Regarding closing the writers in java

[praveen oruganti]

Hi,

I am having a small doubt rgarding closing of writers in java.

I have written a method called getStackTrace in my program.

public static String getStackTrace(Throwable aThrowable) {
final StringWriter result = new StringWriter();
final PrintWriter printWriter = new PrintWriter(result);
aThrowable.printStackTrace(printWriter);
return result.toString();
}
Whether i need to close the StringWriter and PrintWriter compulsory due to unclosing of writers whether it causes any memory leak due to temporary unused java objects.

Please guide me in this regard.

[Rob Spoor]

While for some readers / writers / streams it's not necessary to explicitly close them (StringWriter and ByteArrayInputStream / -OutputStream being amonth them since these have only Java resources - no file handles or anything similar), it's always a good idea to close them anyways:

public static String getStackTrace(Throwable aThrowable) {
final StringWriter result = new StringWriter();
final PrintWriter printWriter = new PrintWriter(result);
try
{
aThrowable.printStackTrace(printWriter);
return result.toString();
}
finally
{
printWriter.close();
}
}

Also, always close the wrapping objects, not the wrapped. These wrapping objects may need to send some finalizing data, e.g. ZipOutputStream. I once had a problem where I closed its underlying stream instead, and the ZIP files were corrupted.

[praveen oruganti]

Whether it is necessary to introduce the flush for the writer before closing it.

[Campbell Ritchie]

Look at the API for flush and close; that should answer your question.

[praveen oruganti]

Yes i got it, Whenever we close the writer it will automatically calls the flush first.

[Campbell Ritchie]

 

Originally posted by praveen oruganti:
Yes i got it . . .