If you're working with 3D models, you may have encountered OBJ files, which store 3D model data including vertices, textures, and more. In Java, you can extract the vertices matrix from an OBJ file using a simple approach. Here's how you can do it:

1. Read the OBJ File: Use Java's file reading capabilities to read the contents of the OBJ file into memory. You can use BufferedReader or any other suitable method to achieve this.

2. Parse the File: Once the file is read, you'll need to parse its contents to extract the vertices information. OBJ files store vertices data in lines starting with 'v ' followed by the x, y, and z coordinates of each vertex. You can use regular expressions or simple string manipulation to identify and extract these lines.

3. Store the Vertices: As you parse the file, store the extracted vertices in a suitable data structure such as a list or array in Java. Each vertex will be represented by its x, y, and z coordinates.

4. Create the Vertices Matrix: Once you have extracted and stored all the vertices, you can organize them into a matrix. In Java, you can use a 2D array to represent the vertices matrix, where each row corresponds to a vertex and the columns represent the x, y, and z coordinates.

5. Return the Vertices Matrix: Finally, you can return the vertices matrix from your Java function, allowing other parts of your program to use the 3D model's vertices for various operations such as rendering, transformation, and more.

By following these steps, you can easily extract the vertices matrix from an OBJ file using Java. This will enable you to work with 3D model data in your Java applications and perform various operations on the vertices. Whether you're building a 3D game, visualization tool, or any other 3D-related software, having the ability to extract and work with vertices data is essential.