How do I change the project type in Eclipse?

Changing the project type in Eclipse typically involves modifying its project properties or natures, which dictates how Eclipse builds and manages the project. This is especially common when working with C/C++ projects or when converting general projects to specific frameworks like Maven.

How to Change the Project Type in Eclipse

Modifying your project's type in Eclipse primarily depends on whether you're adjusting a C/C++ project's build target (e.g., executable vs. library) or altering a project's fundamental nature (e.g., converting a Java project to a Maven project).

1. Understanding Eclipse Project Types and Natures

Eclipse projects are defined by their "natures" and build configurations. A project nature determines the tooling available for the project (e.g., Java Development Tools for Java projects, C/C++ Development Tools for C/C++ projects). The "project type" can refer to these natures or, more granularly within a specific nature like C/C++, to the target output (executable, library, etc.).

2. Changing C/C++ Project Types in Eclipse CDT

For projects utilizing the Eclipse C/C++ Development Tools (CDT), you have granular control over the build target type. This is particularly relevant as it directly influences the output binaries and how Eclipse manages the build process.

To change the type of a C/C++ project:

Right-Click Your Project: In the Project Explorer view, right-click on the C/C++ project you wish to modify.
Open Properties: Select Properties from the context menu. This will open the project's properties dialog.
Navigate to C/C++ Build Settings: In the left-hand pane of the Properties dialog, expand C/C++ Build and then click on Settings.
Adjust Build Artifact Type:
- Go to the Tool Chain Editor tab (or Build Artifact depending on your CDT version).
- Locate the Artifact type dropdown or similar setting, which allows you to define the output.

Common C/C++ Project Types and Makefile Generation

Eclipse CDT simplifies development by automatically generating makefiles for various common project types. This means you don't typically need to write or manage Makefiles manually for these targets.

Here's a breakdown of common C/C++ project types and their makefile generation:

Project Type	Description	Makefile Generation
Executable	Creates a standard executable application.	Automatic
Shared Library	Builds a dynamically linked library (e.g., `.so` on Linux, `.dll` on Windows).	Automatic
Static Library	Compiles a statically linked library (e.g., `.a` on Linux, `.lib` on Windows).	Automatic
Several specific types marked with rhombuses	Other specialized build targets or project templates, often indicated by specific icons in the UI.	Automatic

By selecting one of these types, Eclipse CDT configures the build system to produce the desired output artifact, handling the underlying makefile structure automatically. For more details on CDT project setup, refer to the Eclipse CDT Documentation.

3. Converting General Project Natures

Sometimes, "changing project type" means adding or removing a specific nature, such as converting a basic Java project into a Maven project, or adding a JavaScript nature to a web project.

To convert or add a project nature:

Right-Click Your Project: In the Project Explorer, right-click on the project.
Go to Configure: Hover over Configure in the context menu.
Select Conversion Option: You will often see options like:
- Convert to Maven Project
- Add Java Nature / Remove Java Nature
- Convert to Faceted Form... (for web projects to manage facets like Dynamic Web Module, JPA, etc.)
- Other specific options depending on the installed plugins (e.g., Spring, Gradle).
Follow Prompts: If applicable, follow any wizards that appear to complete the conversion.

This process modifies the .project file within your project directory, which Eclipse uses to determine how to treat the project.

Practical Tips and Considerations

Backup Your Project: Always consider backing up your project before making significant changes to its type or configuration.
Clean and Rebuild: After changing project types or natures, it's often a good practice to perform a Project > Clean... followed by a Project > Build All to ensure Eclipse rebuilds everything with the new settings.
Check Build Settings: Verify that compiler paths, include directories, and linker settings are still correct after a type change, especially for C/C++ projects.
Installed Plugins: The options available for changing project types or natures heavily depend on the Eclipse plugins you have installed. Ensure you have the necessary plugins (e.g., CDT for C/C++, M2E for Maven) if an option is missing.

By understanding these methods, you can effectively manage and change your project types within Eclipse to suit your development needs.