Could anyone tell me what happens in this method?
I have a method that does a few things that I would like to know what it is...just explain it to me over the top, please?
private static byte[] readFully(InputStream in) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
for (int count; (count = in.read(buffer)) != -1; ) {
out.write(buffer, 0, count);
}
return out.toByteArray();
}
1 answers
The method in question is reading the entire contents of an input stream (e.g., from a file, network port, etc.) to an array of bytes in memory.
The ByteArrayOutputStream is an output stream that keeps everything you write (write) in memory.
The code is basicando by reading the contents of InputStream in blocks up to 1kib (1024 bytes) and writing it to ByteArrayOutputStream. This is a very manual way of buffering the operation.
Fine line out.toByteArray() returns everything that was written in ByteArrayOutputStream as a byte[].
See that there are several alternative libraries and implementations to solve this problem. Java 9 inclusive will include a new method InputStream.readAllBytes() for that purpose.