The document discusses Java exception handling concepts. It explains that multiple catch blocks can be used to catch different types of exceptions, with the first matching exception handler executing. Finally blocks provide code that is always executed after a try/catch block, such as for cleanup. Finally blocks ensure code is executed whether an exception occurs or not.

1. The concept of multi-catch
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2. Objectives
On completion of this period, you would be able to
know :
• The concept of multi-catch statements
• The usage of finally block
• Related programs
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3. Recap
In the last class, you have studied about the usage of
Java keywords
• We have also written simple program using try and
catch
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4. Multiple catch Statements
1. Some times more than one exception can be
raised
2. You can specify two or more catch blocks, each
catching a different type of exception
3. When an exception is thrown, each catch block
is inspected in order
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5. Multiple catch Statements Contd..
1. First exception handler whose type matches that
of the generated exception is executed
2. If any one catch statement executes, the others
are bypassed, and execution continues after the
try/catch block
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6. Java Program Using Multi-catch
// program for multiple catch statements
class MultiCatch {
public static void main(String args[]) {
try {
int a = args.length;
System.out.println("a = " + a);
int b = 42 / a;
int c[] = { 1 };
c[42] = 99;
} catch(ArithmeticException e) {
System.out.println("Divide by 0: " + e);
} catch(ArrayIndexOutOfBoundsException e) {
System.out.println("Array index Out of bounds: " + e);
}
System.out.println("After try/catch blocks.");
}
}
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7. Explanation :
• This program catches two exceptions, namely
• ArithmeticException
• ArrayIndexOutOfBoundsException
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8. throw Statement
• So far, we have dealt with exceptions that are
thrown by Java run-time system
• It is possible for your program to throw an
exception explicitly, using the throw statement
• The general form of throw is shown here
throw exceptionObject;
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9. throws Clause
• A throws clause lists the types of exceptions that a
method might throw
• This is necessary for all exceptions, except those of
type Error or RuntimeException, or any of their
subclasses
• All other exceptions that a method can throw must
be declared in the throws clause
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10. throws Clause contd..
• General form of a method declaration that includes a
throws type method
• ret-type name(parameter-list) throws exception-list
{
// body of method
}
• Here, exception-list is a comma-separated list of
exception names
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11. finally Block
• finally block creates a block of code that will be
executed after a try/catch block has completed
• And before the code following the try/catch block
• The finally block is compulsorily executed
whether or not an exception is thrown
• If an exception is thrown, the finally block will
execute even if no catch statement matches the
exception
• finally block is useful for doing clean-up work
e.g. : To close an opened file
To close a database connection etc
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12. An Example For finally Block
class finallyDemo {
public static void main(String[] args){
int [] a= new int [5];
try{
for(int i=0; i<=5; i++){
a[i] = (i-1)/i;
System.out. println(a[i]);
}
}catch (Exception e){
System. out. println(e);
}finally{
System. out. println(“this line is certainly printed”);
}
}
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}

13. Explanation
• The above program ones finally block
• It generates ‘ArithmeticException’ as division by
zero occurs
• The statement in finally block will be compulsorily
executed
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14. Discussion
• Give one situation for using multi-catch statement
• In file processing
• What is the purpose of ‘finally’ block
• To do clean-up code
• How many ‘finally’ block can be there for one try
block
• One is enough
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15. Summary
• Some times more than one exception can be raised
• You can specify two or more catch clauses, each
catching a different type of exception
• The finally block will execute whether or not an
exception is thrown
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16. Quiz
1. We can not raise more than one exception
A. True
B. False
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17. Quiz
2. A throws clause lists the types of exceptions that a
method might throw
A. True
B. False
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18. Frequently Asked Questions
1. Explain the concept of multi-catch statements
2. Explain how nested try statement can be used
3. Explain the throw and throws clauses
4. Write a sample Java program to demonstrate use
of multiple catches
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