Apache NetBeans Language Server Extension for VS Code

This is a technology preview of Apache NetBeans based extension for VS Code. Use it to get all the goodies of NetBeans via the VS Code user interface! Runs on JDK8[*] and all newer versions.

Apache NetBeans Language Server brings full featured Java development (edit-compile-debug & test cycle) for Maven and Gradle projects to VSCode. As well as other features.

Getting Started

1. Set JDK in VSCode | Preferences | Settings ... Netbeans: Jdkhome setting to point to JDK which Language Server will run on and projects will be compiled with. More below in section Selecting the JDK

2. Use Java: New Project... " command to start creating new project, or

3. Open the folder with existing pom.xml for Maven or Gradle project files (build.gradle, gradle.properties).

   • Language Server opens the project, performs priming build and might ask for Resolving problems, usually related to opening subprojects etc.

4. Or simply create a new Java class file with public static void main(String[] args) method in opened folder and start coding, compiling, debugging. Works on JDK 8 and newer.

Supported Actions

• Java: New Project... allows creation of new Maven or Gradle project
• Java: New from Template... add various files to currently selected open project. Files are:
  • Java - broad selection of various predefined Java classes
  • Unit tests - JUnit and TestNB templates for test suites and test cases
  • HTML5/JavaScript - Templates for JS, HTML, CSS,... files
  • Other - various templates for JSON, YAML, properties, ... files
• Java: Compile Workspace - invoke Maven or Gradle build
• Debugger Java 8+... - start main class or test on JDK8+. More in Debugger section
• Progress shown for long running operations with cancel support for selected types
• Native Image Debugger is a new Run configuration added which allows Java style debugging of Ahead of Time compiled native-images, produced by GraalVM. It is experimental feature which works with GDB on Linux. GDB 7.11 or GDB 10.1+ is required due to known issue #26139 in GDB 8 and 9.
  • It is also possible to attach to running native image process using Attach to Native Image launch configuation.
• Micronaut and Spring support especially for YAML configuration files with code completion and source code navigation to Java.
• Test Explorer for Java tests results visualization and execution including editor code Lenses.
• Maven and Gradle support including multi-project projects, subprojects opening and Gradle priming builds.

Project Explorer

Project Explorer provides an overview of logical project structure, groups sources together and greatly simplifies Java package structure exploration. Project Explorer is an addition to the classical workspace explorer. Use it to build, test, execute and operate your Maven and Gradle Java projects.

Debugger and Launch Configurations

Language Server Java 8+ ... launch configuration supports debugging and running Java applications using JDK8 or newer.

1. The launch configuration (debugger) is invoked when Run main | Debug main code lense is selected in the code.
2. Or Java 8+... is selected in Run and Debug activity panel.

Launch Configurations

• Launch Java 8+ App - Debug or Run current Java project
• Launch Java: Continuous Mode - Runs Micronaut project and reloads it when source code has been changed.
• Attach to Port & Attach to Process - Attach debugger actions. Available when Java 8+ ... at the bottom of drop down list is selected.
  • Select this configuration, then click the
  • Select either from available process or enter the port to connect to JVM running with JDWP.
  • Attach to Shared Memory is available on Windows in addtion to above mentioned Attach...

Default launch configurations provided by Language Server can modified in launch.json file using intellisense for available options.

Run Configurations panel

Program arguments, VM options, evironment variables,... can be set in Run Configuration panel a part of Explorer. The panel is sufficient for all typical use-cases Java programmer faces. Only advanced, expert scenarios may require touching of launch.json (which still takes precedence).

Supported Refactorings

Class level refactorings as well as variable refactorings are supported in VSCode via Apache NetBeans extension. See following screenshots:

Source Action ... context menu

Introduce refactorings available via Show Code actions light bulb

More Refactorings available also using Refactor... context menu

Surroung with refactorings

Some refactorings are two steps with like Override method ... where method to be overriden is selected in 2nd step:

Change Method Parameters refactoring

Change method parameters refactoring is provided using dedidacated form allowing to change, add, move, remove method parameters.

Move Members Refactoring

Move members refactoring provides dedicated form as well.

Some of supported refactorings:

• Convert to static import
• Rename
• Pull member up & down
• Move class
• Extract interface/method
• Extract local variable
• Assign to variable
• Generate hashCode/equals
• Generate toString()
• Surround With refactoring
• For cycle refactoring
• try-catch refactoring
• switch() statement
• while() cycle
• Inline redundant variable
• Constructor and method argument refactoring

Organize Imports

Out of the box support for organizing imports in Java sources is available. It removes unused imports, groups imports by packages and updates your imports whenever a file is saved. In addition to the defaults, there is a rich set of configuration options.

Go to VSCode Preferences | Settings and search for NetBeans to set Netbeans > Java > Imports: options:

• Count For Using Star Import - Class count to use a star-import, 999 means any number
• Count For Using Static Star Import - Members count to use a static star-import, 999 means any number
• Groups - Groups of import statements (specified by their package prefixes) and their sorting order. Import statements within a group are ordered alphabetically

And Netbeans > Java > On Save: Organize Imports - Enable organize imports action on a document save

JavaDoc smart editing

When adding JavaDoc to code NetBeans assists by suggesting to insert preformatted and prepopulated JavaDoc comment. Type /** above method signature and IDE offers to complete the JavaDoc. The action creates JavaDoc comment with all arguments prepared.

Source Code formatting

Formatting source code is possible using also other styles than NetBeans. Eclipse, Google and Spring formatters can be used. For Eclipse formatter simply export settings from Eclipse IDE into standard file and then set Netbeans > Format: Settings Path: in VSCode Settings.

Test Explorer

NetBeans Language Server provides Test Explorer view which allows to run all tests in a project, examine the results, go to source code and run particular test.

Native Image Debugger

NetBeans Language Server allows Java like debugging of native images produced by GraalVM native-image tool. It is provided using GDB and via new Run configuration named Launch Native Image. This experimental feature works now only on Linux with certain version of GDB, see above.

In order to debug native image applications it is necessary to build such native image with debug information available. It can be done by providing following switches for native-image tool:

• -g -O0 or
• -H:Debug=2 -H:Optimize=0.

Using Native Image Maven Plugin

It is possible to use Native-Image Maven Plugin to run native-image builds for Maven projects. In this case add following <buildArgs> into plugin <configuration>:

<buildArgs>
  <buildArg>-g</buildArg>
  <buildArg>-O0</buildArg>
</buildArgs>

Setting project's Maven pom.xml to skip native-image build everytime when project is being built is a good practice.

When native image is built, including debug info then add Launch Native Image configuration to launch.json. Select it in Run & Debug activity window and press F5 to debug Java source code on native image.

Database Support

Database Explorer allows to connect to databases using appropriate JDBC drivers. Make Default Connection sets selected Database connection as default for IDE. This connection is then used by all IDE editors for SQL Code completion, or Micronaut Data queries, e.g. findByPagesGreaterThan

OCI Explorer

Oracle Cloud Infrastructure Explorer supports viewing compartments and resources available on user OCI instance. It is defined by OCI config file which has to be downloaded according to OCI instructions and saved in <users_home>/.oci/config

It is possible to add JDBC connection to Oracle Autonomous DB running in OCI using Add DB Connection menu. It downloads DB Wallet automatically.

Supported Options

• netbeans.jdkhome - path to the JDK, see dedicated section below
• netbeans.verbose - enables verbose extension logging
• netbeans.conflict.check - avoid conflicts with other Java extensions, see below

Selecting the JDK

The user projects are built, run and debugged using the same JDK which runs the Apache NetBeans Language Server. The JDK is being searched in following locations:

• netbeans.jdkhome setting (workspace then user settings)
• java.home setting (workspace then user settings)
• JDK_HOME environment variable
• JAVA_HOME environment variable
• current system path

As soon as one of the settings is changed, the Language Server is restarted.

Running Language Server per VSCode workspace or for user

It is possible to run Apache NetBeans Language Server per workspace (VSCode window). This allows separation of Language Server for given project as Language Server JVM is not shared for more VSCode open workspaces (projects). It is possible to change this in Preferences | Settings | Netbeans: Userdir. Set to local to use dedicated Language Server per workspace or set to global (this is default) to have one Language Server for all VSCode workspaces.

Conflicts with other Java Extensions

Apache NetBeans Language Server extension isn't the only Java supporting extension. To avoid duplicated code completion and other misleading clashes the extension disables certain functionality known to cause problems, this is done per Workspace.

This behavior can be disabled by setting netbeans.conflict.check setting to false.

Contributing

Read building instructions to help Apache community to improve the extension.