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I just switched from Eclipse to IntelliJ. IntelliJ lacks one feature from Eclipse - when you put your mouse over a method, Eclipse shows javadoc info. I think the way to show it is to use a shortcut - command+J, but when I click it, I get something wrong as on the screen shot below. Please advise me on how I can quickly get javadoc information. I need to at least know what type a method returns.

enter image description here

kc2001
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Eugene
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11 Answers11

720

Use View | Quick Documentation or the corresponding keyboard shortcut
(by default: Ctrl+Q on Windows/Linux
and F1 on macOS in the recent IDE versions, before was Ctrl+J).
Better ee the documentation for more information.

It's also possible to enable automatic JavaDoc popup on explicit (invoked by a shortcut) code completion in Settings | Editor | General | Code completion (Autopopup documentation):

autopopup documentation

Yet another way to see the quick doc is on mouse move:

on mouse move

Paul Verest
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CrazyCoder
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    +1, could not find `Preferences` in IntelliJ Idea CE for Android. – Gaurav Agarwal Sep 06 '12 at 03:56
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    Win7 = Position cursor before class -> CTRL+q – Edward J Beckett Dec 12 '12 at 20:33
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    I was dumb enough to follow the above advice on Mac. Cmd+q. Boom! Quit IntelliJ. Genius.. – Siddhartha Sep 06 '13 at 01:51
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    It is CTRL+J on Mac. – methical Jan 03 '14 at 12:41
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    When I do this for String.compareToIgnoreCase(), I only see the signature, not the explanation of the result. Do I need to change a setting to pull in the full JavaDoc? – David W Jan 22 '14 at 15:20
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    In fact, replace ``Preferences`` by ``File | Settings`` (v 13.1) – Guillaume Husta May 13 '14 at 12:45
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    @GuillaumeHusta it depends on the OS, `Preferences` on Mac, `Settings` on Windows/Linux. – CrazyCoder May 13 '14 at 12:46
  • @CrazyCoder OK ! Thanks for the precision. That's strange to have different labels depending on the OS ?!? But that's true on the official online help page : http://www.jetbrains.com/idea/webhelp/settings-preferences-dialog.html ! – Guillaume Husta May 13 '14 at 13:17
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    Ctrl+q works on GNU/Linux too – Amr Mostafa Jul 31 '14 at 11:37
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    In 14.0.2 it is File | Settings | Editor | General | Code Completion – James Wierzba Mar 13 '15 at 16:20
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    The "Autopopup" (on mouseover) opens a completely new window (which steals focus), not a transient overlay that disappears when user moves the mouse or clicks outside the window. This is more disruptive than useful--so one of those last few things that I miss about Eclipse. I'm glad to learn about Ctrl-Q (which also closes the window), though. Very useful! – Lambart Jul 11 '15 at 06:49
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    and I was thinking that intelliJ is better than Eclipse on every aspects. – Thariq Nugrohotomo Jun 23 '16 at 06:30
  • Have you tried NetBeans? Eclipse is the worst. But IntelliJ suck pretty badly too. NetBeans is the one that annoy me the least. Also, I don't understand why this answer is approved. The question was how to make the popup happen on mouse over. – Martin Andersson Jul 09 '16 at 14:41
  • The suggestion that "It's also possible to enable automatic JavaDoc popup on code completion in Preferences | Editor | General | Code completion (Autopopup documentation)" doesn't work. That is "For explicitly invoked completion", not random hover. The *real* fix is in the answer below: "Go to File/Settings, Editor, click on General. Scroll down, then ✔ Show quick documentation on mouse move." – Jake Toronto Feb 06 '17 at 18:33
  • Its unfortunate that IDEA doesn't enable it by default. Your Preferences menu might look different depending up on your edition - Community or Professional. Search bar in preferences will help. – realPK Mar 06 '17 at 00:59
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    Shortcut for macOS with IntelliJ 2017 EAP is now `F1` for *Quick Documentation* and `Shift+F1` for *External Documentation* (web browser). – Basil Bourque Mar 13 '17 at 01:58
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    Not sure how people use ```ctrl + j``` in real life. These keys are just too far on keyboard. – RandomQuestion Apr 17 '17 at 20:12
  • Can anyone explain the use of "Autopopup documentation..." in Code Completion? – Andrew Kirna Oct 12 '17 at 20:27
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    @AndrewKirna when you invoke code completion using the keyboard shortcut (vs automatic), IDE will show you the popup documentation for the method/class you are trying to complete. – CrazyCoder Oct 13 '17 at 13:09
  • If you have a class open with Javadocs, `fn + F2` will pop up the said view window. Verified on a Mac and IDEA 2017.3. – Abhijit Sarkar Dec 27 '17 at 20:43
  • Answer updated with latest shortcuts from https://www.jetbrains.com/help/idea/viewing-reference-information.html#inline-quick-documentation, better check docs. – Paul Verest May 19 '23 at 14:42
144

Alternatively you can position your cursor on the item and show JavaDoc using

CTRL+Q

which is the default shortcut.

Edit: As Methical mentioned on Mac the shortcut is

CTRL+j (^+j not ⌘+j)

Jeff
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Dropout
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142

Go to File/Settings, Editor, click on General.

Scroll down, then ✔ Show quick documentation on mouse move.

enter image description here

Martin Wickman
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    OK with this tip we have the exact *same behavior* as with *Eclipse* (on mouse over) – Guillaume Husta May 13 '14 at 12:51
  • Feature added since v13.0. See http://www.jetbrains.com/idea/webhelp/editor.html – Guillaume Husta May 13 '14 at 13:24
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    On a mac, replace File/Settings with IntelliJ/Preferences – darKoram May 22 '14 at 15:44
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    But the feature is terrible as of 14.0. Sometimes they interfere with your ability to click on things, or get stuck and will never disappear. – CorayThan Dec 04 '14 at 01:19
  • You don’t have to expand the “Editor” menu group. You will not find this setting in one of the its entries. You have to select the *Editor* “group” **itself** and it will show a settings page on the right where the option is. – Matthias Ronge Feb 16 '15 at 08:30
24

There is nice feature which shows quick documentation when your mouse is over element.

IntelliJ 14

Editor / General -> Show quick documentation on mouse move

Older versions

Add the following line to idea.properties file:

auto.show.quick.doc=true
Michal Zmuda
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10

Configuration for IntelliJ IDEA CE 2016.3.4 to enable JavaDocs on mouse hover. I am running IntelliJ IDEA on Mac OS but believe that Linux/Windows should have similar options.

Autopopup docs: IntelliJ IDEA > Preferences > Editor > General > Code Completion

enter image description here

Documentation on mouse move: IntelliJ IDEA > Preferences > Editor > General

enter image description here

NOTE: Please hit Apply button to apply these settings

Community
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realPK
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6

For me, it wasn't just getting the javadoc window to open, but also getting the complete javadoc to present. You may still get a sparse javadoc that is based solely on the method signature if you are importing libraries from a Maven repository and do not tell Idea to include the javadocs in the download. Be sure to tick the "JavaDocs" option in the "Download Library From Maven Repository" dialog, which can be found under Project Structure -> Projtect Settings -> Libraries.

Craig Lowery
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To best mirror Eclipses functionality, enable the following settings:

  • IDE Settings/Editor -> Other.Show quick doc on mouse move
  • IDE Settings/Editor/Code Completion -> Autopopup Documentation

To see the javadoc in the autocomplete menu, hit '.' to get the popup, then hover over the object you are working with, once you get the javadoc popup, you can select an item in the popup to switch the javadoc over. Not ideal... But its something.

As another note. The search functionality of the options menu is very useful. Just type in 'doc' and you will see all the options for doc.

Also, searching for "autopopup doc" will not only find each of the options, but it will also highlight them in the menu. Pretty awesome!

Edit: Going beyond the initial question, this might be useful for people who just want quick and easy access to the docs.

After using this for a few more days, it seems just getting used to using the hotkey is the most efficient way. It will pop up the documentation for anything at the spot of where your text input marker is so you never have to touch the mouse. This works in the intellisense popup as well and will stay up while navigating up and down.

Personally, Ctrl+Q on windows was not ideal so I remapped it to Alt+D. Remaping can be done under IDE Settings/Keymap. Once in the keymap menu, just search for Quick Documentation.

J.D.
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4

Go to Settings -> Editor -> General then enable Show quick documentation on mouse move

Vork
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4

IntelliJ IDEA 15 added this feature

Now it is available as EAP.

As you can see in the picture below, the caret position doesn't influence the cursor position: enter image description here

This feature was implemented in IntelliJ IDEA 15 142.4675.3 Release Notes.

ROMANIA_engineer
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2

The closest to Eclipse will be Ctrl+Button2 Click (Scroll click)

It's called Quick Doc in IntelliJ, I wish guys from JetBrains one day add quick doc like Eclipse with Ctrl+Mouse Move it's so much better.

In my case only with only mouse move is a bit annoying, so if you search in Preferences/Settings --> Keymap for "quick documentation" you will find:

  • Win-Linux: "Ctrl+Q" and "Ctrl+Button2 Click" (Scroll click)
  • Mac: "Ctrl+J" and "Ctrl+Button2 Click" (Scroll click)
r1ckr
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1

I have noticed that selecting the method name and pressing F2(Quick Documentation) dispalys it's JavaDoc. I am using Intellij 2016, and Eclipse Keymap

razvang
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