Skip to main content

Java Exception Handling Examples

Java Execption handling Example


1: Arithmetic exception

Class: Java.lang.ArithmeticException
This is a built-in-class present in java.lang package. This exception occurs when an integer is divided by zero.
class ExceptionDemo
{
   public static void main(String args[])
   {
      try{
         int num1=30, num2=0;
         int output=num1/num2;
         System.out.println ("Result = " + output);
      }
      catch(ArithmeticException e){
         System.out.println ("Arithmetic Exception: You can't divide an integer by 0");
      }
   }
}
Output :
Arithmetic Exception: You can't divide an integer by 0
In the above example I’ve divided an integer by a zero and due to which ArithmeticException is thrown.

2: ArrayIndexOutOfBounds Exception

Class: Java.lang.ArrayIndexOutOfBoundsException
This is a built in class present in java.lang package. This exception occurs when the referenced element does not exist in the array. For e.g. If array is having only 5 elements and we are trying to display 7th element then it would throw this exception.
Example:
class ExceptionDemo1
{
   public static void main(String args[])
   {
      try{
        int a[]=new int[10];
        //Array has only 10 elements
        a[11] = 9;
      }
      catch(ArrayIndexOutOfBoundsException e){
         System.out.println ("ArrayIndexOutOfBounds");
      }
   }
}
Output:
ArrayIndexOutOfBounds
In the above example the array is initialized to store only 10 elements indexes 0 to 9. Since we are invoking index 11 that’s why it is throwing this exception.

3: NumberFormat Exception

Class: Java.lang.NumberFormatException
The object of the above built-in class gets created whenever a string is parsed to any numeric variable.
For E.g. The statement int num=Integer.parseInt ("XYZ") ; would throw NumberFormatException because String “XYZ” cannot be parsed to int.
Complete Code:
class ExceptionDemo2
{
   public static void main(String args[])
   {
      try{
          int num=Integer.parseInt ("XYZ") ;
          System.out.println(num);
      }catch(NumberFormatException e){
          System.out.println("Number format exception occurred");
       }
   }
}
Output:
Number format exception occurred

4: StringIndexOutOfBound Exception

Class: Java.lang.StringIndexOutOfBoundsException
  • An object of this class gets created whenever an index is invoked of a string, which is not in the range.
  • Each character of a string object is stored in a particular index starting from 0.
  • To get a character present in a particular index of a string we can use a method charAt(int) of java.lang.String where int argument is the index.
class ExceptionDemo3
{
   public static void main(String args[])
   {
      try{
          String str="easysteps2buildwebsite";
          System.out.println(str.length());;
          char c = str.charAt(0);
          c = str.charAt(40);
          System.out.println(c);
      }catch(StringIndexOutOfBoundsException e){
          System.out.println("StringIndexOutOfBoundsException!!");
       }
   }
}
Output:
22
StringIndexOutOfBoundsException!!
Exception occurred because the referenced index was not present in the String.

5: NullPointer Exception

Class: Java.lang.NullPointer Exception
An object of this class gets created whenever a member is invoked with a “null” object.
Example:

class Exception2
{
public static void main(String args[])
{
 try{
  String str=null;
  System.out.println (str.length());
 }catch(NullPointerException e){
  System.out.println("NullPointerException..");
 }
}
}
Output:
NullPointerException..
Here, length() is the function, which should be used on an object. However in the above example String object str is null so it is not an object due to which NullPointerException occurred.
Labels:

Comments

Post a Comment

Popular posts from this blog

Switch Case

Syntax : Switch Case in Java Programming It is alternative to else-if ladder. Switch Case Syntax is similar to – C/C++  Switch. Switch allows you to choose a block of statements to run from a selection of code, based on the return value of an expression. The expression used in the switch statement must return an  int, a String, or an enumerated value . switch (selection) { // value case value1 : // checking value 1 statement ( s ) ; break ; // use to break switch flow if condition match case value2 : // checking value 2 statement ( s ) ; break ; . . case value_n : statement ( s ) ; break ; default : statement ( s ) ; } Different Ways of Using Switch Case : Switch Case Using Integer Case int i=3; switch (i) { case 1 : System . out . println ( "One player is playing this game." ) ; break ; case 2 : System . out . println ( "Two players are playing ...
6 comments
Read more

Inheritance in Java

Inheritance in Java Inheritance  is one of the feature of Object-Oriented Programming (OOPs). Inheritance allows a class to use the properties and methods of another class. In other words, the derived class inherits the states and behaviors from the base class. The derived class is also called subclass and the base class is also known as super-class . The derived class can add its own additional variables and methods. These additional variable and methods differentiates the derived class from the base class. Inheritance is a  compile-time  mechanism. A super-class can have any number of subclasses . But a subclass can have only one superclass. This is because Java does not support multiple inheritance. The superclass and subclass have  “is-a”  relationship between them. Let’s have a look at the example below. Inheritance  Example Let’s consider a superclass  Vehicle . Different vehicles have different features and properties howeve...
15 comments
Read more

Multilevel inheritance

Multilevel inheritance We discussed a bit about  Multilevel inheritance  in types of inheritance in java. In this tutorial we will explain multilevel inheritance with the help of   diagram  and  example program . It’s pretty clear with the diagram that in Multilevel inheritance there is a concept of grand parent class. If we take the example of above diagram then class C inherits class B and class B inherits class A which means B is a parent class of C and A is a parent class of B. So in this case class C is implicitly inheriting the properties and method of class A along with B that’s what is called multilevel inheritance. Example : In this example we have three classes –  Car, Maruti and Maruti800. We have done a setup – class Maruti extends Car and class Maurit800 extends Maurti. With the help of this Multilevel hierarchy setup our Maurti800 class is able to use the methods of both the classes (Car and Maruti). class Car { ...
13 comments
Read more