On 23 Apr 2015, at 22:24, Roger Riggs <roger.ri...@oracle.com> wrote:
> Hi Pavel,
>
> On 4/23/2015 5:12 PM, Pavel Rappo wrote:
>> Hey Roger,
>>
>> 1. Good catch! This thing also applies to java.io.InputStream.read(byte[],
>> int, int):
Yes, good catch indeed.
>> * <p> In every case, elements <code>b[0]</code> through
>> * <code>b[off]</code> and elements <code>b[off+len]</code> through
>> * <code>b[b.length-1]</code> are unaffected.
>>
>> I suppose the javadoc for the method proposed by Chris has started its life
>> as a
>> copy of the javadoc read(byte[], int, int) which was assumed to be perfectly
>> polished. Unfortunately it was a false assumption.
> it happens... many many people have read those descriptions (or didn't
> because
> it was too obvious or thought to be redundant).
I propose this small amendment.
* <p> In the case where {@code off > 0}, elements {@code b[0]} through
* {@code b[off-1]} are unaffected. In every case, elements
* {@code b[off+len]} through {@code b[b.length-1]} are unaffected.
>>
>> 2. About awkward sentences. This paragraph also has to be rephrased for the
>> same reason:
>>
>> * <p> The first byte read is stored into element {@code b[off]}, the
>> next
>> * one in to {@code b[off+1]}, and so on. The number of bytes read is, at
>> * most, equal to {@code len}. Let <i>k</i> be the number of bytes
>> actually
>> * read; these bytes will be stored in elements {@code b[off]} through
>> * {@code b[off+}<i>k</i>{@code -1]}, leaving elements {@code
>> b[off+}<i>k</i>
>> * {@code ]} through {@code b[off+len-1]} unaffected.
>>
>> If k == 0 then spec claims to store values in b[off]... b[off - 1].
Reading the whole method description leads to be believe that 'k' cannot equal
0 at this point. The previous paragraph handles the case where len is 0. The
previous paragraph to that handles the EOF case. This paragraph implicitly
implies that k is greater than 0, “The first byte read”, and “the number of
actual bytes read”, neither of which can be 0 at this point.
I included below [*] the latest version of this method, including all comments
so far.
> If one concludes that's an empty interval then its ok; it just reads oddly
> and can
> make the reader think its wrong.
> In some cases it is easier if the upper bound is defined to be exclusive.
> Then if lower == upper, its empty.
>
> If better language were constructed for the new method then perhaps it could
> be worked back into methods with similar behavior later. If the wording
> changes
> in any significant way, the conformance team will have to go back and
> re-evaluate
> it in detail to see if it really has changed. So I'd leave it alone.
>
> Roger
-Chris.
[*]
/**
* Reads some bytes from the input stream into the given byte array. This
* method blocks until {@code len} bytes of input data have been read, end
* of stream is detected, or an exception is thrown. The number of bytes
* actually read, possibly zero, is returned. This method does not close
* the input stream.
*
* <p> In the case where end of stream is reached before {@code len} bytes
* have been read, then the actual number of bytes read will be returned.
* When this stream reaches end of stream, further invocations of this
* method will return zero.
*
* <p> If {@code len} is zero, then no bytes are read and {@code 0} is
* returned; otherwise, there is an attempt to read up to {@code len} bytes.
*
* <p> The first byte read is stored into element {@code b[off]}, the next
* one in to {@code b[off+1]}, and so on. The number of bytes read is, at
* most, equal to {@code len}. Let <i>k</i> be the number of bytes actually
* read; these bytes will be stored in elements {@code b[off]} through
* {@code b[off+}<i>k</i>{@code -1]}, leaving elements {@code b[off+}<i>k</i>
* {@code ]} through {@code b[off+len-1]} unaffected.
*
* <p> In the case where {@code off > 0}, elements {@code b[0]} through
* {@code b[off-1]} are unaffected. In every case, elements
* {@code b[off+len]} through {@code b[b.length-1]} are unaffected.
*
* <p> In every case, elements {@code b[0]} through {@code b[off-1]} and
* elements {@code b[off+len]} through {@code b[b.length-1]} are unaffected.
*
* <p> The behavior for the case where the input stream is <i>asynchronously
* closed</i>, or the thread interrupted during the read, is highly input
* stream specific, and therefore not specified.
*
* <p> If an I/O error occurs reading from the input stream, then it may do
* so after some, but not all, bytes of {@code b} have been updated with
* data from the input stream. Consequently the input stream and {@code b}
* may be in an inconsistent state. It is strongly recommended that the
* stream be promptly closed if an I/O error occurs.
*
* @param b the buffer into which the data is read
* @param off the start offset in {@code b} at which the data is written
* @param len the maximum number of bytes to read
* @return the actual number of bytes read into the buffer
* @throws IOException if an I/O error occurs
* @throws NullPointerException if {@code b} is {@code null}
* @throws IndexOutOfBoundsException If {@code off} is negative, {@code len}
* is negative, or {@code len} is greater than {@code b.length -
off}
*
* @since 1.9
*/
public int readNBytes(byte[] b, int off, int len) throws IOException {
Objects.requireNonNull(b);
if (off < 0 || len < 0 || len > b.length - off)
throw new IndexOutOfBoundsException();
int n = 0;
while (n < len) {
int count = read(b, off + n, len - n);
if (count < 0)
break;
n += count;
}
return n;
}
