Code completion

Invoke basic completion

1. Start typing a name. By default, IntelliJ IDEA displays the code completion popup automatically as you type.

   If automatic completion is disabled, press Ctrl+Space or choose Code | Code Completion | Basic from the main menu.

   

2. If necessary, press Ctrl+Space for the second time (or press Ctrl+Alt+Space).

   This shows inaccessible classes and members as well as static fields and methods.

   

3. When invoked for the third time, basic code completion expands the suggestion list to all classes throughout the project, regardless of the dependencies.

Invoke type-matching completion

1. Start typing. By default, IntelliJ IDEA displays the code completion popup automatically as you type. If automatic completion is disabled, press Ctrl+Shift+Space or choose Code | Code Completion | Type-Matching from the main menu.

   

2. If necessary, press Ctrl+Shift+Space once again. This lets you complete:

   • Collections, lists and arrays. IntelliJ IDEA searches for symbols with the same component type and suggests converting them.

   • Static method calls or constant references. IntelliJ IDEA scans for static methods and fields, and suggests the ones suitable in the current context.

   

Expand a string at caret to an existing word

1. Type the initial string and do one of the following:

   • Press Alt+/ or choose Code | Code Completion | Cyclic Expand Word to search for matching words before the caret.

   • Press Alt+Shift+/ or choose Code | Code Completion | Cyclic Expand Word (Backward) to search for matching words after the caret and in other open files.

   The first suggested value appears, and the prototype is highlighted in the source code.

   

2. Accept the suggestion, or hold the Alt key and keep pressing \ until the desired word is found.

Enable and configure postfix completion

• In the Settings dialog (Ctrl+Alt+S), open Editor | General | Postfix Completion and select the Enable postfix completion checkbox.

• Select Tab, Space, or Enter to be used for expanding postfix templates.

• Enable/disable a particular postfix template for the selected language.

Transform a statement with a postfix

• Type an expression and then type a postfix after a dot, for example, .if:

  public class Foo { void m(boolean b) { b.if } }

  fun foo(x: Boolean) { x.if }

  The initial expression gets wrapped with an if statement:

  public class Foo { void m(boolean b) { if (b) { } } }

  fun foo(x: Boolean) { if (x) { } }

Create custom postfix templates

1. Press Ctrl+Alt+S to open settings and then select Editor | General | Postfix Completion.

2. Click the Add button () on the toolbar.

3. In the popup menu that opens, choose the language that you need to create a postfix template for.

4. In the Create New Template dialog that opens, specify Key, a combination of symbols after the dot that will invoke the template.

5. Select which expression types the new template will be applicable to, and type the target expression in the following format: $EXPR$ <target_expression>, for example, $EXPR$ =!null.

6. To have IntelliJ IDEA automatically transform the topmost applicable expression when the template is invoked, select the Apply to the topmost expression checkbox.

   Otherwise, if the checkbox is cleared, IntelliJ IDEA will prompt you to choose the expression when you invoke the template.

7. Enable Use static import if possible: select this checkbox to have IntelliJ IDEA add static import statements instead of inserting MyUtils.methodName().

Complete tag names

1. Type the opening < and then start typing the tag name. IntelliJ IDEA displays the list of tag names appropriate in the current context.

   

   Use the Up and Down keys to scroll through the list.

2. Press Enter to accept a selection from the list. If your file is associated with a schema or a DTD, IntelliJ IDEA automatically inserts the mandatory attributes according to it.

Enable ML completion

1. Press Ctrl+Alt+S to open settings and select Editor | General | Code Completion.

2. Under Machine Learning Completion Ranking, enable the Sort completion suggestions based on machine learning option, and select the languages for which you want to use ML completion.

   

Enable relevance markers

1. Press Ctrl+Alt+S to open settings and select Editor | General | Code Completion.

2. Enable the following options:

   • Mark position changes in the completion popup: use the and icons to indicate whether the relevance of a suggestion is increasing or decreasing and therefore the suggestion has moved up or down the suggestion list.

   • Mark the most relevant item in the completion popup: use the icon to indicate the most suitable suggestion on the list.

   The suggestion list will look as follows with the icons marking reordered and the most relevant items.

   

Exclude a class or package from completion

1. Press Ctrl+Alt+S to open settings and then select Editor | General | Auto Import.

2. Under Exclude from import and completion, add the names of classes or packages that you want to exclude from completion. The classes you specify here will not appear in the suggestion list.

You can also select a completion suggestion when it appears in the editor: press Alt+Enter and select Exclude from there:

Open completion settings from the completion popup

You can quickly access code completion settings right from the completion popup.

• Click the icon in the completion popup and select Code Completion Settings.

  

After that, the Editor | General | Code Completion page of settings  Ctrl+Alt+S opens.

Narrow down the suggestion list

• You can narrow down the suggestion list by typing any part of a word (even characters from somewhere in the middle) or invoking code completion after a dot separator . IntelliJ IDEA will show suggestions that include the characters you have entered in any positions.

  This makes the use of wildcards unnecessary:

  

  In case of CamelCase or snake_case names, type the initial letters only. IntelliJ IDEA automatically recognizes and matches the initial letters.

Accept a suggestion

You can accept a suggestion from the list in one of the following ways:

• Press Enter or double-click a list item to insert it to the left of the caret.

• Press Tab to replace the characters to the right from the caret.

• Use Ctrl+Shift+Enter to make the current code construct syntactically correct (balance parentheses, add missing braces and semicolons, and so on).

• You can also use specific keys and custom characters to accept the selected completion suggestion. To enable these features, go to the Editor | General | Code Completion page of settings  Ctrl+Alt+S and do the following:

  1. To use specific keys, select the Insert the selected suggestion by pressing space, dot, or other context-dependent keys checkbox. These keys depend on the language, your context, and so on. For Java, such keys include Space, Tab, [ and ], ( and ), and some more.

  2. To also use custom characters, enter the characters into the Additional characters to accept the completion field.

Negate an expression

You can negate an expression in Java by pressing ! after you have selected it from the suggestion list. As a result, the expression will be negated:

Negating an expression works this way if you have the Insert selected suggestion by pressing space, dot, or other context-dependent keys option enabled in the Code Completion settings page, or invoke code completion explicitly, or change a selection in the suggestion list explicitly.

Completion shortcuts

You can use the following live templates shortcuts for one of the most frequently used statements:

• sout: prints System.out.printIn()

• soutm: adds the current class and method names

• soutp: adds method parameter names and values

• soutv: adds the last variable value

• soutc: inserts the System.out::printIn method reference where a consumer function is expected

View reference

• You can use the Quick Definition view by pressing Ctrl+Shift+I when you select an entry in the suggestion list:

  

• You can use the Quick Documentation by pressing Ctrl+Q when you select an entry in the suggestion list:

  

View code hierarchy

You can view code hierarchy when you've selected an entry from the suggestion list:

• Ctrl+H - view type hierarchy

• Ctrl+Alt+H - view call hierarchy.

• Ctrl+Shift+H - view method hierarchy.