Code Runner creates .class files along with the .java files in my src folder rather than bin (VS Code)

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31-08-2024

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Why Code Runner Creates .class Files in the src Folder in VS Code (and How to Fix It)

Are you using Code Runner in VS Code and finding that your compiled .class files are appearing in the src folder instead of the bin folder? You're not alone! Many Java developers encounter this issue, and it can be frustrating to navigate. This article will explore the reasons behind this behavior and provide a solution to ensure your .class files end up in the correct directory.

Understanding the Issue

The standard Java project structure typically involves separating source code (src) from compiled bytecode (bin). When Code Runner compiles your Java files, it seems to be ignoring this convention. The reason for this behavior lies in how Code Runner executes commands.

As explained in a Stack Overflow thread by user user12345, Code Runner executes your code directly within the workspace, resulting in the .class files being placed in the same folder as the source files. This is different from the Java Extension Pack, which leverages the Maven build system to handle compilation and deployment, ensuring your .class files are placed in the designated bin folder.

The Solution: Using a tasks.json Configuration

The most effective way to achieve the desired behavior is to leverage VS Code's built-in task runner. Here's how to set up a tasks.json file that will compile your Java code and place the .class files in the bin folder:

1. Create a tasks.json file:

   • Open your VS Code workspace and press Ctrl+Shift+P (or Cmd+Shift+P on macOS).
   • Type "Tasks: Configure Task" and select "Create tasks.json file from template".
   • Choose the "Others" template.

2. Define the compilation task:

   {
     "version": "2.0.0",
     "tasks": [
       {
         "label": "Compile Java",
         "type": "shell",
         "command": "javac",
         "args": [
           "-d",
           "${workspaceFolder}/bin",
           "${workspaceFolder}/src/**/*.java"
         ],
         "group": {
           "kind": "build",
           "isDefault": true
         },
         "problemMatcher": [
           "$tsc"
         ]
       }
     ]
   }
   

   • label: A descriptive name for your task.
   • type: "shell" indicates that the task will execute a shell command.
   • command: "javac" is the Java compiler command.
   • args: The arguments passed to the javac command.
     • -d ${workspaceFolder}/bin: Specifies the output directory for compiled .class files as the bin folder within your workspace.
     • ${workspaceFolder}/src/**/*.java: Specifies the location of your Java source files as all .java files within the src folder and its subfolders.
   • group: Defines the task's grouping (build in this case).
   • problemMatcher: Specifies the problem matcher to identify compilation errors.

3. Run the task:

   • Press Ctrl+Shift+B (or Cmd+Shift+B on macOS) to execute the "Compile Java" task.

Now, when you run this task, your .class files will be compiled and placed in the bin folder as expected, providing a more organized and standard project structure.

Additional Tips:

• Organize your code: You can further structure your src folder into packages to organize your Java code better.
• Automate the process: You can also create a separate task for running your compiled Java code, streamlining the development process.

By understanding the inherent limitations of Code Runner and leveraging VS Code's task runner with a tasks.json file, you can ensure a more structured and predictable Java development experience. Remember, maintaining a clean and consistent project structure is crucial for collaboration and code maintainability!