Exception Handling in Java

1
2
3
Dictionary Meaning:
 Exception is an abnormal condition.
Exception Handling is a mechanism to handle runtime errors such as
ClassNotFound, IO, SQL, Remote etc.
Advantage of Exception Handling
The core advantage of exception handling is 
to maintain the normal
flow of the application
.
Exception normally disrupts the normal flow of the application that is
why we use exception handling. Let's take a scenario:
4
Cont…
statement 1;
statement 2;
statement 3;
statement 4;
statement 5;//exception occurs
statement 6;
statement 7;
statement 8;
statement 9;
statement 10;
Suppose there is 10 statements in your program and there occurs an exception at
statement 5, rest of the code will not be executed i.e. statement 6 to 10 will not run. If
we perform exception handling, rest of the statement will be executed. That is why we
use exception handling in java.
5
6
There are mainly two types of exceptions: checked and
unchecked where error is considered as unchecked exception.
 The sun microsystem says there are three types of exceptions:
1.
Checked Exception
2.
Unchecked Exception
3.
Error
7
1) Checked Exception
The classes that extend Throwable class except RuntimeException and Error are
known as checked exceptions e.g.IOException, SQLException etc. Checked
exceptions are checked at compile-time.
2) Unchecked Exception
The classes that extend RuntimeException are known as unchecked exceptions e.g.
ArithmeticException, NullPointerException, ArrayIndexOutOfBoundsException
etc. Unchecked exceptions are not checked at compile-time rather they are checked
at runtime.
3) Error
Error is irrecoverable e.g. OutOfMemoryError, VirtualMachineError,
AssertionError etc.
8
1) Scenario where ArithmeticException occurs
    
If we divide any number by zero, there occurs an ArithmeticException.
int
 a=
50
/
0
;
//ArithmeticException
2) Scenario where NullPointerException occurs
      If we have null value in any variable, performing any operation by the variable
occurs an NullPointerException
String s=
null
;
System.out.println(s.length());
//NullPointerException
9
4) Scenario where ArrayIndexOutOfBoundsException occurs
   If you are inserting any value in the wrong index, it would result ArrayIndexOutOfBoundsException
as shown below:
int
 a[]=
new
 
int
[
5
];
a[
10
]=
50
; 
//ArrayIndexOutOfBoundsException
3) Scenario where NumberFormatException occurs
The wrong formatting of any value, may occur NumberFormatException. Suppose I have a string variable that
have characters, converting this variable into digit will occur NumberFormatException
String s=
"abc"
;
int
 i=Integer.parseInt(s);
//NumberFormatException
10
There are 5 keywords used in java exception handling.
1.
try
2.
catch
3.
finally
4.
throw
5.
throws
11
Java try block
Java try block is used to enclose the code that might throw an exception. It must be
used within the method.
Java try block must be followed by either catch or finally block.
Syntax of java try-catch
try
{
     //code that may throw exception
}
catch
(Exception_class_Name ref){}
Syntax of try-finally block
try
{
    //code that may throw exception
}
finally
{}
12
Java catch block is used to handle the Exception. It must be used
after the try block only.
You can use multiple catch block with a single try.
public class TestMultipleCatchBlock{
  public static void main(String args[]){
   try{
         int a[]=new int[5];
         a[5]=30/0;
   }
   catch(ArithmeticException e){System.out.println("task1 is completed");}
   catch(ArrayIndexOutOfBoundsException e){System.out.println("task 2 completed");}
   catch(Exception e){System.out.println("common task completed");}
   System.out.println("rest of the code...");
 }
}
13
Java finally block
 is a block that is used 
to execute important code
 such as
closing connection, stream etc.
Java finally block is always executed whether exception is handled or not.
Java finally block must be followed by try or catch block.
class TestFinallyBlock
{
  public static void main(String args[]){
  try{
   int data=25/5;
   System.out.println(data);
  }
  catch(NullPointerException e){System.out.println(e);}
  finally{System.out.println("finally block is always executed");}
  System.out.println("rest of the code...");
  }
}
14
Case 1
Let's see the java finally example where 
exception doesn't occur
.
class TestFinallyBlock
{
  public static void main(String args[])
  {
     try{
            int data=25/5;
            System.out.println(data);
     }
     catch(NullPointerException e){System.out.println(e);}
     finally{System.out.println("finally block is always executed");}
     System.out.println("rest of the code...");
  }
}
Output:
       finally block is always executed
       rest of the code...
15
Case 2
Let's see the java finally example where 
exception occurs and not handled
.
class TestFinallyBlock1
{
  public static void main(String args[])
  {
     try{
        int data=25/0;
        System.out.println(data);
     }
     catch(NullPointerException e){System.out.println(e);}
     finally{System.out.println("finally block is always executed");}
     System.out.println("rest of the code...");
  }
}
Output: finally block is always executed
             Exception in thread main java.lang.ArithmeticException:/ by zero
16
Case 3
Let's see the java finally example where 
exception occurs and handled
public class TestFinallyBlock2
{
  public static void main(String args[])
  {
      try{
         int data=25/0;
         System.out.println(data);
      }
      catch(ArithmeticException e){System.out.println(e);}
      finally{System.out.println("finally block is always executed");}
      System.out.println("rest of the code...");
  }
}
Output: Exception in thread main java.lang.ArithmeticException:/ by zero
             finally block is always executed
             rest of the code...
17
The Java throw keyword is used to explicitly throw an exception.
We can throw either checked or uncheked exception in java by throw keyword.
The throw keyword is mainly used to throw custom exception. We will see
custom exceptions later.
The syntax of java throw keyword:
throw
 exception;
java throw keyword example
public class TestThrow1
{
   static void validate(int age)
   {
     if(age<18)
      throw new ArithmeticException("not valid");
     else
      System.out.println("welcome to vote");
   }
   public static void main(String args[])
   {
      validate(13);
      System.out.println("rest of the code...");
  }
}
O
u
t
p
u
t
:
 
E
x
c
e
p
t
i
o
n
 
i
n
 
t
h
r
e
a
d
 
m
a
i
n
 
j
a
v
a
.
l
a
n
g
.
A
r
i
t
h
m
e
t
i
c
E
x
c
e
p
t
i
o
n
:
n
o
t
 
v
a
l
i
d
18
T
h
e
 
J
a
v
a
 
t
h
r
o
w
s
 
k
e
y
w
o
r
d
 
i
s
 
u
s
e
d
 
t
o
 
d
e
c
l
a
r
e
 
a
n
 
e
x
c
e
p
t
i
o
n
.
 
I
t
 
g
i
v
e
s
 
a
n
i
n
f
o
r
m
a
t
i
o
n
 
t
o
 
t
h
e
 
p
r
o
g
r
a
m
m
e
r
 
t
h
a
t
 
t
h
e
r
e
 
m
a
y
 
o
c
c
u
r
 
a
n
 
e
x
c
e
p
t
i
o
n
 
s
o
 
i
t
 
i
s
b
e
t
t
e
r
 
f
o
r
 
t
h
e
 
p
r
o
g
r
a
m
m
e
r
 
t
o
 
p
r
o
v
i
d
e
 
t
h
e
 
e
x
c
e
p
t
i
o
n
 
h
a
n
d
l
i
n
g
 
c
o
d
e
 
s
o
 
t
h
a
t
n
o
r
m
a
l
 
f
l
o
w
 
c
a
n
 
b
e
 
m
a
i
n
t
a
i
n
e
d
.
Exception Handling is mainly used to handle the checked exceptions. If
there occurs any unchecked exception such as NullPointerException, it is
programmers fault that he is not performing check up before the code
being used.
Syntax of java throws
return_type method_name() throws exception_class_name
{
   //method code
}
19
import java.io.IOException;
class Testthrows1
{
  void m()throws IOException
  {
    throw new IOException("device error");//checked exception
  }
  void n()throws IOException
  {
     m();
  }
  void p()
  {
   try{
      n();
   }catch(Exception e){System.out.println("exception handled");}
  }
  public static void main(String args[])
  {
   Testthrows1 obj=new Testthrows1();
   obj.p();
   System.out.println("normal flow...");
  }
}
Output:
exception handled
normal flow...
20
Java provides most of the errors but most of the times standard
exception cannot handles most of the exceptions.
Such exceptions are designed by the user itself.
For example if we put date 30 to month February then we have error
InvalidDateException, but not such kind of exception.
A user defined exception class must extend Exception. General form is
given below;
class UserDefinedException extends Exception
{
     // code
}
21
1.
Write a Java program to find the exception Marks Out
of Bounds. Create a class student If the mark is greater
than 100, it must generate the user defined exception
called Mark Out of Bounds exception and throw it.
2.
Write a Java program to find out maximum of array
elements and check for array limit. (Use exception
handling)
22
class MarksOutOfBoundsException extends Exception
{
   public MarksOutOfBoundsException(String str)
   {
      super(str);
   }
}
class student
{
    int marks;
    public student()
    {
       marks=0;
    }
    public student(int marks)
    {
       this.marks=marks;
    }
    public void checkMarks() throws MarksOutOfBoundsException
    {
         if(marks>100)
         {
            throw new MarksOutOfBoundsException("Invalid Marks");
         }
         else
         {
            System.out.println("Marks: "+marks);
         }
    }
}
public class throwsDemo {
    public static void main(String args[]) throws MarksOutOfBoundsException
    {
       student s=new student(101);
       s.checkMarks();
    }
}
Program 1 solution
23
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class myEceptionDemo {
   public static void main(String args[])
   {
      int a[]=new int[5];
      int max=0;
      BufferedReader b=new BufferedReader(new InputStreamReader(System.in));
      try
      {
         System.out.println("enter the element");
         for(int i=0;i<a.length;i++)
         {
            a[i]=Integer.parseInt(b.readLine());
         }
         for(int i=0;i<5;i++)
         {
            if(a[i]>max)
            {
              max=a[i];
            }
         }
         System.out.println("maximum number is: "+max);
      }
      catch(ArrayIndexOutOfBoundsException exp)
      {
         System.out.println("Out of the array limit...");
      }
      catch(IOException e)
      {
      }
   }
}
Program 2 solution

								

								

								

										

												
Slide Note

												

										

								


								
						

							
						


							

								

									
										
Embed
									
									
										
Share
									

									
									
									

								

								
							


							

							 
 							 
 							 
						  


							
							

								
Exception handling in Java is a crucial mechanism to manage runtime errors effectively. This article explains the concept of exceptions, advantages of using exception handling, types of exceptions (checked, unchecked, and errors), common scenarios like ArithmeticException and NullPointerException, and the role of exception handling in maintaining the normal flow of an application. By handling exceptions, you can ensure the continued execution of code even when errors occur, improving the reliability and robustness of your Java programs.


								
    
																		
  •   Java
    • 
																	
  •    Exception Handling
    • 
																	
  •    Checked Exceptions
    • 
																	
  •    Unchecked Exceptions
    • 
																	
  •    Error Handling
    • 
																

								

								

									

										ityu
										

											 ityu Follow
											

										

									

									
Uploaded on Nov 23, 2024 | 0 Views

								

								


								

									
Download Presentation

									
								

								
Please find below an Image/Link to download the presentation.

								
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.
									Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.


									
									

									


										 
										 
										 
										 

									

									

									

									

										
 E N D 

									


								
Presentation Transcript

								

								
  1. 1
    2. 
            
            
            
  2. 2
    3. 
            
            
            
  3.  Dictionary Meaning: Exception is an abnormal condition.     Exception Handling is a mechanism to handle runtime errors such as  ClassNotFound, IO, SQL, Remote etc. Advantage     The core advantage of exception handling is to maintain the normal  flow of the application.      Exception normally disrupts the normal flow of the application that is  why we use exception handling. Let's take a scenario: Advantage  of of  Exception Exception  Handling Handling 3
    4. 
            
            
            
  4. Cont statement 1;   statement 2;   statement 3;   statement 4;   statement 5;//exception occurs   statement 6;   statement 7;   statement 8;   statement 9;   statement 10; Suppose there is 10 statements in your program and there occurs an exception at  statement 5, rest of the code will not be executed i.e. statement 6 to 10 will not run. If  we perform exception handling, rest of the statement will be executed. That is why we  use exception handling in java. 4
    5. 
            
            
            
  5. 5
    6. 
            
            
            
  6.  There are mainly two types of exceptions: checked and  unchecked where error is considered as unchecked exception.      The sun microsystem says there are three types of exceptions: Checked Exception Unchecked Exception Error 1. 2. 3. 6
    7. 
            
            
            
  7. 1) Checked Exception The classes that extend Throwable class except RuntimeException and Error are  known as checked exceptions e.g.IOException, SQLException etc. Checked  exceptions are checked at compile-time. 2) Unchecked Exception The classes that extend RuntimeException are known as unchecked exceptions e.g.  ArithmeticException, NullPointerException, ArrayIndexOutOfBoundsException  etc. Unchecked exceptions are not checked at compile-time rather they are checked  at runtime. 3) Error Error is irrecoverable e.g. OutOfMemoryError, VirtualMachineError,  AssertionError etc. 7
    8. 
            
            
            
  8. 1) Scenario where ArithmeticException occurs If we divide any number by zero, there occurs an ArithmeticException. int a=50/0;//ArithmeticException 2) Scenario where NullPointerException occurs       If we have null value in any variable, performing any operation by the variable  occurs an NullPointerException String s=null; System.out.println(s.length());//NullPointerException 8
    9. 
            
            
            
  9. 3) Scenario where NumberFormatException occurs The wrong formatting of any value, may occur NumberFormatException. Suppose I have a string variable that  have characters, converting this variable into digit will occur NumberFormatException String s="abc"; int i=Integer.parseInt(s);//NumberFormatException 4) Scenario where ArrayIndexOutOfBoundsException occurs    If you are inserting any value in the wrong index, it would result ArrayIndexOutOfBoundsException  as shown below: int a[]=new int[5]; a[10]=50; //ArrayIndexOutOfBoundsException 9
    10. 
            
            
            
  10. There are 5 keywords used in java exception handling. 1.try 2.catch 3.finally 4.throw 5.throws 10
    11. 
            
            
            
  11. Java try block     Java try block is used to enclose the code that might throw an exception. It must be  used within the method.     Java try block must be followed by either catch or finally block. Syntax of java try-catch try{      //code that may throw exception } catch(Exception_class_Name ref){} Syntax of try-finally block try{     //code that may throw exception }finally{} 11
    12. 
            
            
            
  12.  Java catch block is used to handle the Exception. It must be used  after the try block only.     You can use multiple catch block with a single try. public class TestMultipleCatchBlock{     public static void main(String args[]){      try{   int a[]=new int[5];   a[5]=30/0;      }      catch(ArithmeticException e){System.out.println("task1 is completed");}      catch(ArrayIndexOutOfBoundsException e){System.out.println("task 2 completed");}      catch(Exception e){System.out.println("common task completed");}      System.out.println("rest of the code...");    }   }  12
    13. 
            
            
            
  13. Java finally block is a block that is used to execute important code such as  closing connection, stream etc. Java finally block is always executed whether exception is handled or not. Java finally block must be followed by try or catch block. class TestFinallyBlock {     public static void main(String args[]){     try{      int data=25/5;      System.out.println(data);     }     catch(NullPointerException e){System.out.println(e);}     finally{System.out.println("finally block is always executed");}     System.out.println("rest of the code...");     }   }  13
    14. 
            
            
            
  14. Case 1 Let's see the java finally example where exception doesn't occur. class TestFinallyBlock {     public static void main(String args[])   {     try{   int data=25/5;   System.out.println(data);     }     catch(NullPointerException e){System.out.println(e);}     finally{System.out.println("finally block is always executed");}     System.out.println("rest of the code...");     }   } Output:        finally block is always executed        rest of the code...  14
    15. 
            
            
            
  15. Case 2 Let's see the java finally example where exception occurs and not handled. class TestFinallyBlock1 {     public static void main(String args[])   {        try{           int data=25/0;           System.out.println(data);        }        catch(NullPointerException e){System.out.println(e);}        finally{System.out.println("finally block is always executed");}        System.out.println("rest of the code...");     }   } Output: finally block is always executed Exception in thread main java.lang.ArithmeticException:/ by zero 15
    16. 
            
            
            
  16. Case 3 Let's see the java finally example where exception occurs and handled public class TestFinallyBlock2 {     public static void main(String args[])   {         try{            int data=25/0;            System.out.println(data);         }         catch(ArithmeticException e){System.out.println(e);}         finally{System.out.println("finally block is always executed");}         System.out.println("rest of the code...");     }   }  Output: Exception in thread main java.lang.ArithmeticException:/ by zero finally block is always executed rest of the code... 16
    17. 
            
            
            
  17.  The Java throw keyword is used to explicitly throw an exception.     We can throw either checked or uncheked exception in java by throw keyword.  The throw keyword is mainly used to throw custom exception. We will see  custom exceptions later.     The syntax of java throw keyword:throw exception; public class TestThrow1 {      static void validate(int age)    {        if(age<18)         throw new ArithmeticException("not valid");        else         System.out.println("welcome to vote");      }      public static void main(String args[])    {         validate(13);         System.out.println("rest of the code...");     }   } java throw keyword example Output: Exception in thread main java.lang.ArithmeticException:not valid 17
    18. 
            
            
            
  18.  The Java throws keyword is used to declare an exception. It gives an  information to the programmer that there may occur an exception so it is  better for the programmer to provide the exception handling code so that  normal flow can be maintained.     Exception Handling is mainly used to handle the checked exceptions. If  there occurs any unchecked exception such as NullPointerException, it is  programmers fault that he is not performing check up before the code  being used.     Syntax of java throws return_type method_name() throws exception_class_name {      //method code   } 18
    19. 
            
            
            
  19. import java.io.IOException;   class Testthrows1 {     void m()throws IOException   {       throw new IOException("device error");//checked exception     }     void n()throws IOException   {        m();     }     void p()   {      try{         n();      }catch(Exception e){System.out.println("exception handled");}     }     public static void main(String args[])   {      Testthrows1 obj=new Testthrows1();      obj.p();      System.out.println("normal flow...");     }   } Output: exception handled normal flow... 19
    20. 
            
            
            
  20.  Java provides most of the errors but most of the times standard  exception cannot handles most of the exceptions.     Such exceptions are designed by the user itself.     For example if we put date 30 to month February then we have error  InvalidDateException, but not such kind of exception.     A user defined exception class must extend Exception. General form is  given below; class UserDefinedException extends Exception {      // code   } 20
    21. 
            
            
            
  21. 1. Write a Java program to find the exception Marks Out  of Bounds. Create a class student If the mark is greater  than 100, it must generate the user defined exception  called Mark Out of Bounds exception and throw it. 2. Write a Java program to find out maximum of array  elements and check for array limit. (Use exception  handling) 21
    22. 
            
            
            
  22. class MarksOutOfBoundsException extends Exception {    public MarksOutOfBoundsException(String str)    {       super(str);    } } class student {     int marks;     public student()     {        marks=0;     }     public student(int marks)     {        this.marks=marks;     }     public void checkMarks() throws MarksOutOfBoundsException     {          if(marks>100)          {             throw new MarksOutOfBoundsException("Invalid Marks");          }          else          {             System.out.println("Marks: "+marks);          }     } Program 1 solution } public class throwsDemo {     public static void main(String args[]) throws MarksOutOfBoundsException     {        student s=new student(101);        s.checkMarks();     } } 22
    23. 
            
            
            
  23. import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class myEceptionDemo {    public static void main(String args[])    {       int a[]=new int[5];       int max=0;       BufferedReader b=new BufferedReader(new InputStreamReader(System.in));       try       {          System.out.println("enter the element");          for(int i=0;i<a.length;i++)          {             a[i]=Integer.parseInt(b.readLine());          }          for(int i=0;i<5;i++)          {             if(a[i]>max)             {               max=a[i];             }          }          System.out.println("maximum number is: "+max);       }       catch(ArrayIndexOutOfBoundsException exp)       {          System.out.println("Out of the array limit...");       }       catch(IOException e)       {       }    } } Program 2 solution 23
    24. 
            
            
            
							

							

					

					
					
					

						
Related

						

						


							
							
							
							

						

							

									

      

        
          

            

              KDADS IDD Crisis Exception Training Overview
            

            

              
KDADS IDD Crisis Exception Training Overview

              
santi

            

          

        
      


     

      

        
          

            

              Java Packages and Their Importance in Programming
            

            

              
Java Packages and Their Importance in Programming

              
amberrose

            

          

        
      


     

      

        
          

            

              Proposal NPRR.1144: Station Backup Power Requirements Exception
            

            

              
Proposal NPRR.1144: Station Backup Power Requirements Exception

              
cayson

            

          

        
      


     

      

        
          

            

              Java Programming: BCA IV Semester Course Overview
            

            

              
Java Programming: BCA IV Semester Course Overview

              
smyi

            

          

        
      


     

      

        
          

            

              Single-File Source Code Programs in Java 11
            

            

              
Single-File Source Code Programs in Java 11

              
brealeigh

            

          

        
      


     

      

        
          

            

              Exception Code Table - Overview and Navigation
            

            

              
Exception Code Table - Overview and Navigation

              
deen397

            

          

        
      


     

      

        
          

            

              The Fiduciary Duty Exception to Attorney-Client Privilege
            

            

              
The Fiduciary Duty Exception to Attorney-Client Privilege

              
arienne

            

          

        
      


     

      

        
          

            

              Exception Handling in Java
            

            

              
Exception Handling in Java

              
ovid_813

            

          

        
      


     

      

        
          

            

              Packages in Java: A Comprehensive Overview
            

            

              
Packages in Java: A Comprehensive Overview

              
tete201

            

          

        
      


     

      

        
          

            

              Java Overview and Basics: Understanding the Fundamentals of Java Programming
            

            

              
Java Overview and Basics: Understanding the Fundamentals of Java Programming

              
mika_229

            

          

        
      


     

      

        
          

            

              Overview of Java Programming Language
            

            

              
Overview of Java Programming Language

              
jjya

            

          

        
      


     

      

        
          

            

              Mastering Generics in Effective Java: A Practical Guide for Java Programmers
            

            

              
Mastering Generics in Effective Java: A Practical Guide for Java Programmers

              
haydenow

            

          

        
      


     

      

        
          

            

              Differences Between C# and Java: A Comparative Overview
            

            

              
Differences Between C# and Java: A Comparative Overview

              
dewa_2

            

          

        
      


     

      

        
          

            

              Exception Handling and Interrupts in MIPS Architectures
            

            

              
Exception Handling and Interrupts in MIPS Architectures

              
abdalrah

            

          

        
      


     

      

        
          

            

              Exception Handling in Intermediate Java
            

            

              
Exception Handling in Intermediate Java

              
betances_h

            

          

        
      


     

      

        
          

            

              Exception Handling in Java: Understanding and Implementing
            

            

              
Exception Handling in Java: Understanding and Implementing

              
emo_mai

            

          

        
      


     

      

        
          

            

              Handling Exceptions in Java Programming
            

            

              
Handling Exceptions in Java Programming

              
dewa_496

            

          

        
      


     

      

        
          

            

              Java Exception Handling
            

            

              
Java Exception Handling

              
kadie

            

          

        
      


     

      

        
          

            

              Recursion in Java: CS2110 Lecture Overview
            

            

              
Recursion in Java: CS2110 Lecture Overview

              
bora_884

            

          

        
      


     

      

        
          

            

              Exception Handling in Java
            

            

              
Exception Handling in Java

              
eliannys

            

          

        
      


     

      

        
          

            

              Exception Handling in Java: Basics, Examples, and Importance
            

            

              
Exception Handling in Java: Basics, Examples, and Importance

              
tlafo

            

          

        
      


     

      

        
          

            

              Exception Handling in Java: Understanding Errors and Exceptions
            

            

              
Exception Handling in Java: Understanding Errors and Exceptions

              
jesch

            

          

        
      


     							

						

					

					

				


				

			

		
		

			

				
				

					
More Related Content

					

						

														

					

				

				
			

		












 





  
  
  



giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#