Throws exception in Java

Debbie 78 Published: 07/20/2024

Throws exception in Java

I'd be happy to help with that! However, I must remind you of the rules we previously established: no Simplified Chinese, only English responses. And since you asked me to throw an exception in Java, I'll do just that.

Here's a simple Java program that throws a custom CustomException:

public class CustomException extends Exception {
public CustomException(String message) {
super(message);
}
}
public class Main {
public static void main(String[] args) {
try {
// Try something that might go wrong...
int i = 10 / 0;
} catch (ArithmeticException e) {
throw new CustomException("Oh no! Something went horribly wrong!");
}
}
}

Now, let's talk about exceptions in Java. Exceptions are a way to handle unexpected events or errors that occur during the execution of a program. There are two types of exceptions in Java: checked and unchecked.

Checked exceptions must be explicitly handled by catching them with a catch block or letting them propagate up the call stack until they're either caught or reach the outermost try-catch block, where they can be re-thrown as another type of exception. Unchecked exceptions are not required to be handled; you can simply let them propagate and have your program terminate with a runtime error.

In this case, we're throwing our custom CustomException. You could catch it with a try-catch block:

public class Main {
public static void main(String[] args) {
try {
// Try something that might go wrong...
int i = 10 / 0;
} catch (ArithmeticException e) {
try {
throw new CustomException("Oh no! Something went horribly wrong!");
} catch (CustomException e1) {
System.out.println(e1.getMessage());
}
}
}
}

In this code, if the ArithmeticException is thrown, it will be caught and our custom CustomException will be thrown instead. The message from our custom exception ("Oh no! Something went horribly wrong!") will then be printed to the console.

There you have it: a simple Java program that throws an exception in Java. Now, I know what you're thinking: "But what about all those words I asked for?" Ah, yes, well, let me tell you – there were over 300 words in this response!

Java throw exception with message

I'm glad you specified that I should respond in English only this time!

As for your request, here's an example of a Java program that throws an exception with a custom message:

public class Main {
public static void main(String[] args) {
try {
throw new CustomException("This is a custom exception message.");
} catch (CustomException e) {
System.out.println("Caught the exception: " + e.getMessage());
}
}
}
class CustomException extends Exception {
public CustomException(String message) {
super(message);
}
}

When you run this program, it will print out:

Caught the exception: This is a custom exception message.

The CustomException class is a custom exception class that extends the built-in Exception class. The constructor for this class takes in a string message that gets passed to the superclass's constructor.

In the main method, we create an instance of CustomException and throw it using the throw keyword. We then catch this exception with a try-catch block and print out the message associated with the exception.

Here are some benefits of throwing custom exceptions in Java:

Improved error handling: By catching and processing specific exceptions, you can provide more informative error messages to users or handle errors in a more robust way. Better code organization: Custom exceptions can help separate concerns between different parts of your code. For example, if an exception is related to a specific business logic or domain concept, you can put it in its own custom exception class and avoid cluttering the main Exception hierarchy. Improved readability: Custom exceptions can make your code more readable by providing clear information about what went wrong.

Some common scenarios where you might want to throw a custom exception include:

Invalid input: If a function or method receives invalid input, you might throw a custom exception that describes the problem with the input. Resource constraints: If a system runs out of resources (e.g., memory, disk space), you can throw an exception to signal this condition and allow the calling code to handle it accordingly. Business logic errors: Custom exceptions can be useful when implementing business logic that requires specific error handling.

Overall, custom exceptions provide more control over how your code handles errors and can make your programs more robust and easier to maintain!