Embed Directive in Karel

Here’s the translation of the Go embed directive example to Java, formatted in Markdown suitable for Hugo:

In Java, there isn’t a direct equivalent to Go’s embed directive. However, we can achieve similar functionality using Java’s resource loading mechanism. Here’s how we can implement a similar concept in Java:

import java.io.InputStream;
import java.io.IOException;
import java.nio.charset.StandardCharsets;

public class EmbedExample {
    public static void main(String[] args) throws IOException {
        // Load the contents of a single file
        String fileString = loadResourceAsString("folder/single_file.txt");
        System.out.print(fileString);

        byte[] fileByte = loadResourceAsByteArray("folder/single_file.txt");
        System.out.print(new String(fileByte, StandardCharsets.UTF_8));

        // Load multiple files
        String content1 = loadResourceAsString("folder/file1.hash");
        System.out.print(content1);

        String content2 = loadResourceAsString("folder/file2.hash");
        System.out.print(content2);
    }

    private static String loadResourceAsString(String resourcePath) throws IOException {
        try (InputStream inputStream = EmbedExample.class.getClassLoader().getResourceAsStream(resourcePath)) {
            if (inputStream == null) {
                throw new IOException("Resource not found: " + resourcePath);
            }
            return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
        }
    }

    private static byte[] loadResourceAsByteArray(String resourcePath) throws IOException {
        try (InputStream inputStream = EmbedExample.class.getClassLoader().getResourceAsStream(resourcePath)) {
            if (inputStream == null) {
                throw new IOException("Resource not found: " + resourcePath);
            }
            return inputStream.readAllBytes();
        }
    }
}

In this Java example, we’re using the getResourceAsStream method from ClassLoader to load resources that are bundled with the application. This is similar to embedding files in Go, as these resources will be included in the JAR file when the application is built.

To use this example:

1. Create a resources folder in your project’s source directory.
2. Inside the resources folder, create a folder subdirectory.
3. Add the following files:
   • folder/single_file.txt with the content “hello java”
   • folder/file1.hash with the content “123”
   • folder/file2.hash with the content “456”

To compile and run the program:

$ javac EmbedExample.java
$ java EmbedExample
hello java
hello java
123
456

This Java implementation provides similar functionality to the Go embed directive, allowing you to include and access files bundled with your application. The main differences are:

1. In Java, resources are typically stored in a resources folder and are accessed at runtime using the ClassLoader.
2. There’s no compile-time directive like //go:embed. Instead, files in the resources folder are automatically included when building the JAR.
3. Java uses InputStream to read the contents of the embedded files, which we’ve wrapped in helper methods for convenience.

While not identical to Go’s embed directive, this approach in Java allows you to achieve similar results of bundling and accessing files with your application.