# Sec 3: Exception Handling

## 73) What is Exception Handling?

Exception Handling is a mechanism to **handle runtime errors**.It is mainly used to handle checked exceptions.

## 74) What is difference between Checked Exception and Unchecked Exception?

**1) Checked Exception**\
The classes that **extend Throwable** class except RuntimeException and Error are known as checked exceptions e.g.IOException,SQLException etc. Checked exceptions are checked at compile-time.\
**2) Unchecked Exception**\
The classes that **extend RuntimeException** are known as unchecked exceptions e.g. ArithmeticException,NullPointerException etc. Unchecked exceptions are not checked at compile-time.

## 75) What is the base class for Error and Exception?

Throwable.

## 76) Is it necessary that each try block must be followed by a catch block?

It is **not necessary** that each try block must be followed by a catch block. It should be followed by either a **catch block** OR a **finally block**. And whatever exceptions are likely to be thrown should be declared in the throws clause of the method.

## 77) What is finally block?

finally block is a block that is always executed.

## 78) Can finally block be used without catch?

Yes, by try block. finally must be followed by either try or catch.

## 79) Is there any case when finally will not be executed?

finally block will not be executed if program exits(either by calling System.exit() or by causing a fatal error that causes the process to abort).

## 80) What is difference between throw and throws?

![](/files/-LpvA0-vgwl7FCuh_-xm)

## 81) Can an exception be rethrown?

Yes.

## 82) Can subclass overriding method declare an exception if parent class method doesn't throw an exception ?

Yes but only unchecked exception not checked.

## 83) What is exception propagation ?

Forwarding the exception object to the invoking method is known as exception propagation.


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