Can somebody please explain me the output

[Padma Asrani]

Hi

I have come across one more question in java blackbelt

I am not able to understand the output.

 
public class A {
02: 
03:   private void test() throws RuntimeException, Exception {
04:     try {
05:       throw new Exception("A");
06:     } catch (Throwable t) {
07:       throw new Exception("B");    
08:     } finally {
09:       throw new Exception("C");
10:     }
11:   }
12: 
13:   public static void main(String[] args) {
14:     try {
15:       new A().test();
16:     } catch (RuntimeException e) {
17:       System.out.println("A" + e.getMessage());
18:     } catch (Exception e) {
19:       System.out.println("B" + e.getMessage());
20:     } catch (Throwable e) {
21:       System.out.println("C" + e.getMessage());
22:     }
23:   }
24: } 

The output is BC

Regards
PAdma

[Keith Lynn]

Originally posted by Padma Asrani:
Hi

I have come across one more question in java blackbelt

I am not able to understand the output.

 
public class A {
02: 
03:   private void test() throws RuntimeException, Exception {
04:     try {
05:       throw new Exception("A");
06:     } catch (Throwable t) {
07:       throw new Exception("B");    
08:     } finally {
09:       throw new Exception("C");
10:     }
11:   }
12: 
13:   public static void main(String[] args) {
14:     try {
15:       new A().test();
16:     } catch (RuntimeException e) {
17:       System.out.println("A" + e.getMessage());
18:     } catch (Exception e) {
19:       System.out.println("B" + e.getMessage());
20:     } catch (Throwable e) {
21:       System.out.println("C" + e.getMessage());
22:     }
23:   }
24: } 

The output is BC

Regards
PAdma

The method test() does not throw an exception to the main method.

The exception is thrown and caught within the try/catch block inside test() and prints out B. The finally block executes and prints out C.

[Prashanth Tonupunuri]

hi padma ji..what is java blackbelt...i donno can you tell me...

[Bharat Makwana]

Hi Keith,

Originally posted by Keith Lynn:


The method test() does not throw an exception to the main method.

The exception is thrown and caught within the try/catch block inside test() and prints out B. The finally block executes and prints out C.

Exception is propagated to main method.The exception which is thrown by finally block in test() method is passed to main method. see following code

public class Test {
 
   private void test() throws RuntimeException, Exception {
     try {
       throw new Exception("A");
     } catch (Throwable t) {
       throw new Exception("B");    
     } finally {
       throw new Exception("C");
    }
   }
 
   public static void main(String[] args) {
     try {
       new Test().test();
     } catch (RuntimeException e) {
       System.out.println("A_A" + e.getMessage());
     } catch (Exception e) {
       System.out.println("B_B " + e.getMessage());
     } catch (Throwable e) {
       System.out.println("C_C" + e.getMessage());
     }
   }
 } 

Output is
B_B C

[khushhal yadav]

Hi Bharat Makwana

It's because you are throwing an exception here

finally {
throw new Exception("C");
}

And finally is going to be executed in any case..

So that has to be declare or handle in main()

Hence the code

catch (Exception e) {
System.out.println("B_B " + e.getMessage());
}

will be executed
And you will get
"B_B " + "C"( for e.getMessage())

i.e. B_B C as output..

Regards..

[dhwani mathur]

Please can anybody can ellaborate and explain the above given program,

how the main method does not throw exception?

Here the method is called in the try catch block as well as the method itself consist of of try catch block,so i am bit confused .

[khushhal yadav]

Hi dhwani mathur

how the main method does not throw exception?

Because the rule is declare or handle..

Since you are properly handling the exception in main()
by using try and catch block..

You need not to declare them in main using throws keyword..

Regards..

[dhwani mathur]

hi!!
Khushhal
Thank you for your explanation,i got the point.

[Padma Asrani]

hello Everyone,

Thanks a lot for the replies but I am still a bit confused about the test method.

    
private void test() throws RuntimeException, Exception {
     try {
       throw new Exception("A");
     } catch (Throwable t) {
       throw new Exception("B");    
     } finally {
       throw new Exception("C");
    }
   }
 
   public static void main(String[] args) {
     try {
       new Test().test();
     } catch (RuntimeException e) {
       System.out.println("A_A" + e.getMessage());
     } catch (Exception e) {
       System.out.println("B_B " + e.getMessage());
     } catch (Throwable e) {
       System.out.println("C_C" + e.getMessage());
     }
   }
 } 

When we are inside the test method then once the exception is thrown for the first time then it was caught by the subsequent catch clause but what happens to the exception which was thrown within the catch clause? So after that finally has to be executed, so it again throws the exception which we catching in the main() method. So the output is

B_B C

but again what happens to the exception which was thrown within the catch clause of test method. I thought it should be caught within the main method but indeed it is not.
Can you guys explain me why is that?

Regards
Padma

[Keith Lynn]

Originally posted by Bharat Makwana:
Hi Keith,


Exception is propagated to main method.The exception which is thrown by finally block in test() method is passed to main method. see following code

public class Test {
 
   private void test() throws RuntimeException, Exception {
     try {
       throw new Exception("A");
     } catch (Throwable t) {
       throw new Exception("B");    
     } finally {
       throw new Exception("C");
    }
   }
 
   public static void main(String[] args) {
     try {
       new Test().test();
     } catch (RuntimeException e) {
       System.out.println("A_A" + e.getMessage());
     } catch (Exception e) {
       System.out.println("B_B " + e.getMessage());
     } catch (Throwable e) {
       System.out.println("C_C" + e.getMessage());
     }
   }
 } 

Output is
B_B C

Oops. Sorry. You're right. I didn't read it close enough.