Java try-with-resources

August 4, 2023

What is try with resources?

Java try-with-resources is a language feature introduced in Java 7 that simplifies the handling of resources such as files, database connections, and network sockets.

It automatically closes the resources when they are no longer needed, even if an exception occurs, reducing the chance of resource leaks and improving code readability.

To understand the more about Java try with resources, Read the Complete Article.

java try-with-resources multiple

You can declare and initialize multiple resources within the same try-with-resources statement. To do so, simply separate each resource declaration with a semicolon.
Each resource declaration must be a valid expression that creates an object of a class that implements the AutoCloseable interface.
The resources are closed in the opposite order in which they are declared. That is, the last resource declared is closed first, and so on.
The try-with-resources statement can still include a catch and/or finally block (optional) to handle exceptions and perform cleanup tasks.
If an exception occurs during the closing of one of the resources, the exceptions are added to the original exception thrown by the try block and are referred to as “suppressed” exceptions.

Suppressed Exceptions

Suppressed exceptions are exceptions that occur during the closing of a resource in Java's try-with-resources statement.

Suppressed exceptions are important because they can provide additional information about what went wrong during the execution of the code.

Advantages of using try-with-resources:

Automatic resource management: try-with-resources automatically takes care of closing resources such as files, database connections, and network sockets. This helps to prevent resource leaks, as the resources are always properly closed even in the event of an exception.

Improved readability: Because try-with-resources can reduce the amount of boilerplate code needed to manage resources, it can also improve the readability of the code by making it easier to focus on the main logic of the program.

Cleaner and more concise code: By eliminating the need for explicit finally blocks to close resources, try-with-resources can help to make code cleaner and more concise. The resources are declared within the try block and are automatically closed when the block finishes executing.

Reduced likelihood of errors: Since try-with-resources simplifies the management of resources, there is less code to write and fewer opportunities for errors to creep in.

Feature	Description
Syntax	The try-with-resources statement consists of a try block, one or more resource declarations, and a catch and/or finally block (optional).
Suppressed exceptions	Try-with-resources can capture and handle suppressed exceptions that occur during the closing of resources.
Improved readability	Try-with-resources can improve the readability of the code by making it easier to focus on the main logic of the program.
Cleaner and more concise code	Try-with-resources eliminates the need for explicit finally blocks to close resources, making code cleaner and more concise.
Automatic resource management	The try-with-resources statement automatically closes resources such as files, network sockets, and database connections when they are no longer needed.

Introduction to java

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Switch Statement in Java

Abstraction in Java

Example 1: Java Try with resources with mutiple resources.

Run

import java.io.*;

public class Main {
    public static void main(String[] args) {
        try (BufferedReader reader = new BufferedReader(new FileReader("input.txt"));
             BufferedWriter writer = new BufferedWriter(new FileWriter("output.txt"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                writer.write(line);
                writer.newLine();
            }
        } catch (IOException e) {
            System.err.println("Error: " + e.getMessage());
        }
    }
}

Output

Error reading file: example.txt (No such file or directory)

Explanation:

In this program, we declare and initialize two resources within the parentheses of the try statement: a BufferedReader for reading data from the input.txt file, and a BufferedWriter for writing data to the output.txt file. We then read each line of data from the input file and write it to the output file. Finally, the resources are automatically closed at the end of the try block.

Example 2: Java Try with resources

Run

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

 
public class Main
{
  
public static void main (String[]args)
  {
    
try (BufferedReader reader =
	  new BufferedReader (new FileReader ("example.txt")))
    {
      
String line = null;
      
while ((line = reader.readLine ()) != null)
	{
	  
System.out.println (line);
	
}
    
}
    catch (IOException e)
    {
      
System.err.println ("Error reading file: " + e.getMessage ());
    
}
  
}

}

Output

Error reading file: example.txt (No such file or directory)

Explanation:

we create a BufferedReader object for reading a file "example.txt". The try-with-resources statement automatically closes the reader object when it is no longer needed. If an exception occurs while reading the file, the catch block handles it and prints an error message.

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Java try-with-resources

What is try with resources?

java try-with-resources multiple

Advantages of using try-with-resources:

Example 1: Java Try with resources with mutiple resources.

Output

Example 2: Java Try with resources

Output

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