Expections

An exception is an event, which occurs during the execution of a program, that disrupts the
normal flow of the program’s instructions. When error occurs, an exception object is created and given to the runtime system, this is called throw an exception. The runtime system searches the call stack for a method that contains a block of code that can
handle the exception.
The exception handler chosen is said to catch the exception

Types of Expections

• Checked Expection
  (IOException, SQLException, etc.)
• runtime Expection
  (ArraylndexOutOfBoundsExceptions, ArithmeticException, etc.)
• Error
  (VirtualMachineError, OutOfMemoryError, etc.)

Uncheck exceptions VS Checked exceptions

All classes that are subclasses of RuntimeException (typically caused by defects in your program’s code) or Error (typically ‘system’ issues) are unchecked exceptions.

All classes that inherit from class Exception but not directly or indirectly from class.
RuntimeException are considered to be checked exceptions.

User-defined Exception

A checked exception need to extend the Exception class, but not directly or indirectly from class RuntimeException.

An unchecked exception (like a runtime exception) need to extend the RuntimeException class.
Normally we define a checked exception, by extending the Exception class. Like in the following code

class MyExpection extends Exception {
    public MyExpection(String message){
        super(message).
    }
}

Java Expections