Can we use finaly block to catch exceptions without using catch block?

[Nagaraj Shivaklara]

Hi All,

I have two questions:

1) Can we use finally block to catch exceptions without using catch block after the try block?

2) Can we write finally block before catch block? like below :
In the below case where should we catch exceptions? (in finally block or catch block)
try
{

}
finally{

}
catch()
{
}

[Prasad Kharkar]

We cannot use finally block to catch exceptions
what the finally block means that whatever we write in the finally block, it is executed regardless the exception is thrown or not

try {
    // some risky code
}catch(Exception e){
    //this is executed if and exception is thrown
}finally{
   //this is always executed
}

[Prasad Kharkar]

we cannot wrote

try{
}
finally{
}catch(Exception e){
}

above is completely wrong

[Seetharaman Venkatasamy]

Invalid Idiom!

<edit>
as a side note : for better practice, even finally block should not throw an exception, i.e, finally block should not complete execution abruptly!
</edit>

[Nagaraj Shivaklara]

Hi Prasad,

I agree with you, but we can write finally after the try block without catch block is still valid right?

In the above case what if try block thows some exceptions!!! where do we need to catch them?

I hope you got my point.

Thanks in Advance
Nagaraj SK

Prasad Kharkar wrote:We cannot use finally block to catch exceptions
what the finally block means that whatever we write in the finally block, it is executed regardless the exception is thrown or not

try {
    // some risky code
}catch(Exception e){
    //this is executed if and exception is thrown
}finally{
   //this is always executed
}

[Seetharaman Venkatasamy]

Nagaraj Shivaklara wrote:In the above case what if try block thows some exceptions!!! where do we need to catch them?

<edit>Prasad mentioned that earlier </edit>

Prasad Kharkar wrote:
what the finally block means that whatever we write in the finally block, it is executed regardless the exception is thrown or not

[Prasad Kharkar]

yes
we can write finally block even if we are not writing the catch block
but this does not mean that we are catching the exception in the try block (I think this is where you are mistaken)
the method in which we are writing this try block and directly finally block does not handle the exception
if we do not handle the exception , then we need to declare that the method throws exception but this is not required for the RuntimeException
see the code for more clarification

 
public void method(){
	try{
		// some code that can throw exception
	}catch (Exception e){
	
	}finally{
		// this is okk
	}
}

public void method (){
	try{
		// some risky code here 
	}finally{
		// this is finally block
	}

/* Here the catch block is absent i.e. we have not handled the exception here 
 * it checked exception occurs here, then the compiler will complain
 * but if it is unchecked exception then the compiler is happy
 */
}    

 public void method() {
	try{
		throw new IOException();
	}finally{
		// finally
	}
/* This code will cause compiler error as the exception thrown in try is not handled 
 * and also not declared to be thrown
 */
}

public void method() throws IOException{
	try{
		throw new IOException();
	}finally{
		// finally
	}
/* This code will not cause compiler error as the exception thrown in try is not handles but 
 * it is declared to be thrown now
 */
}
   

hope this helps now

[Nagaraj Shivaklara]

Thanks a lot Prasad, now i understood.

Prasad Kharkar wrote:yes
we can write finally block even if we are not writing the catch block
but this does not mean that we are catching the exception in the try block (I think this is where you are mistaken)
the method in which we are writing this try block and directly finally block does not handle the exception
if we do not handle the exception , then we need to declare that the method throws exception but this is not required for the RuntimeException
see the code for more clarification

 
public void method(){
	try{
		// some code that can throw exception
	}catch (Exception e){
	
	}finally{
		// this is okk
	}
}

public void method (){
	try{
		// some risky code here 
	}finally{
		// this is finally block
	}

/* Here the catch block is absent i.e. we have not handled the exception here 
 * it checked exception occurs here, then the compiler will complain
 * but if it is unchecked exception then the compiler is happy
 */
}    

 public void method() {
	try{
		throw new IOException();
	}finally{
		// finally
	}
/* This code will cause compiler error as the exception thrown in try is not handled 
 * and also not declared to be thrown
 */
}

public void method() throws IOException{
	try{
		throw new IOException();
	}finally{
		// finally
	}
/* This code will not cause compiler error as the exception thrown in try is not handles but 
 * it is declared to be thrown now
 */
}
   

hope this helps now