try-with-resources (AutoCloseable)
Use try-with-resources and AutoCloseable to manage resources safely.
try-with-resources (AutoCloseable) is a free Java Academy lesson on CoddyKit. This is lesson 2 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, and your progress syncs across the web and the CoddyKit app. The Java Academy course includes 3 lessons in total.
Intro
Resources like files or sockets need closing. try-with-resources closes them automatically if they implement AutoCloseable.
AutoCloseable concept
Any class that implements AutoCloseable can be used. Common ones include FileReader, BufferedReader, and JDBC connections.
Code: FileReader auto-close
This FileReader is closed automatically after the try block ends, even if an exception occurs.
public class Main {
public static void main(String[] args) {
try (java.io.FileReader fr = new java.io.FileReader("test.txt")) {
int ch = fr.read();
System.out.println("First char code=" + ch);
} catch (java.io.IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Multiple resources
You can open multiple resources in one try. They will be closed in reverse order automatically.
Code: two resources
Both BufferedReader and PrintWriter are closed automatically, in reverse order of creation.
public class Main {
public static void main(String[] args) {
try (java.io.BufferedReader br = new java.io.BufferedReader(new java.io.FileReader("test.txt"));
java.io.PrintWriter pw = new java.io.PrintWriter("out.txt")) {
String line = br.readLine();
pw.println(line);
} catch (java.io.IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Code: custom AutoCloseable
You can implement AutoCloseable yourself. The close() method will be called automatically.
public class Main {
static class MyRes implements AutoCloseable {
public void use() { System.out.println("Using resource"); }
public void close() { System.out.println("Closed resource"); }
}
public static void main(String[] args) {
try (MyRes r = new MyRes()) {
r.use();
}
}
}
try-with-resources check
Quick check: What is the main benefit of try-with-resources?
Recap
Recap: try-with-resources works with AutoCloseable. It ensures safe cleanup of files, streams, and custom resources.
Learn Java with an AI tutor — free
Write and run real code in your browser, get instant help from a 24/7 AI tutor, and pick up where you left off on the web or in the app.
- Courses
- 104
- Lessons
- 374
Frequently Asked Questions
Is the “try-with-resources (AutoCloseable)” lesson free?
Yes — the full text of “try-with-resources (AutoCloseable)” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO. The Java Academy course includes 3 lessons in total.
What will I learn in “try-with-resources (AutoCloseable)”?
Use try-with-resources and AutoCloseable to manage resources safely. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Java Academy?
No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 2 of 3.
How long does the “try-with-resources (AutoCloseable)” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Java Academy lesson?
Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Throwing & Custom Exceptions
- try-with-resources (AutoCloseable)
- Defensive Programming