Provides Java support using the javac API. Requires that you have Java 8 installed on your system.
Install from the VS Code marketplace
The presence of a javaconfig.json file indicates that
its parent directory is the root of a Java module.
javaconfig.json looks like:
{
"sourcePath": ["relative/path/to/source/root", ...],
"classPathFile": "file-with-classpath-as-contents.txt",
"outputDirectory": "relative/path/to/output/root"
}
The classpath is contained in a separate file,
in the format entry.jar:another-entry.jar.
This file is usually generated by a build tool like maven.
You can configure maven to output the current classpath to a file, classpath.txt, where Visual Studio Code will find it.
Set the source path, and get the class path from a file:
{
"sourcePath": ["src/main/java"],
"classPathFile": "classpath.txt",
"outputDirectory": "target"
}
Configure maven to output classpath.txt
<project ...>
...
<build>
...
<plugins>
...
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.9</version>
<executions>
<execution>
<id>build-classpath</id>
<phase>generate-sources</phase>
<goals>
<goal>build-classpath</goal>
</goals>
</execution>
</executions>
<configuration>
<outputFile>classpath.txt</outputFile>
</configuration>
</plugin>
</plugins>
</build>
</project>
Ignore classpath.txt, since it will be different on every host
classpath.txt
...
A java process that does the hard work of parsing and analyzing .java source files.
pom.xml (maven project file)
src/ (java sources)
repo/ (tools.jar packaged in a local maven repo)
target/ (compiled java .class files, .jar archives)
target/fat-jar.jar (single jar that needs to be distributed with extension)
"Glue code" that connects to the external java process using a network port, and implements various features of the Visual Studio Code extension API.
package.json (node package file)
tsconfig.json (typescript compilation configuration file)
tsd.json (project file for tsd, a type definitions manager)
lib/ (typescript sources)
out/ (compiled javascript)
This extension consists of an external java process, and some typescript glue code that talks to the VS Code API. The typescript glue code communicates with the external java process using a randomly assigned network port.
In the future, the javac service process could be used separately by other tools that need Java code insight.
The java service process uses the implementation of the Java compiler in tools.jar, which is a part of the JDK. When VS Code needs to lint a file, perform autocomplete, or some other task that requires Java code insight, the java service process invokes the Java compiler programatically, then intercepts the data structures the Java compiler uses to represent source trees and types.
The Java compiler isn't designed for incremental parsing and analysis. However, it is extremely fast, so recompiling a single file gives good performance, as long as we don't also recompile all of its dependencies. We accomplish this by maintaining a single copy of the Java compiler in memory at all times. When we want to recompile a file, we clear that one file from the internal caches of the Java compiler, and then rerun the compiler.
If you have multiple javaconfig.json files in different subdirectories of your project, the parent directory of each javaconfig.json will be treated as a separate java root. A separate java service process will be started for each javaconfig.json.
The java service process will output a log file with a name like 'javac-services.0.log' in your project directory.
If you have npm and maven installed, you should be able to install locally using
npm install -g vsce
npm install
./scripts/install.sh