Can you explain what the Closable interface is and how it is used?

In Java, the interface Closable (correct name — Closeable) defines a contract for objects that can be closed, releasing associated resources such as input/output streams.

It contains one method:

void close() throws IOException;

This method is called to release resources when the object is no longer needed.

The Closeable interface is often used with the try-with-resources statement, which automatically closes resources after use:

try (BufferedReader reader = new BufferedReader(new FileReader("file.txt"))) {
    String line = reader.readLine();
    System.out.println(line);
} catch (IOException e) {
    e.printStackTrace();
}

Here, BufferedReader implements Closeable, and the close() method is called automatically at the end of the try block, helping to prevent resource leaks.