Question

If you are writing a custom exception class, how can you make sure it is checked? How can you make sure it is unchecked?

Short answer

Answer: The two types of exceptions in Java are checked and unchecked exceptions. Checked exceptions are those that are checked at compile-time and require explicit handling using try-catch blocks or the throws keyword. Unchecked exceptions are runtime exceptions and do not require explicit exception handling. To create a custom checked exception class, you need to extend the java.lang.Exception class, like this: ```java public class CustomCheckedException extends Exception { public CustomCheckedException(String message) { super(message); } } ``` To create a custom unchecked exception class, you need to extend the java.lang.RuntimeException class, like this: ```java public class CustomUncheckedException extends RuntimeException { public CustomUncheckedException(String message) { super(message); } } ```

Step-by-step solution

Understanding Checked and Unchecked Exceptions

In Java, there are two types of exceptions: checked and unchecked exceptions. Checked exceptions are the ones that are checked at the compile-time and need to be handled explicitly in the code using try-catch blocks or by specifying throws keyword, while unchecked exceptions are runtime exceptions, and they don't require explicit exception handling. Checked exceptions inherit from the java.lang.Exception class, and unchecked exceptions inherit from the java.lang.RuntimeException class, which in turns, inherits from the java.lang.Exception class. Now, let's create a custom exception class and demonstrate how to make it checked and unchecked.

Creating a Custom Checked Exception Class

To create a custom checked exception class, you need to extend the java.lang.Exception class. Here's an example: ```java public class CustomCheckedException extends Exception { public CustomCheckedException(String message) { super(message); } } ``` In this example, we have created a custom checked exception called CustomCheckedException, which extends the java.lang.Exception class and has a constructor that accepts a message as an argument.

Creating a Custom Unchecked Exception Class

To create a custom unchecked exception class, you need to extend the java.lang.RuntimeException class. Here's an example: ```java public class CustomUncheckedException extends RuntimeException { public CustomUncheckedException(String message) { super(message); } } ``` In this example, we have created a custom unchecked exception called CustomUncheckedException, which extends the java.lang.RuntimeException class and has a constructor that accepts a message as an argument. In conclusion, to create a custom exception and make it checked or unchecked, you need to extend the appropriate class. Extend the java.lang.Exception class for checked exceptions and java.lang.RuntimeException class for unchecked exceptions.