[ACCEPTED]-What 0 returned by InputStream.read() means? How to handle this?-inputstream
The only situation in which a
InputStream may return 10
0 from a call to
read(byte) is when the
byte passed in 9 has a length of 0:
byte buf = new byte; int read = in.read(buf); // read will contain 0
As specified by this part 8 of the JavaDoc:
If the length of b is zero, then 7 no bytes are read and 0 is returned
My guess: you 6 used
available() to see how big the buffer should be 5 and it returned
0. Note that this is a misuse 4 of
available(). The JavaDoc explicitly states that:
It 3 is never correct to use the return value 2 of this method to allocate a buffer intended 1 to hold all data in this stream.
Take a look at the implementation of javax.sound.AudioInputStream#read(byte b, int 10 off, int len) ... yuck. They completely 9 violated the standard java.io.InputStream 8 semantics and return a read size of 0 if 7 you request fewer than a whole frame of 6 data.
So unfortunately; the common advice 5 (and api spec) should preclude having to 4 deal with return of zero when len > 0 but 3 even for JDK provided classes you can't 2 universally rely on this to be true for 1 InputStreams of arbitrary types.
According to Java API Doc:
It only can happen 6 if the byte you passed has zero items 5 (new byte).
In other situations it must 4 return at least one byte. Or -1 if EOF reached. Or 3 an exception.
Of course: it depends of the actual implementation 2 of the InputStream you are using!!! (it 1 could be a wrong one)
I observed the same behavior (reading 0 3 bytes) when I build a swing console output 2 window and made a reader-thread for stdout 1 and stderr via the following code:
When the 'main' swing application exits, and my console window is still open I read 0 from this.pi.read(). The read data was put on the console window resulting in a race condition some how, just ignoring the result and not updating the console window solved the issue.
this.pi = new PipedInputStream(); po = new PipedOutputStream((PipedInputStream)pi); System.setOut(new PrintStream(po, true));
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