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---
title: "Java Finally Block"
description: "Learn how to use the finally block in Java exception handling to execute code that must run regardless of whether an exception occurs or not."

---

Java Finally Block

Introduction

Exception handling is a critical aspect of writing robust Java applications. While try and catch blocks handle exceptions when they occur, Java provides another important component called the finally block. The finally block contains code that always executes regardless of whether an exception occurs or not.

In this tutorial, you'll learn:

• What the finally block is and why it's important
• How to use the finally block with try-catch statements
• Common use cases for the finally block
• Best practices and potential pitfalls

What is the Finally Block?

The finally block follows a try block or a try-catch block and contains code that will be executed regardless of whether an exception is thrown or caught. This makes it perfect for cleanup operations that should happen no matter what.

Here's the basic syntax:

java

try {
    // Code that might throw an exception
} catch (ExceptionType e) {
    // Code to handle the exception
} finally {
    // Code that always executes
}

You can also use a finally block without a catch block:

java

try {
    // Code that might throw an exception
} finally {
    // Code that always executes
}

Why Use the Finally Block?

The finally block serves several important purposes:

1. Resource cleanup: Releasing resources like file handles, database connections, or network sockets
2. State consistency: Ensuring your program's state remains consistent regardless of exceptions
3. Code reuse: Avoiding duplicate cleanup code in both the try and catch blocks

Basic Example of Using Finally

Let's start with a simple example to understand how the finally block works:

java

public class FinallyDemo {
    public static void main(String[] args) {
        try {
            System.out.println("Inside try block");
            int result = 10 / 0; // This will throw ArithmeticException
            System.out.println("This won't be printed");
        } catch (ArithmeticException e) {
            System.out.println("Exception caught: " + e.getMessage());
        } finally {
            System.out.println("Finally block always executes");
        }
        
        System.out.println("After try-catch-finally");
    }
}

Output:

Inside try block
Exception caught: / by zero
Finally block always executes
After try-catch-finally

As you can see, even though an exception occurred, the finally block still executed before the program continued.

Finally Block Without Catch

You can use a finally block without a catch block when you want to ensure certain code executes but don't want to handle the exception in the current method:

java

public class FinallyWithoutCatch {
    public static void main(String[] args) {
        try {
            riskyOperation();
        } finally {
            System.out.println("Cleanup code in finally block");
        }
    }
    
    public static void riskyOperation() throws RuntimeException {
        throw new RuntimeException("Something went wrong!");
    }
}

Output:

Cleanup code in finally block
Exception in thread "main" java.lang.RuntimeException: Something went wrong!
    at FinallyWithoutCatch.riskyOperation(FinallyWithoutCatch.java:10)
    at FinallyWithoutCatch.main(FinallyWithoutCatch.java:4)

Notice how the finally block executed before the exception propagated up the call stack.

Common Use Case: Resource Management

One of the most common uses of the finally block is for resource management. Here's an example with file handling:

java

import java.io.FileReader;
import java.io.IOException;

public class FileResourceExample {
    public static void main(String[] args) {
        FileReader reader = null;
        try {
            reader = new FileReader("example.txt");
            // Read from the file...
            char[] buffer = new char[1024];
            reader.read(buffer);
            System.out.println("File content: " + new String(buffer));
        } catch (IOException e) {
            System.out.println("Error reading file: " + e.getMessage());
        } finally {
            // Close the file in the finally block to ensure it happens
            // even if an exception occurs
            try {
                if (reader != null) {
                    reader.close();
                    System.out.println("FileReader closed successfully");
                }
            } catch (IOException e) {
                System.out.println("Error closing file: " + e.getMessage());
            }
        }
    }
}

In the example above, the finally block ensures that the file is closed regardless of whether the file was read successfully or an exception occurred.

Modern Alternative: Try-with-Resources

Since Java 7, you can use the try-with-resources statement for automatic resource management, which often eliminates the need for explicit finally blocks:

java

import java.io.FileReader;
import java.io.IOException;

public class TryWithResourcesExample {
    public static void main(String[] args) {
        try (FileReader reader = new FileReader("example.txt")) {
            // Read from the file...
            char[] buffer = new char[1024];
            reader.read(buffer);
            System.out.println("File content: " + new String(buffer));
        } catch (IOException e) {
            System.out.println("Error reading file: " + e.getMessage());
        }
        // No finally block needed - resources are automatically closed
    }
}

The try-with-resources statement automatically calls close() on resources that implement the AutoCloseable interface, making your code cleaner and less error-prone.

Control Flow with Finally

The finally block affects the control flow in your program in some important ways:

java

public class FinallyReturnExample {
    public static void main(String[] args) {
        int result = getValue();
        System.out.println("Result: " + result);
    }
    
    public static int getValue() {
        try {
            return 1; // This return statement is reached
        } finally {
            System.out.println("Finally executes before the method returns");
            // Note: adding a return statement here would override the previous return!
        }
    }
}

Output:

Finally executes before the method returns
Result: 1

As demonstrated, the finally block executes even when a return statement is encountered in the try block. This behavior is important to understand to avoid unexpected results.

Finally Block and Exceptions

If an exception is thrown within the finally block, it will override any exception thrown in the try or catch blocks:

java

public class FinallyExceptionExample {
    public static void main(String[] args) {
        try {
            exceptionTest();
        } catch (Exception e) {
            System.out.println("Caught exception: " + e.getMessage());
        }
    }
    
    public static void exceptionTest() throws Exception {
        try {
            System.out.println("In try block");
            throw new Exception("Exception from try block");
        } catch (Exception e) {
            System.out.println("In catch block");
            throw new Exception("Exception from catch block");
        } finally {
            System.out.println("In finally block");
            throw new Exception("Exception from finally block");
        }
    }
}

Output:

In try block
In catch block
In finally block
Caught exception: Exception from finally block

Notice that only the exception from the finally block is propagated, while the exceptions from the try and catch blocks are suppressed.

When Finally Doesn't Execute

There are a few rare situations where the finally block doesn't execute:

1. If the JVM exits during execution of the try or catch block (e.g., by calling System.exit())
2. If the thread executing the try or catch block is interrupted or killed
3. If an error occurs that crashes the JVM

Example with System.exit():

java

public class FinallyNotExecutingExample {
    public static void main(String[] args) {
        try {
            System.out.println("Inside try block");
            System.exit(0); // JVM will exit, finally won't execute
        } finally {
            System.out.println("This won't be printed");
        }
    }
}

Output:

Inside try block

Best Practices for Using Finally Blocks

1. Keep finally blocks short and focused on resource cleanup and state management
2. Avoid throwing exceptions from within finally blocks when possible
3. Don't use control flow statements like return, continue, or break in finally blocks
4. Consider using try-with-resources instead of explicit finally blocks when dealing with closeable resources
5. Don't perform complex operations in finally blocks that might fail

Flow of Execution (Visualization)

Summary

The finally block is a powerful feature in Java's exception handling mechanism that ensures certain code always executes, regardless of exceptions. Key points to remember:

• The finally block executes whether an exception is thrown or not
• It executes even if there's a return statement in the try or catch blocks
• It's commonly used for resource cleanup and maintaining state consistency
• For resource management, the try-with-resources statement is often a better alternative
• Exceptions in the finally block override exceptions in try or catch blocks

By mastering the finally block, you can write more robust Java applications with proper resource management and error handling.

Exercises

1. Write a program that uses a finally block to ensure a file is always closed, even if an exception occurs during reading.
2. Modify the program above to use the try-with-resources statement instead.
3. Create a program that demonstrates how a finally block executes even when a method returns from within a try block.
4. Write a program that shows how exceptions in a finally block override exceptions from try and catch blocks.

Additional Resources

• Java Documentation on Exceptions
• Java Exception Handling Best Practices
• Try-with-resources Statement