Java Community | Help. Code. Learn.•14mo ago

Week 41 — What is the purpose of the `Error` class and how is it different from `Exception`?

Question of the Week #41

What is the purpose of the Error class and how is it different from Exception?

3 Replies

Similar to Exception, instances of Error can be thrown and contain a stack trace which can be used for finding the root cause. Java throws Errors for errors that can (typically) not be recovered from. Examples of that includes OutOfMemoryError (in case an object allocation fails due to not sufficient memory being available), StackOverflowError or NoClassDefFoundError (in case a class attempted to use another class which doesn't exist or could not be loaded). On the other hand, Exceptions are used for other errors that may occur in a program. In contrast of Error, instances of Exception (unless they are an instance of RuntimeException) need to be handled when calling code that could throw them. Developers should neither create subclasses of Error nor manually throw instances of Error using the throw statement nor catch Errors. Instead, developers should try to make sure that Errors don't happen when running their applications.

📖 Sample answer from dan1st

Eric McIntyre•14mo ago

Errors are serious, unrecoverable issues that are outside the control of the application. For example an OutOfMemoryError can happen if the application needs more memory than the system can process - public class OutOfMemoryExample { public static void main(String[] args) { try { int[] array = new int[Integer.MAX_VALUE]; } catch (OutOfMemoryError error) { System.out.println("Oops! Out of memory error occurred."); error.printStackTrace(); } } } while exceptions are for handling conditions that the application could possibly recover from. A type of exception would be FileNotFoundException. import java.io.FileInputStream; import java.io.FileNotFoundException; public class FileReadExample { public static void main(String[] args) { try { FileInputStream file = new FileInputStream("nonexistent.txt"); } catch (FileNotFoundException exception) { System.out.println("Oops! File not found."); exception.printStackTrace(); } } }

Submission from kacieatdvm

Eric McIntyre•14mo ago

Error Error is type of throwable object which can occur during the execution of a program and there's no way to handle it. Programmers can only try their best to prevent it. Once it occurs the execution of the program is stopped. Few common types of errors are StackOverflowError, OutOfMemoryError

public class SomeClass {

    public static void iAmGonnaCallMyself(){
        iAmGonnaCallMyself();
    }

    public static void main(String[] args) {
        iAmGonnaCallMyself();
    }
}

public class SomeClass {

    public static void iAmGonnaCallMyself(){
        iAmGonnaCallMyself();
    }

    public static void main(String[] args) {
        iAmGonnaCallMyself();
    }
}

This code is going to produce StackOverflowError Exception Exception is also a type of throwable object but the difference is it can be caught and handled within a program. So it can prevent the program from crashing and instead can print a informative error message. Few common types of exceptions are NullPointerException, IOException

public class AnotherClass {

    public static void main(String[] args) {
        String str = null;
        try {
            System.out.println(str.length());
        } catch (NullPointerException e) {
            System.out.println("You are trying to access the length of a string which is null/not assigned yet.");
            System.out.println("Here are more details: ");
            e.printStackTrace();
        }
    }
}

public class AnotherClass {

    public static void main(String[] args) {
        String str = null;
        try {
            System.out.println(str.length());
        } catch (NullPointerException e) {
            System.out.println("You are trying to access the length of a string which is null/not assigned yet.");
            System.out.println("Here are more details: ");
            e.printStackTrace();
        }
    }
}

This code will throw a NullPointerException but we are catching and handling it properly which will prevent our program from crashing.

⭐ Submission from vampzofficial

Gaming

Programming

Week 41 — What is the purpose of the `Error` class and how is it different from `Exception`?