BufferedReader ready method in a while loop to determine EOF?
I have a large file (English Wi开发者_Go百科kipedia articles only database as XML files). I am reading one character at a time using BufferedReader
. The pseudocode is:
file = BufferedReader...
while (file.ready())
character = file.read()
Is this actually valid? Or will ready
just return false
when it is waiting for the HDD to return data and not actually when the EOF
has been reached? I tried to use if (file.read() == -1)
but seemed to run into an infinite loop that I literally could not find.
I am just wondering if it is reading the whole file as my statistics say 444,380 Wikipedia pages have been read but I thought there were many more articles.
The Reader.ready()
method is not intended to be used to test for end of file. Rather, it is a way to test whether calling read()
will block.
The correct way to detect that you have reached EOF is to examine the result of a read
call.
For example, if you are reading a character at a time, the read()
method returns an int
which will either be a valid character or -1
if you've reached the end-of-file. Thus, your code should look like this:
int character;
while ((character = file.read()) != -1) {
...
}
This is not guaranteed to read the whole input. ready()
just tells you if the underlying stream has some content ready. If it is abstracting over a network socket or file, for example, it could mean that there isn't any buffered data available yet.
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