![Common scenarios where exceptions may occur
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](https://image.slidesharecdn.com/javachapter6-180310133851/85/Java-chapter-6-9-320.jpg)
![Example
Problem without exception handling
• Let's try to understand the problem if we
don't use try-catch block.
public class Testtrycatch1{
public static void main(String args[]){
int data=50/0;//may throw exception
System.out.println("rest of the code...");}
}
• Output:
Exception in thread main java.lang.ArithmeticException:/ by zero](https://image.slidesharecdn.com/javachapter6-180310133851/85/Java-chapter-6-13-320.jpg)
![Example …
Solution by exception handling
• Let's see the solution of above problem by java try-catch block.
public class Testtrycatch2{
public static void main(String args[]){
try{
int data=50/0;
}catch(ArithmeticException e){
System.out.println(e);}
System.out.println("rest of the code..."); } }
• Output:
Exception in thread main java.lang.ArithmeticException:/ by zero
rest of the code...](https://image.slidesharecdn.com/javachapter6-180310133851/85/Java-chapter-6-14-320.jpg)
Java chapter 6
- 2. Outline • Exception handling overview • Syntax
- 3. Exception handling overview • The exception handling in java is one of the powerful mechanism to handle the runtime errors so that normal flow of the application can be maintained. • In java, exception is an event that disrupts the normal flow of the program. It is an object which is thrown at runtime.
- 4. Cont… • Exception Handling is a mechanism to handle runtime errors such as ClassNotFound, IO, SQL, Remote etc. • The core advantage of exception handling is to maintain the normal flow of the application.
- 5. Hierarchy of Java Exception classes
- 6. Types of Exception • There are mainly two types of exceptions: checked and unchecked where error is considered as unchecked exception. • According to the sun microsystem says there are three types of exceptions: 1. Checked Exception 2. Unchecked Exception 3. Error
- 7. Cont… 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. 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. Error • Error is irrecoverable e.g. OutOfMemoryError, VirtualMachineError, AssertionError etc.
- 8. Common scenarios where exceptions may occur 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 a NullPointerException. String s=null; System.out.println(s.length());//NullPointerException
- 9. Common scenarios where exceptions may occur 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
- 10. Java Exception Handling Keywords • There are 5 keywords used in java exception handling. Try Catch Finally Throw 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){}
- 12. Cont… Syntax of try-catch-finally block try{ //code that may throw exception } catch(Exception_class_Name ref){ } finally{}
- 13. Example Problem without exception handling • Let's try to understand the problem if we don't use try-catch block. public class Testtrycatch1{ public static void main(String args[]){ int data=50/0;//may throw exception System.out.println("rest of the code...");} } • Output: Exception in thread main java.lang.ArithmeticException:/ by zero
- 14. Example … Solution by exception handling • Let's see the solution of above problem by java try-catch block. public class Testtrycatch2{ public static void main(String args[]){ try{ int data=50/0; }catch(ArithmeticException e){ System.out.println(e);} System.out.println("rest of the code..."); } } • Output: Exception in thread main java.lang.ArithmeticException:/ by zero rest of the code...
- 15. Internal working of java try-catch block