Debugging Spring Boot Applications in Visual Studio Code

Debugging Spring Boot Applications in Visual Studio Code | Generated by AI

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To debug a Maven Spring Boot project in Visual Studio Code (VSCode), you can follow these straightforward steps to set up and run your application in debug mode. This guide assumes you have a basic Maven Spring Boot project with a pom.xml file and a main class annotated with @SpringBootApplication. Here’s how to do it:

Step 1: Install Necessary Extensions

Before you begin, ensure that VSCode is equipped with the required extensions for Java and Spring Boot development:

Java Extension Pack: This includes essential tools like Language Support for Java by Red Hat, which provides debugging capabilities, along with other utilities for Java development.
Spring Boot Extension Pack: This pack enhances Spring Boot development with features like the Spring Boot Dashboard, Spring Boot Tools, and more.

To install these:

Open VSCode.
Go to the Extensions view (Ctrl+Shift+X or Cmd+Shift+X on macOS).
Search for “Java Extension Pack” and “Spring Boot Extension Pack,” then click Install for each.

Step 2: Open Your Maven Spring Boot Project

Launch VSCode and open your project folder by selecting File > Open Folder and choosing the directory containing your pom.xml file.
VSCode will detect the pom.xml, and the Java Extension Pack will automatically index the project and resolve dependencies. This may take a moment, so wait until the process completes (you’ll see progress in the bottom-right status bar).

Step 3: Create or Edit the `launch.json` File

To configure debugging, you need to set up a launch.json file in VSCode:

Open the Run and Debug view by clicking the bug-and-play icon in the sidebar or pressing Ctrl+Shift+D.
If no debug configuration exists, click “create a launch.json file”. If one already exists, click the gear icon to edit it.
When prompted, select Java as the environment. VSCode will generate a default launch.json file in a .vscode folder within your project.
Add or modify a debug configuration for your Spring Boot application. Here’s an example configuration:
```
 {
     "type": "java",
     "name": "Debug Spring Boot",
     "request": "launch",
     "mainClass": "com.example.demo.DemoApplication",
     "projectName": "demo"
 }
```
- Replace "com.example.demo.DemoApplication" with the fully qualified name of your main class (e.g., com.yourcompany.yourapp.YourApplication).
- Replace "demo" with your project’s name, typically the <artifactId> from your pom.xml.
Save the launch.json file.

Optional: Add Arguments

If your application requires specific arguments (e.g., Spring profiles), you can include them:

{
    "type": "java",
    "name": "Debug Spring Boot",
    "request": "launch",
    "mainClass": "com.example.demo.DemoApplication",
    "projectName": "demo",
    "args": "--spring.profiles.active=dev"
}

Step 4: Start Debugging

In the Run and Debug view, select “Debug Spring Boot” from the dropdown menu at the top.
Click the green play button (or press F5) to launch the application in debug mode.
VSCode will compile the project using Maven, start the Spring Boot application, and attach the debugger automatically.

Step 5: Set Breakpoints and Debug

Open a Java file in your project (e.g., a controller or service class).
Set breakpoints by clicking in the gutter to the left of the line numbers, where a red dot will appear.
Interact with your application (e.g., via a browser or API client). When execution hits a breakpoint, VSCode will pause, allowing you to:
- Inspect variables in the Variables panel.
- Step through code using controls like Step Over (F10), Step Into (F11), or Continue (F5).
- View the call stack and more in the debug sidebar.

Alternative Methods

While the launch.json method is recommended for its flexibility, you can also debug using:

Maven View:
1. Open the Maven view in the sidebar (look for the “M” icon or enable it via Extensions).
2. Expand your project, navigate to spring-boot under Plugins, right-click spring-boot:run, and select Debug.
3. The application will start, and the debugger will attach.
Spring Boot Dashboard:
1. Open the Spring Boot Dashboard (usually in the Explorer view or via the command palette: Spring Boot Dashboard).
2. Locate your application, right-click it, and select Debug (if available).

Prerequisites and Notes

Ensure Maven is installed on your system and accessible via the command line, or rely on VSCode’s embedded Maven (configured via settings if needed).
Verify your project builds successfully (mvn clean install) to avoid runtime errors during debugging.
Use a compatible Java version as specified in your pom.xml (e.g., via <java.version>).

By following these steps, you can effectively debug your Maven Spring Boot project in VSCode, leveraging its powerful debugging tools to identify and resolve issues in your code.

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