IntelliJ IDEA 2021.2 Help

Migrate from Eclipse to IntelliJ IDEA

Switching from Eclipse to IntelliJ IDEA, especially if you've been using Eclipse for a long time, requires understanding some fundamental differences between the two IDEs, including their user interfaces, compilation methods, shortcuts, project configuration and other aspects.

Import an Eclipse project to IntelliJ IDEA

You can import either an Eclipse workspace or a single Eclipse project. To do this, click Open on the Welcome Screen or select File | Open in the main menu.

IntelliJ IDEA automatically detects Eclipse projects located on your computer and places them in the dedicated node right on the Welcome screen. This node will be available among the recent projects until you decide to remove it. When the Eclipse project is in the node, just click it to quickly open it in the IDE.

Opening an Eclipse project from the Welcome screen

If your project uses a build tool such as Maven or Gradle, we recommend selecting the associated build file pom.xml or build.gradle when importing the project. For more information on how to import a project, refer to Import a project from Eclipse.

If you'd like to import your existing run configurations from Eclipse, consider using this third-party plugin.

User Interface

No workspace

The first thing you'll notice when launching IntelliJ IDEA is that it has no workspace concept. This means that you can work with only one project at a time. While in Eclipse you normally have a set of projects that may depend on each other, in IntelliJ IDEA you have a single project that consists of a set of modules.

If you have several unrelated projects, you can open them in separate windows.

If you still want to have several unrelated projects opened in one window, as a workaround you can configure them as modules.

IntelliJ IDEA vs Eclipse terminology

The table below compares the terms in Eclipse and IntelliJ IDEA:

EclipseIntelliJ IDEA
WorkspaceProject
ProjectModule
FacetFacet
LibraryLibrary
JRESDK
Classpath variablePath variable

No perspectives

The second big surprise when you switch to IntelliJ IDEA is that it has no perspectives.

It means that you don't need to switch between different workspace layouts manually to perform different tasks. The IDE follows your context and brings up the relevant tools automatically.

IntelliJ IDEA project overview

Tool windows

Just like in Eclipse, in IntelliJ IDEA you also have tool windows. To open a tool window, click it in the tool window bar:

Tool windows bars

If the tool window bar is hidden, you can open any tool window by hovering over the corresponding icon in the bottom left corner:

Tool windows bars menu

If you want to make the tool window bar visible for a moment, you can press Alt twice and hold it.

If you don't want to use the mouse, you can always switch to any toolbar by pressing the shortcut assigned to it. The most important shortcuts to remember are:

  • Project: Alt+1

  • Commit: Alt+9

  • Terminal: Alt+F12

Another thing about tool windows is that you can drag, pin, unpin, attach and detach them:

Moving tool windows

To help store/restore the tool windows layout, there are two useful commands:

  • Window | Store Current Layout as Default
  • Window | Restore Default Layout (also available via Shift+F12)

Multiple windows

Windows management in IntelliJ IDEA is slightly different from Eclipse. You can't open several windows with one project, but you can detach any number of editor tabs into separate windows.

Always select opened files

By default, IntelliJ IDEA doesn't change the selection in the Project tool window when you switch between editor tabs. However, you can enable it in the tool window settings:

Enabling the 'Always select opened file' option

General workflows

No 'save' button

IntelliJ IDEA has no Save button. Since in IntelliJ IDEA you can undo refactorings and revert changes from Local History, it makes no sense to ask you to save your changes every time.

Still, it's worth knowing that physical saving to disk is triggered by certain events, including compilation, closing a file, switching focus out of the IDE, and so on. You can change this behavior via Settings/ Preferences | Appearance & Behavior | System Settings:

Configuring the system settings

Save actions

If you are an experienced Eclipse user, you are familiar with save actions: the actions triggered automatically on save, such as reformatting code, organizing imports, and so on.

IntelliJ IDEA also features save actions that you can find and enable in Settings/ Preferences | Tools | Actions on Save.

Settings/Preferences: Actions on save

On top of that, IntelliJ IDEA offers you to run the corresponding actions automatically on commit:

Committing changes to VCS

Or manually:

  • Code | Reformat Code Ctrl+Alt+L

  • Code | Optimize Imports Ctrl+Alt+O

  • Code | Code Cleanup

Compilation

The way IntelliJ IDEA compiles projects is different from Eclipse in a number of ways.

Auto-compilation

By default, IntelliJ IDEA doesn't automatically compile projects on saving because normally we don't invoke the save action explicitly in IntelliJ IDEA.

If you want to mimic the Eclipse behavior, you can invoke the Build Project action Ctrl+F9- it will save the changed files and compile them.

You can also enable the Build project save action in Settings/ Preferences | Tools | Actions on Save.

Note that automatic compilation in IntelliJ IDEA differs from that in Eclipse. In Eclipse it's not fully automatic, as it is triggered by the save action invoked by the user explicitly, whereas in IntelliJ IDEA it is invoked implicitly when you type in the editor.

This is why, even if the Build project option is enabled, IntelliJ IDEA doesn't perform automatic compilation if at least one application is running: it will reload classes in the application implicitly. In this case you can call Build | Build Project Ctrl+F9.

Problems tool window

The Problems tool window appears if the Build project option is enabled in save actions. It shows a list of problems that were detected on project compilation.

Problems tool window

Eclipse compiler

While Eclipse uses its own compiler, IntelliJ IDEA uses the javac compiler bundled with the project JDK. If you must use the Eclipse compiler, navigate to Settings | Preferences | Build, Execution, Deployment | Compiler | Java Compiler and select it as shown below:

Configuring the Eclipse compiler

The biggest difference between the Eclipse and javac compilers is that the Eclipse compiler is more tolerant to errors, and sometimes lets you run code that doesn't compile.

In situations when you need to run code with compilation errors in IntelliJ IDEA, replace the Build option in your run configuration with Build, no error check:

Running code with compilation errors

Shortcuts

IntelliJ IDEA shortcuts are completely different from those in Eclipse.

The table below shows how the top Eclipse actions (and their shortcuts) are mapped to IntelliJ IDEA (you may want to print it out to always have it handy).

EclipseIntelliJ IDEA
ActionShortcutActionShortcut
Code completionCtrl+SpaceBasic completionCtrl+Space
--Type-matching completionCtrl+Shift+Space
--Statement completionCtrl+Shift+Enter
Quick accessCtrl+3Search everywhereDouble Shift
Maximize active view or editorCtrl+MHide all tool windowsCtrl+Shift+F12
Open typeCtrl+Shift+TNavigate to classCtrl+N
Open resourceCtrl+Shift+RNavigate to fileCtrl+Shift+N
--Navigate to symbolCtrl+Alt+Shift+N
Next viewCtrl+F7--
--Recent filesCtrl+E
Quick outlineCtrl+OFile structureCtrl+F12
Move linesAlt+Up/DownMove linesAlt+Shift+Up/ Alt+Shift+Down
Delete linesCtrl+DDelete linesCtrl+Y
Quick fixCtrl+1Show intention actionAlt+Enter
Quick switch editorCtrl+ESwitcherCtrl+Shift+Tab
--Recent filesCtrl+E
Quick hierarchyCtrl+TNavigate to type hierarchyCtrl+H
--Navigate to method hierarchyCtrl+Shift+H
--Show UML popupCtrl+Alt+U
Last edit locationCtrl+QLast edit locationCtrl+Shift+Backspace
Next editorCtrl+F6Select next tabAlt+Right
RunCtrl+Shift+F11RunShift+F10
DebugCtrl+F11DebugShift+F9
Correct indentationCtrl+IAuto-indent linesCtrl+Alt+I
FormatCtrl+Shift+FReformat codeCtrl+Alt+L
Surround withCtrl+Alt+ZSurround withCtrl+Alt+T
--Surround with live templateCtrl+Alt+J
Open declarationF3Navigate to declarationCtrl+B
--Quick definitionCtrl+Shift+I
Open type hierarchyF4Navigate to type hierarchyCtrl+H
--Show UML popupCtrl+Alt+U
References in workspaceCtrl+Shift+GFind usagesAlt+F7
--Show usagesCtrl+Alt+F7
--Find usages settingsCtrl+Alt+Shift+F7
Open search dialogCtrl+HFind in FilesCtrl+Shift+F
Occurrences in fileAlt+Ctrl+UHighlight usages in fileCtrl+Shift+F7
Copy linesCtrl+Alt+DownDuplicate linesCtrl+D
Extract local variableCtrl+Alt+LExtract variableCtrl+Alt+V
Assign to fieldCtrl+2/ Ctrl+FExtract fieldCtrl+Alt+F
Show refactor quick menuCtrl+Alt+TRefactor thisCtrl+Alt+Shift+T
RenameCtrl+Alt+RRenameShift+F6
Go to lineCtrl+LNavigate to lineCtrl+G
Structured selectionAlt+Shift+Up/ Alt+Shift+DownSelect word at caretCtrl+W/ Ctrl+Shift+W
Find nextCtrl+JFind nextF3
Show inCtrl+Alt+WSelect inAlt+F1
BackCtrl+[BackCtrl+Alt+Left
ForwardCtrl+]ForwardCtrl+Alt+Right

Eclipse keymap

For Eclipse users who prefer not to learn new shortcuts, IntelliJ IDEA provides the Eclipse keymap which closely mimics its shortcuts:

Eclipse keymap

Find action

When you don't know the shortcut for some action, try using the Find action feature available via Ctrl+Shift+A. Start typing to find an action by its name, see its shortcut, or call it:

The Find Action dialog

Coding assistance

Both Eclipse and IntelliJ IDEA provide coding assistance features, such as code completion, code generation, quick-fixes, live templates, and so on.

Quick-fixes

To apply a quick-fix in IntelliJ IDEA, press Alt+Enter:

Applying quick-fixes

All quick-fixes are based on inspections configured in Settings/ Preferences | Editor | Inspections:

the Inspections dialog

If you want to apply a quick-fix to several places at once (that is to a whole folder, module or even a project), you can do it by running the corresponding inspection via Code | Analyze Code | Run Inspection By Name... or by running the whole batch of inspections via Code | Inspect Code:

Analysing code in IntelliJ IDEA

Apart from outright problems, IntelliJ IDEA also recognizes code constructs that can be improved or optimized via the so-called intentions (also available with Alt+Enter):

Applying intention actions
EclipseIntelliJ IDEA
ActionShortcutActionShortcut
Quick fixCtrl+1Show intention actionAlt+Enter

Generating code

The key action for generating code is Code | Generate, available via Alt+Insert:

Generating code

This action is context-sensitive and is available not only within the editor, but also in the Project tool window and the Navigation bar:

Creating a new object in the Project tool window

Code completion

IntelliJ IDEA provides several different types of code completion, which include:

  • Basic completion

  • Second basic completion

  • Type-matching completion

  • Second type-matching completion

  • Statement completion

To learn more about the differences between these completion types, refer to the Code Completion blog post.

By default, IntelliJ IDEA doesn't show the Documentation popup for the selected item, but you can enable it in Settings/ Preferences | Editor | Code Completion | Show the documentation popup in:

Code completion

If you don't want to enable this option, you can manually invoke this popup by pressing Ctrl+Q when you need it:

Showing the quick documentation popup

When the caret is within the brackets of a method or a constructor, you can get the info about the parameters by calling Parameter Info with Ctrl+P:

Showing parameter info
EclipseIntelliJ IDEA
ActionShortcutActionShortcut
Code completionCtrl+SpaceBasic completionCtrl+Space
--Type-matching completionCtrl+Shift+Space
--Statement completionCtrl+Shift+Enter

Templates

You may be used to typing main in the editor and then calling code completion to have it transformed into a main method definition. However, IntelliJ IDEA templates are a little different:

TemplateEclipseIntelliJ IDEA
Define a main methodmainpsvm
Iterate over an arrayforitar
Iterate over a collectionforitco
Iterate over a listforitli
Iterate over an iterable using foreach syntaxforeachiter
Print to System.outsysoutsout
Print to System.errsyserrserr
Define a static fieldstatic_finalpsf

The list of available templates can be found in Settings/Preferences | Editor | Live Templates. There you can also add your own templates or modify any existing ones.

While IntelliJ IDEA suggests templates in code completion results, you can quickly expand any template without using code completion by pressing Tab.

Postfix templates

In addition to 'regular' templates, IntelliJ IDEA offers the so-called postfix templates. They are useful when you want to apply a template to an expression you've already typed. For instance, type a variable name, add .ifn and press Tab. IntelliJ IDEA will turn your expression into a if (...==null){...} statement.

To see a complete list of available postfix templates, go to Settings/Preferences | Editor | General | Postfix Completion.

Surround with live template

The surround with templates is another addition that works similarly to live templates but can be applied to the selected code with Ctrl+Alt+J.

To define your own surround with template, go to Settings/Preferences | Editor | Live Templates and use $SELECTION$ within the template text:

$LOCK$.readLock().lock(); try { $SELECTION$ } finally { $LOCK$.readLock().unlock(); }

Navigation

The table below roughly maps the navigation actions available in Eclipse with those in IntelliJ IDEA:

EclipseIntelliJ IDEA
ActionShortcutActionShortcut
Quick accessCtrl+3Search everywhereDouble Shift
Open typeCtrl+Shift+TNavigate to classCtrl+N
Open resourceCtrl+Shift+RNavigate to fileCtrl+Shift+N
--Navigate to symbolCtrl+Alt+Shift+N
Quick switch editorCtrl+ESwitcherCtrl+Tab
--Recent filesCtrl+E
Open declarationF3Navigate to declarationCtrl+B
Open type hierarchyF4Navigate to type hierarchyCtrl+H
--Show UML popupCtrl+Alt+U
Quick outlineCtrl+OFile structureCtrl+F12
BackCtrl+[BackCtrl+Alt+Left
ForwardCtrl+]ForwardCtrl+Alt+Right

Later, when you get used to these navigation options and need more, refer to Top 20 Navigation Features in IntelliJ IDEA.

Refactorings

The following table maps the shortcuts for the most common refactorings in Eclipse with those in IntelliJ IDEA:

EclipseIntelliJ IDEA
ActionShortcutActionShortcut
Extract local variableCtrl+Alt+LExtract variableCtrl+Alt+V
Assign to fieldCtrl+2Extract fieldCtrl+Alt+F
Show refactor quick menuAlt+Shift+TRefactor thisCtrl+Alt+Shift+T
RenameCtrl+Alt+RRenameShift+F6

To learn more about many additional refactorings that IntelliJ IDEA offers, refer to Top 20 Refactoring Features in IntelliJ IDEA

Undo

Sometimes, refactorings may affect a lot of files in a project. IntelliJ IDEA not only takes care of applying changes safely, but also lets you revert them. To undo the last refactoring, switch the focus to the Project tool window and press Ctrl+Z.

Search

Below is a map of the most common search actions and shortcuts:

EclipseIntelliJ IDEA
ActionShortcutActionShortcut
Open search dialogCtrl+HFind in FilesCtrl+Shift+F
References in workspaceCtrl+Shift+GFind usagesAlt+F7
--Show usagesCtrl+Alt+F7
--Find usages settingsCtrl+Alt+Shift+F7
Occurrences in fileAlt+Ctrl+UHighlight usages in fileCtrl+F7

Code formatting

IntelliJ IDEA code formatting rules (available via Settings/Preferences | Editor | Code Style) are similar to those in Eclipse, with some minor differences. You may want to take note of the fact that the Use tab character option is disabled by default, the Indent size may be different, etc.

Code formatting

If you would like to import your Eclipse formatter settings, go to Settings/Preferences | Editor | Code Style | Java, click the Show Scheme Actions button, click Import Scheme and select the exported Eclipse formatter settings (an XML file).

Note that there may be some discrepancies between the code style settings in IntelliJ IDEA and Eclipse. For example, you cannot tell IntelliJ IDEA to put space after (but not before). If you want IntelliJ IDEA to use the Eclipse formatter, consider installing the Eclipse code formatter plugin.

EclipseIntelliJ IDEA
ActionShortcutActionShortcut
FormatCtrl+Shift+FReformat codeCtrl+Alt+L

Run and reload changes

Similarly to Eclipse, IntelliJ IDEA also has Run/debug configurations dialog that you can access either from the main toolbar, or the main menu. Compare the related shortcuts:

EclipseIntelliJ IDEA
ActionShortcutActionShortcut
RunCtrl+Shift+F11RunShift+F10
DebugCtrl+F11DebugShift+F9
--MakeCtrl+F9
--Update applicationCtrl+F10

As mentioned before, by default IntelliJ IDEA doesn't compile changed files automatically (unless you configure it to do so). That means the IDE doesn't reload changes automatically. To reload changed classes, call the Build action explicitly via Ctrl+F9. If your application is running on a server, in addition to reloading you can use the Update application action via Ctrl+F10:

Debug

The debuggers in Eclipse and IntelliJ IDEA are similar but use different shortcuts:

EclipseIntelliJ IDEA
ActionShortcutActionShortcut
Step intoF5Step intoF7
--Smart step intoShift+F7
Step overF6Step overF8
Step outF7Step outShift+F8
ResumeF8ResumeF9
Toggle breakpointCtrl+Shift+BToggle breakpointCtrl+F8
Evaluate expressionCtrl+Shift+IEvaluate expressionAlt+F8

Application servers (Tomcat/TomEE, Glassfish, WebLogic, WebSphere)

Deploying to application servers in IntelliJ IDEA is more or less similar to what you are probably used to in Eclipse. To deploy your application to a server:

  1. Configure your artifacts via Project Structure | Artifacts (done automatically for Maven and Gradle projects).

  2. Configure an application server via Settings/Preferences | Application Servers.

  3. Create a run configuration, and then specify the artifacts to deploy and the server to deploy to.

You can always tell the IDE to build/rebuild your artifacts once the have been configured via Build | Build Artifacts.

Build tools (Maven/Gradle)

IntelliJ IDEA doesn't provide visual forms for editing Maven/Gradle configuration files. Once you've imported/created your Maven/Gradle project, you are free to edit its pom.xml/build.gradle files directly in the editor. Later, you can tell IntelliJ IDEA to synchronize the project model with the changed files on demand, or automatically import changes to the new build files. Any changes to the underlying build configuration will eventually need to be synced with the project model in IntelliJ IDEA.

For operations specific to Maven/Gradle, IntelliJ IDEA provides the Maven Project tool window and the Gradle tool window. Apart from your project structure, these tool windows provide a list of goals/tasks plus a toolbar with the relevant actions.

Working with Maven

For manual synchronization, use the corresponding action on the Maven/Gradle tool window toolbar: Icons actions refresh.

Run goals/tasks

Use the Maven/Gradle tool window to run any project goal/task. When you do, IntelliJ IDEA creates the corresponding run configuration which you can reuse later to run the goal/task quickly.

It's worth mentioning that any goal/task can be attached to be run before a Run Configuration. This may be useful when your goal/task generates specific files needed by the application.

Running Maven goals

Both the Maven and Gradle tool windows provide the Run Task action. It runs a Maven/Gradle command similarly to how you'd run it using the console.

Configure artifacts

If you have WAR artifacts configured in your pom.xml/build.gradle file, IntelliJ IDEA automatically configures the corresponding artifacts in Project Structure | Artifacts.

Note that when you compile your project or build an artifact, IntelliJ IDEA uses its own build process which may be faster, but is not guaranteed to be 100% accurate. If you notice inconsistent results when compiling your project with Build in IntelliJ IDEA, try using a Maven goal or a Gradle task instead.

VCS (Git, Mercurial, Subversion, Perforce)

Configure VCS roots

When you open a project located under a VCS root, IntelliJ IDEA automatically detects it and suggests adding this root to the project settings. To change version control-related project settings (or manually add a VCS root), go to Settings/Preferences | Version Control:

Working with VCS

IntelliJ IDEA works perfectly with multi-repository projects. Just map your project directories to VCS, and the IDE will take care of the rest. For Git and Mercurial, the IDE will even offer you synchronized branch control, so that you can perform branch operations on multiple repositories simultaneously (for more details, see Manage Git branches).

Edit VCS settings

Every VCS may require specific settings, for example, Path to Git executable, GitHub/Perforce credentials, and so on:

Editing VCS settings

Once you've configured the VCS settings, you'll see the Version Control tool window Alt+9.

Checking projects out

To check out a project from a VCS, click Get from Version Control on the Welcome Screen, or in the main VCS menu.

Working with local changes

The Local Changes view shows your local changes: both staged and unstaged. To simplify managing changes, all changes are organized into changelists. Any changes made to source files are automatically included into the active changelist. You can create new changelists, delete the existing ones (except for the Default changelist), and move files between changelists.

Committing new changes to VCS

Right-click the unversioned file or folder you want to ignore in the Local Changes tab of the Version Control tool window Alt+9 or in Project tool window and select Git | Add to .gitignore or Git | Add to .git/info/exclude.

If you want ignored files to be also displayed in the Local Changes view, click the View Options button on the toolbar and select Show Ignored Files.

Showing ignored files

Working with history

The Log tab of the Git tool window lets you see and search through the history of commits. You can sort and filter commits by the repository, branch, user, date, folder, or even a phrase in the description. You can find a particular commit, or just browse through the history and the branch tree:

The Log tab of the Git tool window

Working with branches

IntelliJ IDEA lets you create, switch, merge, compare and delete branches. For these operations, either use Branches from the main or context VCS menu, or the VCS operations popup (you can invoke it by pressing Alt+`, or the widget on the right of the status bar:

Working with branches

All VCS operations are available from the VCS main menu:

ActionShortcut
Version Control tool windowAlt+9
VCS operations popupAlt+`
Commit changesCtrl+K
Update projectCtrl+T
Push commitsCtrl+Shift+K
Last modified: 23 September 2021