1 CTRL + / on Linux in Java will comment out multiple lines of code. When trying to un-comment those multiple lines, Eclipse was commenting the comments. I found that if there is a blank line in the comments it will do this. If you have 10 lines of code, a blank line, and 10 more lines of code, CTRL + / will comment it all. You'll have to remove the line or un-comment them in blocks of 10.

Eclipse Oxygen with CDT, PyDev:

Block comments under Source menu

Add Comment Block Ctrl + 4

Add Single Comment Block Ctrl+Shift+4

Remove Comment Block Ctrl + 5

I have Mac ,I was also facing problem to comment multiple line in STS

I have tried

single line comment:

command+/

Multi line comment:

control+command+/ 

Multi line uncomment:

control+command+\ 

And it was success

For single line comment just use // and for multiline comments use /* your code here */

Select the text you want to Block-comment/Block-uncomment.

To comment, Ctrl + 6

To uncomment, Ctrl + 8