StringBuffer and CharBuffer

Question

Hello,
I just stumled across some weird behaviour. It seems to be impossible to directly create a StringBuffer from a CharBuffer.
Consider the following code:
FileReader reader = new FileReader(fileName);
CharBuffer chars = CharBuffer.allocate((int) fileSize);
// read complete file
while(reader.read(chars) != 0);
reader.close();
StringBuffer sb = new StringBuffer(chars);This will result in an empty StringBuffer. The reason for this is that StringBuffer uses CharSequence.length() to determine the length of the CharBuffer. However, CharBuffer implements the length method so that it returns the number of remaining bytes, not the bytes already written to the buffer!!! In the example above, the remaining bytes are 0. A work around for this problem is to call
chars.position(0);before creating the StringBuffer. While this is would work in this case, it might not always be a solution.
Is this a broken behaviour on behalf of CharBuffer? I mean it implements the CharSequence interface and thus should also behave like a CharSequence. IMHO, the CharBuffer implementation of the length method plainly contradicts the defintion of CharSequence.length().
Any comments?
Thank you very much
draoi

Answer 1

FileReader reader = new FileReader(fileName);
CharBuffer chars = CharBuffer.allocate((int)
fileSize);
// read complete file
while(reader.read(chars) != 0);
reader.close();
StringBuffer sb = new StringBuffer(chars);This will result in an empty StringBuffer. The reasonHow about using chars.flip() just before creating the StringBuffer. Seems to work for me (but used put instead of read).
Harald.
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