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StreamFinalizer.javaAPI DocJava SE 6 API2183Tue Jun 10 00:21:54 BST 2008com.sun.imageio.stream

StreamFinalizer

public class StreamFinalizer extends Object
Small class to assist in properly closing an ImageInputStream instance prior to garbage collection. The ImageInputStreamImpl class defines a finalize() method, but in a number of its public subclasses (e.g. FileImageInputStream) we override the finalize() method to be empty for performance reasons, and instead rely on the Disposer mechanism for closing/disposing resources. This is fine when one of these classes is instantiated directly (e.g. new FileImageInputStream()) but in the unlikely case where a user defines their own subclass of one of those streams, we need some way to get back to the behavior of ImageInputStreamImpl, which will call close() as part of finalization. Typically an Image{Input,Output}Stream will construct an instance of StreamFinalizer in its constructor if it detects that it has been subclassed by the user. The ImageInputStream instance will hold a reference to the StreamFinalizer, and the StreamFinalizer will hold a reference back to the ImageInputStream from which it was created. When both are no longer reachable, the StreamFinalizer.finalize() method will be called, which will take care of closing down the ImageInputStream. Clearly this is a bit of a hack, but it will likely only be used in the rarest of circumstances: when a user has subclassed one of the public stream classes. (It should be no worse than the old days when the public stream classes had non-empty finalize() methods.)

Fields Summary
private ImageInputStream
stream
Constructors Summary
public StreamFinalizer(ImageInputStream stream)

        this.stream = stream;
Methods Summary
protected voidfinalize()

        try {
            stream.close();
        } catch (IOException e) {
        } finally {
            stream = null;
            super.finalize();
        }