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Java Socket - how does the read () method know if the end of the stream has been reached?

  • How does InputStream.read (byte []) know if "end of stream" has been reached and "-1" is returned?

  • What are all the conditions for a "-1" return?

  • How do I detect the "end of stream" (without sending an integer that contains the total number of bytes read previously)?

Usage example:

InputStream input = socket.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
for(int size = -1; (size = input.read(buffer)) != -1; ) {
    baos.write(buffer, 0, size);
}
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1 answer


InputStream

is an abstract type with many implementations. A FileInputStream

, for example, will return -1

if you have reached the end of the file. If it is a TCP socket, it will return -1 if the connection was closed. It is implementation dependent how the final stream is defined.



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