Should this input stream be closed?

[barock]

I have a method which returns a file as input stream as below.

public InputStream getInpStream(){

..
...
return Thread.currentThread().getContextClassLoader().get ResourceAsStream(fileName);
}

And in the invoking method I use this input stream to do a castor mapping as below. My question is should a instance of input stream be explicitly created to close this stream later?

Public Mapping returnMapping(){

Mapping mapping = new Mapping();

mapping.loadMapping(new InputSource(getInpStream()));
return mapping;
}

Thanks

[JosAH]

Strictly speaking you don't have to close the InputStream because the appropriate Streams close themselves in their finalize() method. It doesn't harm to close it because an open file (or a socket etc.) is a resource and if you don't need it, better get rid of it asap.

kind regards,

Jos

[barock]

Thanks Jos.

Looks I cannot close it in the finally block of my returnMapping() method as the mapping object retunred from thsi method still references the input stream and when the I access the mapping object down the lane, I get "Stream Already Closed"

Public Mapping returnMapping(){

Mapping mapping = new Mapping();
try{
InputStream inpStream = getInpStream();
mapping.loadMapping(new InputSource(inpStream);
}Catch(Exception e) {

}finally{
if(null != inpStream){
inpStream.close();
}
}
return mapping;
}

[JosAH]

Thanks Jos.

Looks I cannot close it in the finally block of my returnMapping() method as the mapping object retunred from thsi method still references the input stream and when the I access the mapping object down the lane, I get "Stream Already Closed"

Public Mapping returnMapping(){

Mapping mapping = new Mapping();
try{
InputStream inpStream = getInpStream();
mapping.loadMapping(new InputSource(inpStream);
}Catch(Exception e) {

}finally{
if(null != inpStream){
inpStream.close();
}
}
return mapping;
}

That code doesn't compile because variable inpStream is out of scope in your finally block ...

kind regards,

Jos

[barock]

my bad..Thats a typo in the process of editing the code manually to post it here..The inputstream is declared outside the try..

[JosAH]

my bad..Thats a typo in the process of editing the code manually to post it here..The inputstream is declared outside the try..

Ok, assuming the code is correct, where does your mapping object try to use that InputStream (after you have closed it)? (btw. it is always fine not to close it yourself for reasons I mentioned in my first reply).

kind regards,

Jos

[JosAH]

my bad..Thats a typo in the process of editing the code manually to post it here..The inputstream is declared outside the try..

Ok, assuming the code is correct, where does your mapping object try to use that InputStream (after you have closed it)? (btw. it is always fine not to close it yourself for reasons I mentioned in my first reply).

kind regards,

Jos

[barock]

Yes Jos..The mapping object was accessed after I closed the input stream in the finally block and Thanks for the suggestion - barock

[JosAH]

Yes Jos..The mapping object was accessed after I closed the input stream in the finally block and Thanks for the suggestion - barock

What is a Mapping object? I don't know what it is but it seems strange to me that, after loading, it wants to read from the InputStream again ...

kind regards,

Jos