• Defining multiple methods with same name and same signature in super class and sub class known as method overriding.
• When Overriding a method there is a chance of having statements which may cause exceptions so we need to handle those inside method.
• Otherwise simply we can give responsibility of handling exceptions to calling method.
• We can give the responsibility of handling exceptions of a method to calling place by using throws keyword in java.
• Now we are going to discuss about exception handling in method overriding in java.
• When am method is overridden in sub class and super class method having throws exception. Then we have some scenarios to discuss.

• When super class method not throws ant exception,
• We can add throws unchecked exception in sub class overridden method.
• We can not add throws checked exception.

• If super class method throws checked exceptions sub class overridden method can throw same exception , sub class exception or no exception but can not declare parent exception.
• If super class method throws unchecked exceptions then no rules.
  

• Exceptions are the objects representing the logical errors that occur at run time and makes JVM enters into the state of  "ambiguity".
• The objects which are automatically created by the JVM for representing these run time errors are known as Exceptions

• An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch. Most such errors are abnormal conditions.
• Difference between exception and error

• Exceptions can  be handled using try catch blocks.
• The statements which are proven to generate exceptions need to keep in try block so that whenever is there any exception identified in try block that will be assigned to corresponding exception class object in catch block
• More information about try catch finally

• Throwable.

• java.lang.Exception

• Throw keyword is used to throw exception manually.
• Whenever it is required to suspend the execution of the functionality based on the user defined logical error condition we will use this throw keyword to throw exception.
• Throw keyword in java

• It is possible to have try block without catch block by using finally block
• Java supports try with finally block
• As we know finally block will always executes even there is an exception occurred in try block, Except System.exit() it will executes always.
• Is it possible to write try block without catch block

• Yes we can write multiple catch blocks under single try block.
• Multiple catch blocks in java

• The block of statements to which the control would never reach under any case can be called as unreachable blocks.
• Unreachable blocks are not supported by java.
• Unreachable blocks in java

• By extending Exception class we can define custom exceptions.
• We need to write a constructor for passing message .
• User defined exception in java

• In Java there are three ways to find the details of the exception .
• They are 

1. Using an object of java.lang.Exception
2. Using public void printStackTrace() method
3. Using public String getMessage() method.

• 3 different ways to print exception message in java

• Finally vs final vs finalize

• Yes we can write return statement of the method in try block and catch block
• We need to follow some rules to use it.Please check below link
• Return statement in try and catch blocks

• Yes we can write return statement of the method in finally block
• We need to follow some rules to use it.Please check below link
• Return statement in finally block

•  throw keyword used to throw user defined exceptions.(we can throw predefined exception too)
• Using throws keyword we can explicitly provide the information about unhand-led exceptions of the method to the end user, Java compiler, JVM.
• Throw vs throws

•  No. As mentioned above already
• If super class method throws exceptions in sub class if you want to mention throws  then use  same class  or its  sub class exception.
• So we can not change from unchecked to checked 

•  If sub class throws checked exception super class should throw same or super class exception of this.
• If super class method  throws checked or unchecked exceptions its not mandatory to put throws in sub class overridden method.
• If super class method throws exceptions in sub class if you want to mention throws  then use  same class  or its  sub class exception.

•  Compile time error will come.

• It is not possible prior to java 7.
• new feature added in java 7.

• One more interesting feature of Java 7 is try with resource 
• In Java, if you use a resource like input or output streams or any database connection logic you always need to close it after using. 
• It also can throw exceptions so it has to be in a try block and catch block. The closing logic  should be in finally block. This is a least the way until Java 7. This has several disadvantages:
  
  
  1.     You'd have to check if your ressource is null before closing it
  2.     The closing itself can throw exceptions so your finally had to contain another try -catch
  3.     Programmers tend to forget to close their resources

• The solution given by using try with resource statement.

• Top 20 Java Exception handling interview questions and answers for freshers and experienced

• In Java there are three ways to find the details of the exception .
• They are 

1. Using an object of java.lang.Exception
2. Using public void printStackTrace() method
3. Using public String getMessage() method.

•  An object of Exception class prints the name of the exception and nature of the exception.

• This is the method which is defined in java.lang.Throwable class and it is inherited into java.lang.Error class and java.lang.Exception class
• This method will display the name of the exception and nature of the message and line number where exception has occurred.

•  This is also a method which is defined in java.lang.Throwable class and it is inherited in to both java.lanf.Error and java.lang.Exception classes.
• This method will display the only exception message

• Throw keyword is used to throw exception manually.
• Whenever it is required to suspend the execution of the functionality based on the user defined logical error condition we will use this throw keyword to throw exception.
• So we need to handle these exceptions also using try catch blocks.

• throw keyword must follow Throwable type of object.
• It must be used only in method logic.
• Since it is a transfer statement , we can not place statements after throw statement. It leads to compile time error Unreachable code

•  We can throw user defined exception using throw keyword.

1. //Custom exception
2. package com.instanceofjavaforus;
3. public class InvalidAgeException extends Exception {
4.  InvaidAgeException(String msg){
5.  super(msg);
6.  }
7. }
    

1. package com.exceptions;
2. public class ThrowDemo {
3. 
   
4. public boolean isValidForVote(int age){
5.  
6.  try{
7.    if(age<18){
8.   throw new InvalidAgeException ("Invalid age for voting");
9. }
10.  }catch(Exception e){
11.  System.out.println(e);
12.  }
13.   return false;
14.  }
15.  
16. public static void main(String agrs[]){
17.  
18.  ThrowDemo obj= new ThrowDemo();
19.    obj.isValidForVote(17);
20.  
21.   }
22. }

• Lets see a java example programs which can raise multiple exceptions.

•  Lets see second case:

• In the 1st program there is a chance of getting two types of exceptions and we kept only one catch block with  ArithmeticException e . 
• But there will be chance of getting ArrayIndexOutOfBoundsException too. 
• So we need to keep multiple catch blocks in order to handle all those exceptions
• Or else we can keep single catch block with super class Exception class object.

Multiple catch blocks for single try block:

• One try can have multiple catch blocks 
• Every try should and must be associated with at least one catch block.( try without catch)
• Whenever an exception object is identified in try block and if there are multiple catch blocks then the priority for the catch block would be given based on order in which catch blocks are have been defined.
• Highest priority would be always given to first catch block . If the first catch block can not handle the identified exception object then it considers the immediate next catch block.

•  We have to know the names of every corresponding exception class names.
• We have to understand which statement is generating which exception class object.

•  Define a single catch block so that it should be able to handle any kind of exceptions identified in the try block.
• Exception class is the super class for all the exception classes.
• To the reference of super class object we can assign any sub class object.