|Modifier and Type||Method and Description|
Returns an estimated number of bytes that can be read or skipped without blocking for more input.
Closes this stream.
Invoked when the garbage collector has detected that this instance is no longer reachable.
Sets a mark position in this InputStream.
Indicates whether this stream supports the
Reads a single byte from this stream and returns it as an integer in the range from 0 to 255.
Reads at most
Resets this stream to the last marked location.
Skips at most
public final int getAssetInt()
public final int read() throws IOException
public final boolean markSupported()
reset()methods. The default implementation returns
public final int available() throws IOException
Note that this method provides such a weak guarantee that it is not very useful in practice.
Firstly, the guarantee is "without blocking for more input" rather than "without blocking": a read may still block waiting for I/O to complete — the guarantee is merely that it won't have to wait indefinitely for data to be written. The result of this method should not be used as a license to do I/O on a thread that shouldn't be blocked.
Secondly, the result is a conservative estimate and may be significantly smaller than the actual number of bytes available. In particular, an implementation that always returns 0 would be correct. In general, callers should only use this method if they'd be satisfied with treating the result as a boolean yes or no answer to the question "is there definitely data ready?".
Thirdly, the fact that a given number of bytes is "available" does not guarantee that a read or skip will actually read or skip that many bytes: they may read or skip fewer.
It is particularly important to realize that you must not use this method to
size a container and assume that you can read the entirety of the stream without needing
to resize the container. Such callers should probably write everything they read to a
ByteArrayOutputStream and convert that to a byte array. Alternatively, if you're
reading from a file,
File.length() returns the current length of the file (though
assuming the file's length can't change may be incorrect, reading a file is inherently
The default implementation of this method in
InputStream always returns 0.
Subclasses should override this method if they are able to indicate the number of bytes
public final void close() throws IOException
public final void mark(int readlimit)
readlimitindicates how many bytes can be read before the mark is invalidated. Sending
reset()will reposition the stream back to the marked position provided
readLimithas not been surpassed.
This default implementation does nothing and concrete subclasses must provide their own implementation.
public final void reset() throws IOException
IOExceptionif the number of bytes read since the mark has been set is greater than the limit provided to
mark, or if no mark has been set.
This implementation always throws an
IOException and concrete
subclasses should provide the proper implementation.
public final int read(byte b) throws IOException
read(buffer, 0, buffer.length).
public final int read(byte b, int off, int len) throws IOException
lengthbytes from this stream and stores them in the byte array
b- the byte array in which to store the bytes read.
off- the initial position in
bufferto store the bytes read from this stream.
len- the maximum number of bytes to store in
IOException- if the stream is closed or another IOException occurs.
public final long skip(long n) throws IOException
nbytes in this stream. This method does nothing and returns 0 if
nis negative, but some subclasses may throw.
Note the "at most" in the description of this method: this method may choose to skip fewer bytes than requested. Callers should always check the return value.
This default implementation reads bytes into a temporary buffer. Concrete subclasses should provide their own implementation.
protected void finalize() throws Throwable
Note that objects that override
finalize are significantly more expensive than
objects that don't. Finalizers may be run a long time after the object is no longer
reachable, depending on memory pressure, so it's a bad idea to rely on them for cleanup.
Note also that finalizers are run on a single VM-wide finalizer thread,
so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary
for a class that has a native peer and needs to call a native method to destroy that peer.
Even then, it's better to provide an explicit
close method (and implement
Closeable), and insist that callers manually dispose of instances. This
works well for something like files, but less well for something like a
where typical calling code would have to deal with lots of temporaries. Unfortunately,
code that creates lots of temporaries is the worst kind of code from the point of view of
the single finalizer thread.
If you must use finalizers, consider at least providing your own
ReferenceQueue and having your own thread process that queue.
Unlike constructors, finalizers are not automatically chained. You are responsible for
Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.