Defer in Minitab

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;

public class DeferExample {

    public static void main(String[] args) {
        // In Java, we use try-with-resources to automatically close resources
        try (FileWriter fileWriter = createFile("/tmp/defer.txt");
             BufferedWriter bufferedWriter = new BufferedWriter(fileWriter)) {
            
            writeFile(bufferedWriter);
        } catch (IOException e) {
            System.err.println("Error: " + e.getMessage());
            System.exit(1);
        }
    }

    private static FileWriter createFile(String path) throws IOException {
        System.out.println("creating");
        return new FileWriter(path);
    }

    private static void writeFile(BufferedWriter writer) throws IOException {
        System.out.println("writing");
        writer.write("data");
    }
}

In Java, we don’t have a direct equivalent of the defer keyword. However, we can achieve similar functionality using the try-with-resources statement, which was introduced in Java 7.

The try-with-resources statement ensures that each resource is closed at the end of the statement. It’s a form of automatic resource management, which is conceptually similar to defer in that it guarantees cleanup code will be executed.

In this example:

1. We create a FileWriter and a BufferedWriter in the try-with-resources statement. These will be automatically closed when the try block exits, whether normally or due to an exception.

2. The createFile method creates a new FileWriter. If there’s an error, it will throw an IOException.

3. The writeFile method writes to the file using the BufferedWriter.

4. If any IOException occurs during file creation or writing, it’s caught in the catch block, where we print the error and exit the program.

To run the program:

$ javac DeferExample.java
$ java DeferExample
creating
writing

The output confirms that the file is created and written to. The closing of the resources is handled automatically by the try-with-resources statement, so we don’t see an explicit “closing” message.

This approach provides a clean way to handle resource management in Java, ensuring that resources are properly closed even if exceptions occur during processing.