Java Exception Handling examples
11:04:00
Here we have
shared examples of few most frequently seen exceptions in java. These examples
will help you understand Exception
handling in Java.
Example 1: Arithmetic exception
Class:
This is a built-in-class present in java.lang package. This exception occurs when an integer is divided by zero.
Java.lang.ArithmeticExceptionThis is a built-in-class present in java.lang package. This exception occurs when an integer is divided by zero.
class ExceptionDemo1
{
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 of above program:
Arithmetic Exception: You can't divide an integer by 0
Explanation: In the above example I’ve divided an
integer by a zero and due to which
ArithmeticException is thrown.
Example 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 ExceptionDemo2
{
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.
Example 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
For E.g. The statement
int num=Integer.parseInt ("XYZ") ; would throw NumberFormatException because String “XYZ” cannot be parsed to int.
Complete Code:
class ExceptionDemo3
{
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
Example 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.
E.g.
class ExceptionDemo4
{
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.
Example 5: NullPointer Exception
Class:
An object of this class gets created whenever a member is invoked with a “null” object.
Example:
Java.lang.NullPointer ExceptionAn object of this class gets created whenever a member is invoked with a “null” object.
Example:
package beginnersbook.com;
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.
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