Question

Write a try/catch/finally clause to catch one or more specific Exception objects in Java.

Answer 1

Program with its explanation:

Keyword	Description
Try	Suspicious code that might throws an error and stops the program execution should be written in try block
Catch	Exceptions occured in the code are handled by catch blocks; as the name suggests it catches the exceptions
Finally	Important code/information in our program that needs to be executed irrespective of whether or not the exception is thrown.
Throw	it throw exception explicitly
Throws	it does not throw an exception but is used to declare exceptions.

Multiple programs are listed so that you can understand the concept :

Program 1:

public class TryCatchFinally {

   public static void main(String[] args) {
       try
       {
       System.out.println("try block");
       }
       catch (Exception e)
       {
       System.out.println("catch block");
       }
       finally
       {
       System.out.println("finally block");
       }
   }
}

Ouput:

try block
finally block

Explanation: Since there is no suspicious code in try block so catch block doesnt comes into picture.

Program 2:

public class TryCatchFinally {

   public static void main(String[] args) {
       int num1, num2;
       int div;
   try {
  
       Scanner sc =new Scanner(System.in);
       System.out.println("enter num1");
       num1=sc.nextInt();
       System.out.println("enter num2");
       num2=sc.nextInt();
  
       System.out.println("num1/num2 is="+num1+"/"+num2);
   div = num1 / num2; // anything divided by zero is infinite so it is going to throw exception
   System.out.println("result is="+div);
   System.out.println("end of try block");
   }
   catch (ArithmeticException e) {
   // blocks only Arithmetic exception occurs in try block
   System.out.println("ArithmeticException Occurred !! You should not divide a number by zero");
   }
   catch (Exception e) {
   // This is a generic Exception handler
   System.out.println("generic Exception occurred !!");
   }
   finally
           {
           System.out.println("finally block");
           }

   }
}
Output:

enter num1
10
enter num2
0
num1/num2 is=10/0
ArithmeticException Occurred !! You should not divide a number by zero
finally block

Program3.1:

public class TryCatchFinally {

   public static void main(String[] args) {
  
           try{
           int a[]=new int[7]; // array of 7 values 0 to 6
           a[1]=10/0;// using second index i.e. 1 and divide by zero throws Arithematic exception
           System.out.println("First print statement in try block");
           }
           catch(ArithmeticException e){
           System.out.println("Warning: ArithmeticException");
           }
           catch(ArrayIndexOutOfBoundsException e){
           System.out.println("Warning: ArrayIndexOutOfBoundsException");
           }
           catch(Exception e){
           System.out.println("Warning: Some Other exception");
           }          
          
   finally
           {
           System.out.println("finally block");
           }

   }
}

Output:

Warning: ArithmeticException
finally block

Program3.2:

import java.io.IOException;
import java.util.Scanner;

import javax.imageio.IIOException;

public class TryCatchFinally {

   public static void main(String[] args) {
  
           try{
           int a[]=new int[7]; // array of 7 values 0 to 6
           a[9]=10/2;// using 10th index i.e. 9 and throws ArrayIndexOutOfBoundsException bcz array if of 7 // values
           System.out.println("First print statement in try block");
           }
           catch(ArithmeticException e){
           System.out.println("Warning: ArithmeticException");
           }
           catch(ArrayIndexOutOfBoundsException e){
           System.out.println("Warning: ArrayIndexOutOfBoundsException");
           }
           catch(Exception e){
           System.out.println("Warning: Some Other exception");
           }          
          
   finally
           {
           System.out.println("finally block");
           }

   }
}

Output:

Warning: ArrayIndexOutOfBoundsException
finally block

Program4:

public class TryCatchFinally {

   public static void main(String[] args) {
  
       try
       {
       System.out.println("try block");
         
       throw new NullPointerException("null occurred");
       }
       catch (NumberFormatException e)
       {
       System.out.println("catch block 1");
       }
       catch (NullPointerException e)
       {
       System.out.println("catch block 2");
       }
       catch (Exception e)
       {
       System.out.println("catch block 3");
       }
       finally
       {
       System.out.println("finally block");
       }
   }
}

Output:

try block
catch block 2
finally block

Explanation: catch block 2 because specific exception was mentioned i.e. nullpointerexception and it goes to specific block. If you comment out Catch2 block then it is going to print

try block
catch block 3
finally block

as generic exception block then catches the exception and prints the code inside it.

Program5:

public class TryCatchFinally {

       public static void main(String[] args) {
      
           try
           {
           System.out.println("try block");
             
           throw new NullPointerException("Null occurred");
           }
           finally
           {
           System.out.println("finally block");
           }
       }
   }

Output:

try block
finally block
Exception in thread "main" java.lang.NullPointerException: Null occurred
   at Threadds.TryCatchFinally.main(TryCatchFinally.java:18)

Explanation: SInce no catch block is there to handle the exception so it is going to throw the exception.

Program6:

public class TryCatchFinally {
   void testMethod(int num) throws IOException, ArithmeticException{
   if(num==1)
   throw new IOException("IOException Occurred");
   else
   throw new ArithmeticException("ArithmeticException");
   }
  
   public static void main(String args[]){
   try{
       TryCatchFinally obj=new TryCatchFinally();
   obj.testMethod(1);
   }catch(Exception ex){
   System.out.println(ex);
   }
   }
   }

Output:

java.io.IOException: IOException Occurred

Explanation: If   obj.testMethod(2); is written it gives output as  java.lang.ArithmeticException: ArithmeticException
as it is defining exceptions explicitly.

Program7:

public class TryCatchFinally {

   public static void main(String[] args) {
       int num1, num2;
       int div;
   try {
  
       Scanner sc =new Scanner(System.in);
       System.out.println("enter num1");
       num1=sc.nextInt();
       System.out.println("enter num2");
       num2=sc.nextInt();
  
       System.out.println("num1/num2 is="+num1+"/"+num2);
   div = num1 / num2;
   System.out.println("result is="+div);
   System.out.println("end of try block");
   }
   catch (ArithmeticException e) {
   System.out.println("You should not divide a number by zero");
   e.printStackTrace();
   }
   catch (Exception e) {
   System.out.println("Exception occurred");
   e.printStackTrace();
   }
   finally
           {
           System.out.println("finally block");
           }

   }
}
Output:

enter num1
10
enter num2
0
num1/num2 is=10/0
You should not divide a number by zero
finally block
java.lang.ArithmeticException: / by zero
   at Threadds.TryCatchFinally.main(TryCatchFinally.java:23)

Explanation: e.printStackTrace(); is a method of Java’s throwable class which prints the throwable along with other details like the line number and class name where the exception occurred.

NOTE: Please add necessary import statements to execute the program smoothly.