Custom AutoCloseable in Java: Explanation & Practice

Problem summary

Create a Connection class that implements AutoCloseable and automatically closes in try-with-resources.

Starter code

class Connection implements AutoCloseable {
    private String name;
    
    public Connection(String name) {
        this.name = name;
        System.out.println(name + " opened");
    }
    
    public void execute() {
        System.out.println(name + " executing");
    }
    
    @Override
    public void close() {
        // Print closing message
    }
}

public class Main {
    public static void main(String[] args) {
        try (Connection conn = new Connection("DB")) {
            conn.execute();
        }
        System.out.println("Done");
    }
}

Expected output and test cases

• Resource auto-closed

  DB opened
  DB executing
  DB closed
  Done

Hints

1. Implement close() method
2. close() is called automatically
3. Even if exception occurs in try block

Related Exception Handling exercises

• Practice Graceful Degradation in Java
• Practice Exception Chaining in Java
• Practice Suppressed Exceptions in Java

Practice all Exception Handling exercises · Run this idea in the Java compiler