Java Debugging in Visual Studio Code

• Maven + Jetty version

Getting Started

Install Extension

• Microsoft, Java Extension Pack, https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-pack

Setting the JDK

• Temurin, https://adoptium.net/
• Amazon, Corretto 17, https://docs.aws.amazon.com/corretto/latest/corretto-17-ug/downloads-list.html
• Azule Systems, Zule OpenJDK, https://www.azul.com/downloads/
• OpenJDK, https://jdk.java.net/
• Red Hat, OpenJDK, https://developers.redhat.com/products/openjdk/download/

The path to the Java Development Kit is searched in the following order:

• the java.home setting in VS Code settings (workspace then user settings)
• the JDK_HOME environment variable
• the JAVA_HOME environment variable
• on the current system path

Gradle Configurations

• build.gradle

repositories {
    mavenCentral()
}

apply plugin: 'java'

sourceCompatibility = 17
targetCompatibility = 17

compileTestJava {
    options.compilerArgs += '-parameters'
}

test {
    useJUnitPlatform()
}

dependencies {
    testImplementation('org.junit.jupiter:junit-jupiter:5.9.2')
}

Build Configurations

• .vscode/tasks.json

{
  "version": "2.0.0",
  "echoCommand": true,
  "command": "./gradlew",
  "presentation": {
    "echo": true,
    "reveal": "always",
    "focus": false,
    "panel": "shared"
  },
  "tasks": [
    {
      "label": "compileJava",
      "type": "shell"
    },
    {
      "label": "test",
      "type": "shell",
      "group": {
        "kind": "test",
        "isDefault": true
      }
    },
    {
      "label": "clean",
      "type": "shell"
    },
    {
      "label": "build",
      "type": "shell",
      "group": {
        "kind": "build",
        "isDefault": true
      }
    }
  ]
}

Java Debugger Configurations

• .vscode/launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "java",
            "name": "Debug (Launch)",
            "request": "launch",
            "cwd": "${workspaceFolder}",
            "console": "internalConsole",
            "stopOnEntry": false,
            "preLaunchTask": "compileJava",
            "mainClass": "com.vscode.demo.Main",
            "args": ""
        }
    ]
}

Java programming

• src/main/java/com/vscode/demo/Main.java

package com.vscode.demo;

import java.util.Objects;
import java.util.stream.Stream;

public class Main {

    public static void main(String[] args) {
        System.out.println("Hello VS Code!");

        Stream.of("React", "Angular", "Vue")
            .filter(x -> Objects.equals(x, "React"))
            .forEach(System.out::println);
    }

}

• src/main/java/com/vscode/demo/MainTest.java

package com.vscode.demo;

import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;

@Tag("main")
class MainTest {

    @Test
    @DisplayName("VS Code JUnit 5 test")
    void testMain() {

        // arrange
        final List<String> list = Arrays.asList("React", "Angular", "Vue");

        // act
        final String actual = list.stream()
            .filter(x -> Objects.equals(x, "React"))
            .findFirst()
            .orElseThrow(IllegalArgumentException::new);

        // assert
        assertEquals("React", actual, () -> "Main Succeed");
    }

}

Debugging

1. Open Main.java
2. Press F5

Testing

1. Open Command Pallete cmd+shift+p (macOS) or ctrl+shift+p (Windonws/Linux)
2. Tasks Run Test Task
3. test

References

1. Visual Studio Code, Java in VS Code, https://code.visualstudio.com/docs/languages/java
2. GitHub, Language Support for Java(TM) by Red Hat, https://github.com/redhat-developer/vscode-java
3. Visual Studio Code, Integrate with External Tools via Tasks, Variable substitution, https://code.visualstudio.com/Docs/editor/tasks#_variable-substitution
4. Gradle, Chapter 47. The Java Plugin, https://docs.gradle.org/current/userguide/java_plugin.html
5. GitHub, JUnit 5 Samples, https://github.com/junit-team/junit5-samples
6. Gradle, Gradle 4.6 Release Notes - JUnit 5 support, https://docs.gradle.org/4.6/release-notes.html#junit-5-support