Thread: Resource leak

what does this mean? and how do I fix this issue?

resource leak:'input1' is never closed

many thanks.

If a class implements the interface Closeable and you create a new instance of this class then you are also supposed to call the "close()" method on the object at some point in time.
If you dont the compiler might generate a warning just like the one you have posted.

Thank you Cornix.
I actually just ended up converted local variable to field. It fixed the problem, but I have no idea why this fixes the problem. Do you mind explaining please. thank you

Originally Posted by wamidh

Thank you Cornix.
I actually just ended up converted local variable to field. It fixed the problem, but I have no idea why this fixes the problem. Do you mind explaining please. thank you

Because the compiler is not smart enough to detect that you are doing something wrong and therefor does not give out a warning. But the actual problem is not solved at all, it has just been hidden from the view of the compiler.

The actual solution would be to call the close() method on your object once you dont need it anymore, as I have explained in my first post.

oh. how do I use close()
do I type in close(input1) ;
thank you Cornix

--- Update ---

ah, thank you Ada

If you have a variable of type Closeable then it has a close() method.
For example:

Closeable someCloseable = new Scanner(System.in);
someCloseable.close();

Because the Scanner class is implementing the interface Closeable. Other Closeables could be all kinds of Output- or InputStream's

Originally Posted by aussiemcgr

If you are using Java 7 or above, you can use the try-with-resource:

try (Closeable someCloseable = new Scanner(System.in)) {
...
}

If I am to understand the Oracle documentation correctly, that should automatically close the resource when the try block is exited.

Yes, and this is the best habit to get into. No more try { ... } finally { ... } blocks for something as mundane (and easy to forget) as invoking .close(). Especially when your finally block has to handle even more checked exceptions.

Only if the class is implementing the interface AutoCloseable which the Scanner class actually does, so it should work.
But not every Closeable is neccessarily an AutoCloseable as well.

thank you everybody!