Editing Java in Visual Studio Code
Visual Studio Code is a source code editor first and foremost with rich editing features. In this document, we will go through a few Java-specific features, which are helpful when working with Java.
If you run into any issues when using the features below, you can contact us by clicking the Report an issue button below.
Code editing and navigation
With the Outline view, you can conveniently navigate your methods within the same class. Editing code is also easy with IntelliSense for smart code completions and signature details. You can use code snippets as well as various code actions such as generating Getters/Setters and organizing imports to further boost your productivity.
Java support in Visual Studio Code detects issues within your code automatically, and provides you with Quick Fix suggestions.
As a Java editor, it also supports CodeLens (references) and Javadoc hovers and highlights out of box.
Folding range allows you to fold or unfold code snippet to better view the source code.
Search for symbols
You can search for symbols in the current file or workspace to navigate your code more quickly.
To search for a symbol in the current file, use Quick Open (⌘P (Windows, Linux Ctrl+P)) then enter the '@' command, then enter the name of the symbol you're looking for. A list of potential matches will appear and be filtered as you type. Choose from the list of matches to navigate to its location.
To search for a symbol in the current workspace, start by pressing ⌘T (Windows, Linux Ctrl+T), then enter the name of the symbol. A list of potential matches will appear as before. If you choose a match that was found in a file that's not already open, the file will be opened before navigating to the match's location. Alternatively, you can also use Quick Open (⌘P (Windows, Linux Ctrl+P)) then enter the '#' command to search the current workspace. ⌘T (Windows, Linux Ctrl+T) is just the shortcut for the '#' commands, so everything works the same.
You can take a quick look at how a symbol was defined by using the Peek Definition feature. This feature displays a few lines of code near the definition inside a peek window, so you can take a look without navigating away from your current location.
To peek at a symbol's definition, place your cursor on the symbol anywhere it's used in your source code and then press ⌥F12 (Windows Alt+F12, Linux Ctrl+Shift+F10). Alternatively, you can choose Peek Definition from the context menu (right-click, then choose Peek Definition).
Go to Definition
You can also quickly navigate to where a symbol is defined by using the Go to Definition feature.
To go to a symbol's definition, place your cursor on the symbol anywhere it is used in your source code and then press F12. Alternatively, you can choose Go to Definition from the context menu (right-click, then choose Go to Definition). When there's only one definition of the symbol, you'll navigate directly to its location, otherwise the competing definitions are displayed in a peek window as described in the previous section and you have to choose the definition that you want to go to.
Navigating code with Spring Boot
Spring Boot Tools extension provides enhanced navigation and code completion support for Spring Boot projects.
@/shows all defined request mappings (mapped path, request method, source location)
@+shows all defined beans (bean name, bean type, source location)
@>shows all functions (prototype implementation)
@shows all Spring annotations in the code
To learn more about Spring Boot support with Visual Studio Code, read Spring Boot in Visual Studio Code.
Code completion in Visual Studio Code for Java is provided by Language Support for Java(TM) by Red Hat. The extension is powered by the same Java development tools (JDT) behind Eclipse, so you can expect the same level of support.
In addition, there's also AI-assisted IntelliSense called IntelliCode. It saves you time by putting what you're most likely to use at the top of your completion list. IntelliCode recommendations are based on thousands of open-source projects on GitHub each with over 100 stars, so it's trained on the most common usages from high quality projects. When combined with the context of your code, the completion list is tailored to promote those practices. Here's IntelliCode for Java in action.
IntelliCode works well with popular Java libraries and frameworks like Java SE and Spring. It will help you whether you are doing monolithic web apps or modern microservices.
With Smart Selection (semantic selection), you can expand or shrink the selection range based on the semantic information of the caret position in your source code.
- To expand the selection, use ⌃⇧⌘→ (Windows, Linux Shift+Alt+Right).
- To shrink the selection, use ⌃⇧⌘← (Windows, Linux Shift+Alt+Left).
Refactoring and Code Actions
Here we will show you the most used refactoring features for Java in Visual Studio Code, namely rename, move, extract methods and variables and more.
Rename allows you to rename variables, classes, methods, packages, folders, and almost any Java identifiers. When you rename an identifier, all references to that identifier are also renamed. The shortcut to invoke the Rename refactoring is F2. When you invoke the shortcut on an identifier in the editor, a small box displays within the editor itself where you can change the identifier name. When you press Enter, all references to that identifier are changed too.
The Move refactoring lets you move packages and classes between the source roots of a project, class members to other classes, and inner classes to upper hierarchy levels.
For example, you can perform the move refactoring on a static method if it is used more in another class than in its own class.
You can also move a class to another package.
And move an inner class to new a new file.
Extract methods and variables
Extract to constant, method, and local variables all come in handy with Java on Visual Studio Code.
After the extraction, you can also perform a rename in the same transaction.
Convert a local variable to a field
When selecting an expression, extract to field.
When selecting a variable declaration, convert the variable to field.
Generate getters and setters
You can bulk generate getters and setters for all new member variables. If the class has more than one field, the source action will prompt a Quick Pick for you to select the target fields to use to generate the accessor methods.
Resolve ambiguous imports
To deal with ambiguous imports, you now have a dropdown list to pick the right one. The code line with the unresolved type is also presented to you to help you decide.
With this source action, all the candidates are presented to you with a checklist. You can then decide what to override or implement.
equals() can be generated with default implementations. All the non-static member variables are listed, and you can customize the generated code using the check list.
There are two options for you to customize the generated code:
- If you use Java 7+, you can set
trueto generate shorter code that calls
- You can also set
instanceOfoperator to check the object types instead of calling
There is a new source action to generate the
toString() method. Customization is possible with a check list of all the member variables.
Convert to static imports
Convert static functions calls to static imports.
Generate delegate methods
Generate delegate methods
Generate constructor from super class
Add a constructor from super class.
Invert local variable
This refactoring lets you change the sense of a Boolean variable to the opposite one.
Assign parameter to new field
This source action assigns a parameter to a new field for unused parameter(s) in a constructor.
Other Code Actions supported
The list of Code Actions supported by VS Code keeps growing and only listed the most popular ones above. Other notable supported actions include (but not limited to):
- Convert anonymous class to lambda expression
- Convert lambda to anonymous class
- Create unresolved types
Visual Studio Code supports a wide range of popular Java code snippets to make you more productive, such as class/interface, syserr, sysout, if/else, try/catch, static main method. You can review all supported code snippets at vscode-java/snippets/java.json.
In addition, there's a Checkstyle for Java extension, which you can use with either existing
checkstyle configurations (Google's or Sun's Check) or your own customized files. When opening or saving a Java file, the extension will check the file format and provide quick fixes if possible.
The Checkstyle for Java extension also supports live linting.
And batch check.
The Problems panel will open when you click the Checkstyle status icon in the Status bar.
Set Checkstyle configuration file
To set the configuration file, right-click the
.xmlfile and select Set the Checkstyle Configuration File.
You can also trigger the command Checksjtyle: Set Checkstyle Configuration File to choose the configuration file in the File Explorer. You will also see the two built-in configurations:
- Google's Check
- Sun's Check
The extension looks for a
checkstyle.xml file in your workspace to make Checkstyle configuration easier.
Check the style and fix the violations
- When opening or saving a Java file, the extension will check the file format and provide Quick Fixes if possible. You can click the lightbulb button in the editor to show the available Quick Fixes.