About Exceptions

What is Exception Handling

Exception Handling is a mechanism to handle runtime errors such as ClassNotFoundException, IOException, SQLException, RemoteException, etc.

1. statement 1;  
2. statement 2;  
3. statement 3;  
4. statement 4;  
5. statement 5;//exception occurs  
6. statement 6;  
7. statement 7;  
8. statement 8;  
9. statement 9;  
10. statement 10;

Suppose there are 10 statements in your program and there occurs an exception at statement 5, the rest of the code will not be executed i.e. statement 6 to 10 will not be executed. 

If we perform exception handling, the rest of the statement will be executed. 

That is why we use exception handling in Java.

Common Scenarios of Java Exceptions

There are given some scenarios where unchecked exceptions may occur. They are as follows:

1) A scenario where ArithmeticException occurs

If we divide any number by zero, there occurs an ArithmeticException.

1. int a=50/0;//ArithmeticException  

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2) A scenario where NullPointerException occurs

If we have a null value in any variable, performing any operation on the variable throws a NullPointerException.

1. String s=null;  
2. System.out.println(s.length());//NullPointerException  

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3) A scenario where NumberFormatException occurs

The wrong formatting of any value may occur NumberFormatException. Suppose I have a string variable that has characters, converting this variable into digit will occur NumberFormatException.

1. String s="abc";  
2. int i=Integer.parseInt(s);//NumberFormatException  

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4) A scenario where ArrayIndexOutOfBoundsException occurs

If you are inserting any value in the wrong index, it would result in ArrayIndexOutOfBoundsException as shown below:

1. int a[]=new int[5];  
2. a[10]=50; //ArrayIndexOutOfBoundsException