How to create custom exceptions in Java - CodeJava.net.
The exception class here is the NumberRangeException class. You must have noticed that this class is derived from the exception class. A variable 'msg' of String type is defined and in the constructor it is initialized with appropriate message. You are also overriding the function toString with statement 'System.out.println (e);' so that the caught exception object can convey some message when.
The Java Exception class describes the kind of event, and the message provides detailed information about it. You can take this concept one step further by using a custom exception.
The Creating Exception Classes section in this chapter explains how to create your own exception classes. For now, all you need to remember is that you can throw only objects that inherit from the java.lang.Throwable class. Note that the declaration of the pop method does not contain a throws clause.
In this example we have explained you to create own exception class and then use in the program. The Exception class defined by developer is called Custom or User Defined Exception. To define a custom exception class you have to extend the class with Exception class. Lets start developing our custom exception class. In Java API all exception.
Creating Your Own Exception Classes When faced with choosing the type of exception to throw, you can either use one written by someone else—the Java platform provides a lot of exception classes that you can use—or you can write one of your own. You should write your own exception classes if you answer yes to any of the following questions.
Steps to Write User Defined Exception: Write your exception class by extending java.lang.Exception or java.lang.RuntimeException. Declare some instance variable inside exception class. Write default constructor inside the exception class. Write one parameterized constructor if required.
In java we can create our own exception class and throw that exception using throw keyword. These exceptions are known as user-defined or custom exceptions. In this tutorial we will see how to create your own custom exception and throw it on a particular condition.