Return

[Vladimir Kositsky]

class Nan 
{
static float Parse(String s)
{

float f = 0.0f;
try{
f = Float.valueOf( s ).floatValue();
System.out.println("Float number" + f);
return f;
}
catch( NumberFormatException nfe)
{
System.out.println("Not a number" + s);
f = Float.NaN;
//return f;      /////////// "A"
}
finally
{
System.out.println("Hello World!");
}
return f;
}

public static void main(String[] args) 
{
Parse(args[0]);
}
}

This piece of code will not compile if line A added.
Any ideas?

[This message has been edited by Vladimir Kositsky (edited January 11, 2001).]

[sasi dhulipala]

Actually what is that you want from the code you have given ?
Sasidhar

[Vlad G]

The compiler is smart to detect that return statement after finally will never be executed that's why it complains...

[Cherry Mathew]

[B]

class Nan 
{
static float Parse(String s)
{

float f = 0.0f;
try{
f = Float.valueOf( s ).floatValue();
System.out.println("Float number" + f);
// return f;  // if u comment out this line it will compile 
}
catch( NumberFormatException nfe)
{
System.out.println("Not a number" + s);
f = Float.NaN;
        return f;      /////////// "A"
}
finally
{
System.out.println("Hello World!");
}
return f;
}

public static void main(String[] args) 
{
Parse(args[0]);
}
}

Hi
i have made some change to the original code
i ve removed the comment before the return inside the catch block and commneted out the retrun inside the try block
if u comment out the return inside the code will compile bcoz the return statement at the end of the try block will be used but if the program is not throwing any exception then programn will use the return inside the try block and return in exception is used if exception thrown we have to be very carefull bcoz compiler is very intelligent
If some question like this comes we have to see the question first anf then try all the possibilities of throwing an exception real problem comes when they wont specify what the error is .
Cherry

[This message has been edited by Cherry Mathew (edited January 11, 2001).]

[Vladimir Kositsky]

Thanks

[vadiraj vd]

Hi,
I'm totally agree with Vlad G.
The compiler is intelligent enough to find out where the return
statements are.
In your code there's a return in try, catch and finally.
So if any exception occurs the code after the finally will not
be executed.
Well Vladimir nice example to show that
the java compiler IS intelligent.


------------------
Regards
---------
vadiraj

*****************
There's a lot of I in J.
*****************

[mohammed mustafa]

after exception has occured the program code in try -catch are executed
after which it is mandatory to transfer control to finally and return
is not just a statement but it is control transfering statement and compiler
knows it better hence it is never executed in such cases . And after finally
the method which gave the exception is aborted and the program flow is continued.

------------------

[sunil choudhary]

http://www.javaranch.com/ubb/Forum24/HTML/007186.html
Cherry consider this sitution
in a try block there are 15 diffferent methods and a exception is generated at the 2nd line even then the whole try block will be executed and only then will the compiler move to catch block where the exceoption is called.
I am of the view that once an exception is generated then and there itself the compiler should move to the catch block and then if there is a return stattemnt then it should not execute at all
I think that problem is not the return statement but it is
-finally is the last piece of code.(try to put System .out.printl n after finally and the compiler issues same message.
Please do correct me if you find any contradiction.
--------------------------------------------------
Logic is the art of non contradictory existence
Ayn Rand -Atlas Shrugged

[Cherry Mathew]

Hi Sunil,
U r right the compiler will give u the same message if u put any statement after the finally block bcoz in all the cases (even if exception occurs or not) the statement is not reached.
Compiler can check for these cases
I havent tried this but try writing some statement after a throw statement to throw an exception. It will give u an error statement not reached
Cherry