# Code reference information

## Parameter info

The Parameter Info popup shows the names of parameters in method and function calls. IntelliJ IDEA automatically shows a popup with all available method signatures within 1 second ( 1000 milliseconds) after you type an opening bracket in the editor, or select a method from the suggestion list.

You can explicitly invoke the popup if it has closed or if your IDE is [configured not to show the popup automatically](#configure-parameter-info-popup). To do so, press `Ctrl+P` (Windows), `⌘ P` (macOS), `⌘ P` (IntelliJ IDEA Classic (macOS)), `⌘ P` (macOS System Shortcuts), `Ctrl+P` (XWin), `Ctrl+P` (GNOME), `Ctrl+P` (KDE), `Alt+Shift+P` (Emacs), `Ctrl+P` (Sublime Text), `Ctrl+P` (Sublime Text (macOS)), `Ctrl+P` (NetBeans), `Ctrl+Shift+Space` (Visual Studio), `⌘ P` (Visual Studio (macOS)), `Ctrl+P` (Eclipse), `⌃ ⇧ Space` (Eclipse (macOS)) (or click `View | Parameter Info`).

![Parameter info popup](https://resources.jetbrains.com.cn/help/img/idea/2026.2/parameter-info.png)

Procedure: Show full method or function signatures

By default, the parameter info popup shows simple signatures. You can configure the IDE to show full signatures that include method names and returned types.

* In the Settings dialog (`Ctrl+Alt+S` (Windows), `⌘ Comma` (macOS), `⌘ Comma` (IntelliJ IDEA Classic (macOS)), `⌘ Comma` (macOS System Shortcuts), `Ctrl+Alt+S` (XWin), `Ctrl+Alt+S` (GNOME), `Ctrl+Alt+S` (KDE), `Ctrl+Alt+S` (Emacs), `Ctrl+Alt+S` (Sublime Text), `⌘ Comma` (Sublime Text (macOS)), `Ctrl+Alt+S` (NetBeans), `Ctrl+Alt+S` (Visual Studio), `⌘ Comma` (Visual Studio (macOS)), `Ctrl+Alt+S` (Eclipse), `⌘ Comma` (Eclipse (macOS))), go to `Editor | General | Code Completion | Popup`, and select the Show full method signatures checkbox.

![Full signatures enabled](https://resources.jetbrains.com.cn/help/img/idea/2026.2/full-signatures.png)

Procedure: Configure the parameter info popup

1. In the Settings dialog (`Ctrl+Alt+S` (Windows), `⌘ Comma` (macOS), `⌘ Comma` (IntelliJ IDEA Classic (macOS)), `⌘ Comma` (macOS System Shortcuts), `Ctrl+Alt+S` (XWin), `Ctrl+Alt+S` (GNOME), `Ctrl+Alt+S` (KDE), `Ctrl+Alt+S` (Emacs), `Ctrl+Alt+S` (Sublime Text), `⌘ Comma` (Sublime Text (macOS)), `Ctrl+Alt+S` (NetBeans), `Ctrl+Alt+S` (Visual Studio), `⌘ Comma` (Visual Studio (macOS)), `Ctrl+Alt+S` (Eclipse), `⌘ Comma` (Eclipse (macOS))), go to `Editor | General | Code Completion | Popup`.

2. In the Show the parameter info popup in ... milliseconds field, specify the time in milliseconds after which the popup should appear.

If you don't want the popup to appear automatically, clear the Show the parameter info popup in ... milliseconds checkbox.

## Quick Documentation

You can get quick information for any symbol right from the editor with the Quick Documentation feature. It shows you code documentation in a popup as you hover over code elements. Note that the symbol must be supplied with documentation comments created in accordance with the [Javadoc](https://www.oracle.com/technical-resources/articles/java/javadoc-tool.html)

markup or with the SDK documentation.

The feature allows you to access both downloaded documentation and external documentation for which you only specify its URL. For more information about adding code documentation, refer to:

* [Configure library documentation](library.html#add-library-docs)

* [Configure SDK documentation](configure-sdk-documentation.html)

### Quick Documentation in a popup

Procedure: View Quick Documentation in a popup

* Hover over the necessary symbol in the editor.

* Place the caret at the symbol and press `Ctrl+Q` (Windows), `F1` (macOS), `⌃ J` (IntelliJ IDEA Classic (macOS)), `⌘ I` (macOS System Shortcuts), `Ctrl+Q` (XWin), `Ctrl+Q` (GNOME), `Ctrl+Q` (KDE), `Ctrl+Q` (Emacs), `Ctrl+Q` (Sublime Text), `Ctrl+Q` (Sublime Text (macOS)), `Ctrl+Q` (NetBeans), `Ctrl+K, I` (Visual Studio), `⌘ K, I` (Visual Studio (macOS)), `Alt+Middle-Click` (Eclipse), `⌥ Middle-Click` (Eclipse (macOS)) ( `View | Quick Documentation`).

* Place the caret at the end of the symbol, type `..`, and select Quick Documentation.

To open the documentation in a dedicated tool window, press `Ctrl+Q` (Windows), `F1` (macOS), `⌃ J` (IntelliJ IDEA Classic (macOS)), `⌘ I` (macOS System Shortcuts), `Ctrl+Q` (XWin), `Ctrl+Q` (GNOME), `Ctrl+Q` (KDE), `Ctrl+Q` (Emacs), `Ctrl+Q` (Sublime Text), `Ctrl+Q` (Sublime Text (macOS)), `Ctrl+Q` (NetBeans), `Ctrl+K, I` (Visual Studio), `⌘ K, I` (Visual Studio (macOS)), `Alt+Middle-Click` (Eclipse), `⌥ Middle-Click` (Eclipse (macOS)) one more time.

[Video](https://resources.jetbrains.com.cn/help/img/idea/2026.2/quick-doc-popup.mp4)

Click ![the Show Options Menu icon](https://resources.jetbrains.com.cn/help/img/idea/2026.2/app.actions.more.svg) in the popup to change the font size, display the quick documentation toolbar, or go to the source code.

> **Tip:**
> To specify the delay after which the popup should appear,   in the Settings dialog (`Ctrl+Alt+S` (Windows), `⌘ Comma` (macOS), `⌘ Comma` (IntelliJ IDEA Classic (macOS)), `⌘ Comma` (macOS System Shortcuts), `Ctrl+Alt+S` (XWin), `Ctrl+Alt+S` (GNOME), `Ctrl+Alt+S` (KDE), `Ctrl+Alt+S` (Emacs), `Ctrl+Alt+S` (Sublime Text), `⌘ Comma` (Sublime Text (macOS)), `Ctrl+Alt+S` (NetBeans), `Ctrl+Alt+S` (Visual Studio), `⌘ Comma` (Visual Studio (macOS)), `Ctrl+Alt+S` (Eclipse), `⌘ Comma` (Eclipse (macOS))), go to `Editor | Code Editing | Editor Tooltips` and enter the necessary value in the Tooltip delay field.

When you’re viewing documentation for a library or dependency, you can access its sources right from the popup or tool window by clicking Download documentation.

![Downloading documentation from popup](https://resources.jetbrains.com.cn/help/img/idea/2026.2/ij_download_documentation_sources.png)

Procedure: Disable Quick Documentation on hover

By default, the quick documentation popup appears as you hover over code elements. You can configure the IDE to display the popup only after you explicitly invoke the Quick Documentation feature.

* Click ![the Show Options Menu icon](https://resources.jetbrains.com.cn/help/img/idea/2026.2/app.actions.more.svg) in the popup and disable the Show on Mouse Move option.

* In the Settings dialog (`Ctrl+Alt+S` (Windows), `⌘ Comma` (macOS), `⌘ Comma` (IntelliJ IDEA Classic (macOS)), `⌘ Comma` (macOS System Shortcuts), `Ctrl+Alt+S` (XWin), `Ctrl+Alt+S` (GNOME), `Ctrl+Alt+S` (KDE), `Ctrl+Alt+S` (Emacs), `Ctrl+Alt+S` (Sublime Text), `⌘ Comma` (Sublime Text (macOS)), `Ctrl+Alt+S` (NetBeans), `Ctrl+Alt+S` (Visual Studio), `⌘ Comma` (Visual Studio (macOS)), `Ctrl+Alt+S` (Eclipse), `⌘ Comma` (Eclipse (macOS))), go to `Editor | Code Editing | Quick Documentation` and clear the Show quick documentation on hover  checkbox.

In this case, to view documentation for a symbol at caret, press `Ctrl+Q` (Windows), `F1` (macOS), `⌃ J` (IntelliJ IDEA Classic (macOS)), `⌘ I` (macOS System Shortcuts), `Ctrl+Q` (XWin), `Ctrl+Q` (GNOME), `Ctrl+Q` (KDE), `Ctrl+Q` (Emacs), `Ctrl+Q` (Sublime Text), `Ctrl+Q` (Sublime Text (macOS)), `Ctrl+Q` (NetBeans), `Ctrl+K, I` (Visual Studio), `⌘ K, I` (Visual Studio (macOS)), `Alt+Middle-Click` (Eclipse), `⌥ Middle-Click` (Eclipse (macOS)) or select `View | Quick Documentation` from the main menu. The documentation will be shown in a popup, but you can configure the IDE to [display it in the tool window](#quick-doc-in-tool-window) right away.

### Quick Documentation in the tool window

Procedure: View documentation in the tool window

With the default settings, pressing `Ctrl+Q` (Windows), `F1` (macOS), `⌃ J` (IntelliJ IDEA Classic (macOS)), `⌘ I` (macOS System Shortcuts), `Ctrl+Q` (XWin), `Ctrl+Q` (GNOME), `Ctrl+Q` (KDE), `Ctrl+Q` (Emacs), `Ctrl+Q` (Sublime Text), `Ctrl+Q` (Sublime Text (macOS)), `Ctrl+Q` (NetBeans), `Ctrl+K, I` (Visual Studio), `⌘ K, I` (Visual Studio (macOS)), `Alt+Middle-Click` (Eclipse), `⌥ Middle-Click` (Eclipse (macOS)) (`View | Quick Documentation`) opens quick documentation in a popup. You can change the settings to view documentation in the tool window.

* In the quick documentation popup, click ![the Show Options Menu icon](https://resources.jetbrains.com.cn/help/img/idea/2026.2/app.actions.more.svg) and disable the Show Documentation Popup First option.

* In the Documentation tool window, click the ![Show Options Menu](https://resources.jetbrains.com.cn/help/img/idea/2026.2/app.expui.general.settings.svg) icon on the tool window toolbar and disable the Show Documentation Popup First option.

Procedure: Keep documentation in the tool window

You can open a piece of documentation for a specific code element in the tool window and keep viewing documentation for other elements in your current file.

1. Place the caret at the required code element and press `Ctrl+Q` (Windows), `F1` (macOS), `⌃ J` (IntelliJ IDEA Classic (macOS)), `⌘ I` (macOS System Shortcuts), `Ctrl+Q` (XWin), `Ctrl+Q` (GNOME), `Ctrl+Q` (KDE), `Ctrl+Q` (Emacs), `Ctrl+Q` (Sublime Text), `Ctrl+Q` (Sublime Text (macOS)), `Ctrl+Q` (NetBeans), `Ctrl+K, I` (Visual Studio), `⌘ K, I` (Visual Studio (macOS)), `Alt+Middle-Click` (Eclipse), `⌥ Middle-Click` (Eclipse (macOS)). If the popup appears, press `Ctrl+Q` (Windows), `F1` (macOS), `⌃ J` (IntelliJ IDEA Classic (macOS)), `⌘ I` (macOS System Shortcuts), `Ctrl+Q` (XWin), `Ctrl+Q` (GNOME), `Ctrl+Q` (KDE), `Ctrl+Q` (Emacs), `Ctrl+Q` (Sublime Text), `Ctrl+Q` (Sublime Text (macOS)), `Ctrl+Q` (NetBeans), `Ctrl+K, I` (Visual Studio), `⌘ K, I` (Visual Studio (macOS)), `Alt+Middle-Click` (Eclipse), `⌥ Middle-Click` (Eclipse (macOS)) again to switch to the tool window.

The asterisk symbol (`*`) on the documentation tab means that the tab is not pinned, so its content will be replaced by documentation for another code element that you select in the editor.

2. Right-click the tab with the documentation in the documentation tool window and enable the Keep This Documentation option.

After that, the current documentation tab will be pinned. You can return to the editor and view documentation for other code elements that will open either in the popup or in a new tab in the tool window.

[Video](https://resources.jetbrains.com.cn/help/img/idea/2026.2/keep-quick-documentation.mp4)

> **Tip:**
> Press `Ctrl+F` (Windows), `⌘ F` (macOS), `⌘ F` (IntelliJ IDEA Classic (macOS)), `⌘ F` (macOS System Shortcuts), `Ctrl+F` (XWin), `Ctrl+F` (GNOME), `Ctrl+F` (KDE), `Ctrl+Alt+S` (Emacs), `Ctrl+F` (Sublime Text), `⌘ F` (Sublime Text (macOS)), `Ctrl+F` (NetBeans), `Ctrl+F` (Visual Studio), `⌘ F` (Visual Studio (macOS)), `Ctrl+F` (Eclipse), `Ctrl+F` (Eclipse (macOS)) in the Documentation tool window to use the text search.

When you are viewing code documentation in the tool window, it is displayed on the unpinned tab (the tab marked with the asterisk symbol (`*`). There are several ways in which you can work with it:

View on hover:

You can view documentation by hovering over code elements.

Click the ![Options](https://resources.jetbrains.com.cn/help/img/idea/2026.2/app-client.expui.general.moreVertical.svg) icon on the tool window toolbar and enable the Show on Mouse Move and Auto-Update from Source options.

[Video](https://resources.jetbrains.com.cn/help/img/idea/2026.2/doc-toolwindow-on-hover.mp4)

View for symbols at the caret:

You can view documentation as you place the caret at symbols in the editor either by clicking them or by moving the caret.

Click the ![Options](https://resources.jetbrains.com.cn/help/img/idea/2026.2/app-client.expui.general.moreVertical.svg) icon on the toolbar, disable the Show on Mouse Move and enable the Auto-Update from Source options.

[Video](https://resources.jetbrains.com.cn/help/img/idea/2026.2/doc-toolwindow-at-caret.mp4)

View by using the shortcut:

You can view documentation by placing the caret at a symbol and pressing `Ctrl+Q` (Windows), `F1` (macOS), `⌃ J` (IntelliJ IDEA Classic (macOS)), `⌘ I` (macOS System Shortcuts), `Ctrl+Q` (XWin), `Ctrl+Q` (GNOME), `Ctrl+Q` (KDE), `Ctrl+Q` (Emacs), `Ctrl+Q` (Sublime Text), `Ctrl+Q` (Sublime Text (macOS)), `Ctrl+Q` (NetBeans), `Ctrl+K, I` (Visual Studio), `⌘ K, I` (Visual Studio (macOS)), `Alt+Middle-Click` (Eclipse), `⌥ Middle-Click` (Eclipse (macOS)) or selecting `View | Quick Documentation` from the main menu.

Click the ![Options](https://resources.jetbrains.com.cn/help/img/idea/2026.2/app-client.expui.general.moreVertical.svg) icon on the tool window toolbar, disable the Show on Mouse Move and Auto-Update from Source options.

[Video](https://resources.jetbrains.com.cn/help/img/idea/2026.2/doc-toolwindow-shortcut.mp4)

## External documentation

External documentation opens the necessary information in a web browser so that you can navigate to related symbols and keep the information for further reference at the same time.  After you configure external documentation for your project, you can also view it in the [Quick Documentation popup](#inline-quick-documentation).

For more information about configuring library and SDK external documentation paths, refer to:

* [Specify library documentation paths](library.html#library-documentation-paths)

* [Specify SDK documentation paths](configure-sdk-documentation.html#sdk-documentation-paths)

Procedure: View external documentation

* To view documentation for a symbol at the caret in a browser, press `Shift+F1` (Windows), `⇧ F1` (macOS), `⇧ F1` (IntelliJ IDEA Classic (macOS)), `⇧ F1` (macOS System Shortcuts), `Shift+F1` (XWin), `Shift+F1` (GNOME), `Shift+F1` (KDE), `Shift+F1` (Emacs), `Shift+F1` (Sublime Text), `⇧ F1` (Sublime Text (macOS)), `Shift+F1` (NetBeans), `Shift+F1` (Visual Studio), `⇧ F1` (Visual Studio (macOS)), `Shift+F2` (Eclipse), `⇧ F2` (Eclipse (macOS)) or select `View | External Documentation` from the main menu.

## Type Info

In IntelliJ IDEA, you can identify the type of an expression.

Procedure:

* Place the caret at the necessary code element and press `Ctrl+Shift+P` (Windows), `⌃ ⇧ P` (macOS), `⌃ ⇧ P` (IntelliJ IDEA Classic (macOS)), `⌃ ⇧ P` (macOS System Shortcuts), `Ctrl+Shift+P` (XWin), `Ctrl+Shift+P` (GNOME), `Ctrl+Shift+P` (KDE), `Ctrl+Shift+P` (Emacs), `Ctrl+Shift+P` (Sublime Text), `⌃ ⇧ P` (Sublime Text (macOS)), `Ctrl+Shift+P` (NetBeans), `Ctrl+Shift+P` (Visual Studio), `Ctrl+Shift+P` (Visual Studio (macOS)), `Ctrl+Shift+P` (Eclipse), `Ctrl+Shift+P` (Eclipse (macOS)). Alternatively,  select `View | Type Info` from the main menu.

If several expressions are available, select the desired one from the popup menu and press `Enter` (Windows), `⏎` (macOS), `⏎` (IntelliJ IDEA Classic (macOS)), `⏎` (macOS System Shortcuts), `Enter` (XWin), `Enter` (GNOME), `Enter` (KDE), `Enter` (Emacs), `Enter` (Sublime Text), `⏎` (Sublime Text (macOS)), `Enter` (NetBeans), `Enter` (Visual Studio), `⏎` (Visual Studio (macOS)), `Enter` (Eclipse), `⏎` (Eclipse (macOS)).

![Showing the expression type info](https://resources.jetbrains.com.cn/help/img/idea/2026.2/type-info.png)

## Expression static data

IntelliJ IDEA allows you to view statically known information about any Java expression in the editor. This information helps you understand complex code with heavy branching and elaborates expression type information.

Procedure:

* To view static information on Java expressions, place the caret at the expression and double-press `Ctrl+Shift+P` (Windows), `⌃ ⇧ P` (macOS), `⌃ ⇧ P` (IntelliJ IDEA Classic (macOS)), `⌃ ⇧ P` (macOS System Shortcuts), `Ctrl+Shift+P` (XWin), `Ctrl+Shift+P` (GNOME), `Ctrl+Shift+P` (KDE), `Ctrl+Shift+P` (Emacs), `Ctrl+Shift+P` (Sublime Text), `⌃ ⇧ P` (Sublime Text (macOS)), `Ctrl+Shift+P` (NetBeans), `Ctrl+Shift+P` (Visual Studio), `Ctrl+Shift+P` (Visual Studio (macOS)), `Ctrl+Shift+P` (Eclipse), `Ctrl+Shift+P` (Eclipse (macOS)).

[Video](https://resources.jetbrains.com.cn/help/img/idea/2026.2/expression-static-data.mp4)

In this example, the Expression static data action shows that the type of `list` is actually `ArrayList`, despite the variable is declared as `List`, and it's still empty at the given point (size = 0).

## Productivity tips

Copy tooltip text to the clipboard
: To copy tooltip text to the clipboard, hold `Alt` (Windows), `Alt` (macOS), `Alt` (IntelliJ IDEA Classic (macOS)), `Alt` (macOS System Shortcuts), `Alt` (XWin), `Alt` (GNOME), `Alt` (KDE), `Alt` (Emacs), `Alt` (Sublime Text), `Alt` (Sublime Text (macOS)), `Alt` (NetBeans), `Alt` (Visual Studio), `Alt` (Visual Studio (macOS)), `Alt` (Eclipse), `Alt` (Eclipse (macOS))
:
: (on Linux, hold `Ctrl+Alt`)
:
: and click the tooltip.

View context information
: If the current method or class declaration is not visible, you can view it in the tooltip by pressing `Alt+Q` (Windows), `⌃ ⇧ Q` (macOS), `⌃ ⇧ Q` (IntelliJ IDEA Classic (macOS)), `⌃ ⇧ Q` (macOS System Shortcuts), `Alt+Q` (XWin), `Alt+Q` (GNOME), `Alt+Q` (KDE), `Alt+Q` (Emacs), `Alt+Q` (Sublime Text), `Alt+Q` (Sublime Text (macOS)), `Alt+Q` (NetBeans), `Alt+Q` (Visual Studio), `⌃ ⇧ Q` (Visual Studio (macOS)), `Alt+Q` (Eclipse), `⌃ ⇧ Q` (Eclipse (macOS)).

## See also

### Getting Started

[Editor basics](using-code-editor.html)