Exceptions in JAVA

Exceptions:-

An exception is a problem that arises during the execution of a program. An exception can occur for many different reasons.

Exceptions divided into 3 categories:-

1.        Checked Exceptions (Compile time Exception):-

These are Exceptions occurs when the program has wrong syntax or the grammar of the language. These exceptions can be identifying during compilation time. Compiler identifies the checked exceptions. Desk checking mechanism is the solution of compile time errors (checked exceptions).

2.       Unchecked Exception (Runtime Exceptions):-

These Exceptions are detected by JVM at the time of running the program. “Exception handling” mechanism is solving these types of exceptions.

3.       Errors:-

These errors represent bad logic. These errors are not detected by the compiler or JVM. Logical errors are detected by comparing the program output with manually calculated result.

Ø  An exception is an error that can be handled. When there is an exception JVM displays exception name & its description.

Ø  An error cannot be handled.

Exception Handling Mechanism:-

1.       Try block.

2.       Catch block.

3.       Finally block.

4.       Throws.

5.       Throw.

If we have exception doubt in the program that can implement in try block.

If exception is available it will throws corresponding catch block.

There is an exception catch and finally block is executed.

An exception is not available catch will not execute and finally block is execute.

Finally block has closing connection.

We can use more than one catch block.

Example:-

try{

Statement; // implement code

}

catch(Exception exobj)   //exobj is object of an exception,  it has exception details.

{

out.println(exobj);  //it display exception details

}

catch(Exception ex)

        {

            out.println(ex);  //it display exception details

        }

finally {           

            out.close();   //close connection

        }

Example Program:-

public class Exceptionss {

    public static void main(String a[]){

        int d=5,b=10,c;

        try{

            c=d/b;

            if(d<10)

            {

                MyException me=new MyException("error");

                throw me;

            }

        }

    catch(ArithmeticException ae)

    {

        ae.printStackTrace();

    }

    catch(MyException me)

    {

        System.out.println(me);

    }

    }

}

class MyException extends Exception

{

    String msg;

    MyException()

    {

    }

MyException(String msg)

{

    super(msg);

    this.msg=msg;

  }

}