How to create a custom exception in Java?
Custom Checked and Custom Unchecked 1 Example: Custom Checked Exception. The following Java program demonstrates how to create a custom checked exception. 2 Exception at compile time. When compiling, the above program generates the following exception. 3 Example: custom unchecked exception. 4 runtime exception
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What makes an exception a checked exception in Java?
Throwable, Exception, and any exception derived from Exception other than those derived from RuntimeException count as checked exceptions: they are the ones you must declare to throw or catch if you call something that throws them. Altogether, Java’s exception hierarchy is a bit complicated…
Is RuntimeException an exception in Java?
The error and its subclasses are unchecked exceptions, which means that your code does not have to catch an Error that might be thrown, nor does it have to declare that it throws those Errors. RunTimeException and its subclasses are also unchecked exceptions, despite their placement in the class hierarchy.
Do you need to extend exception class in Java?
All exceptions must be a child of Throwable. If you want to write a checked exception that is applied automatically by the Handle or Declare rule, you must extend the exception class. If you want to write a runtime exception, you must extend the RuntimeException class.
2. Follow the naming convention When you take a look at the exception classes provided by the JDK, you quickly recognize that all of their names end with “Exception”. This general naming convention is used throughout the Java ecosystem. And your custom exception should also follow it. 3. Provide Javadoc comments for your exception class
What are the best practices for custom exceptions?
There are 4 general best practices to follow when deciding to implement a custom exception class. These recommendations make your code and API easier to understand. They also reduce the amount of documentation required.
What is the difference between a custom exception and a checked exception?
The implementation of a custom unchecked exception is almost identical to a checked exception. You must follow the same recommendations that I explained at the beginning of this post. The only difference is that an unchecked exception has to extend RuntimeException instead of Exception.
What should the class name of an exception end with?
The class name of your exception must end with Exception. If an API method specifies an exception, the exception class becomes part of the API and you must document it. You must provide a constructor that sets the cause of the exception.