Exception Handling in Java-Part 2

The error that occurs during execution which leads to disturb in flow of execution is nothing but the exception .Exceptions can be of any type and the ways to handle that exception are called as exception handling.

Checked and unchecked are the types of exceptions in java.

Checked exceptions: a program has to catch and handle that exception is called a checked exception .In the source code only checked exceptions have to be declared.Checked exceptions are declared by the compiler at compile time.

Unchecked exception: unchecked exceptions are not checked by the compiler. in the program unchecked exceptions are not specified and it does not cause compilation error. The unchecked exception handled at run time

some of the exceptions in java are as follows.

NullPointerException:

If we are using any pointer to referring to the member but that member is of null object then this exception thrown as Null means nothing it means it represents nothing.NullPointerException it is an unchecked exception.

ex-

class NullPointer_code

{

public static void main(String args[])

{

try {

String a = null; System.out.println(a.charAt(0));

} catch(NullPointerException e) { System.out.println("NullPointerException thrown..");

}

}

}

Output: NullPointerException thrown..

NumberFormatException:

Suppose we have created one class in which we are assigning a string value to integer data type and if that method is not able to convert that string into numeric format then This exception is raised.NumberFormatException it is an unchecked exception.

class NumberFormat_code

{

public static void main(String args[])

{

try {

int num = Integer.parseInt ("abcd") System.out.println(num);

} catch(NumberFormatException e) { System.out.println("Number format exception thrown");

}

}

}

Output: Number format exception thrown

RuntimeException:

When any exception occurs during runtime then it is represented by RuntimeException This represents any exception which occurs during runtime.RuntimeException it is an unchecked exception.

ex-

public class MyExceptionTest { public void testRuntimeException () { throw new MyException();

}

 public static void main(String[] args) { try {

new MyExceptionTest().testRuntimeException();

 } catch(Exception e) { System.out.println(e.getClass().getName());

}

}

}

class MyException extends RuntimeException { public MyException() {

super();

}

}

Output: MyException

StringIndexOutOfBoundsException:

It is thrown from String class methods to show an index is either negative than the size of the string.StringIndexOutOfBoundsException it is an unchecked exception.And it extends a Run time exception.

NoSuchFieldException:

Suppose if our class does not contain a field or variable and we are trying to call that then it is thrown that exception.

NoSuchMethodException:

The exception is thrown when we access a method which is not found. It means suppose we try to dynamically use a method on a class, and the method does not actually exist then also it gives NoSuchMethodException.NoSuchMethodException it is a checked exception.

Amarja Chede

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