Github user rwm commented on the issue:
https://github.com/apache/jena/pull/133
I would strongly vote for adding the AutoCloseable interface, at least for
StmtIterator. The sole purpose of AutoCloseable is to allow developers to use
the `try-with-resources` statement and it does not cause any side effects. When
it was introduced to Java, the interface was added to all objects with a
`close()` method.
The javadoc for AutoCloseable says:
> An object that may hold resources (such as file or socket handles) until
it is closed. The close() method of an AutoCloseable object is called
automatically when exiting a try-with-resources block for which the object has
been declared in the resource specification header. This construction ensures
prompt release, avoiding resource exhaustion exceptions and errors that may
otherwise occur.
>API Note:
> It is possible, and in fact common, for a base class to implement
AutoCloseable even though not all of its subclasses or instances will hold
releasable resources. For code that must operate in complete generality, or
when it is known that the AutoCloseable instance requires resource release, it
is recommended to use try-with-resources constructions. However, when using
facilities such as Stream that support both I/O-based and non-I/O-based forms,
try-with-resources blocks are in general unnecessary when using non-I/O-based
forms.
@afs do you have a list of the generated warnings and maybe could attach
them in a file so we can review them?
In my experience, the warnings are mostly useful hints about missing close
statements. You can disable them via `@SuppressWarnings("resource")` or by
compiling with `-source 7`.
See the following example:
```
private class C implements AutoCloseable{
@Override
public void close() {
}
}
public void a(){
C c = new C();
// warning! never closed
Objects.requireNonNull(c);
}
public void b(){
C c = new C();
Objects.requireNonNull(c);
c.close();
// no warning, the instance is closed
}
public C c(){
C c = new C();
Objects.requireNonNull(c);
// no warning, the instance is returned
return c;
}
public void d(){
C c = new C();
if( new Random().nextFloat() < 0.2 ){
// warning! not closed at this location
return;
}
c.close();
}
```
The AutoCloseable interface should be used on any class with a `close()`
method, which may need to be called. Otherwise developers are forced to use
Java 6 code with manual exception handling for resource.
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