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

• Go to Settings / Preferences | 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:

  Java

  Kotlin

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

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

  The initial expression gets wrapped with an if statement:

  Java

  Kotlin

  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 the IDE settings and 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. Specify Key that is a combination of symbols 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().

Enable ML completion

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

2. Under Machine Learning-Assisted Completion, 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 the IDE 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 the IDE settings and 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 suggestions 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 the IDE settings Ctrl+Alt+S opens.

Narrow down the suggestions list

• You can narrow down the suggestions 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've 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 to insert the selected completion suggestion: go to the Editor | General | Code Completion page of the IDE settings Ctrl+Alt+S and select the Insert selected suggestion by pressing space, dot, or other context-dependent keys option. These keys depend on the language, your context, and so on. For Java, such keys include Space, Tab, [ and ], ( and ), and some more.

note

While this setting helps you save time, turning it on may result in items being inserted accidentally.

Negate an expression

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

Gif

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 suggestions 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 Definitions by pressing Ctrl+Shift+I when you select an entry in the suggestions list:

  

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

  

View code hierarchy

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

• Ctrl+H - view type hierarchy

• Ctrl+Alt+H - view call hierarchy.

• Ctrl+Shift+H - view method hierarchy.