On 2/13/18, 12:41 AM, Alan Bateman wrote:

public int getBytes(byte[] dst, int offset, Charset cs);
public int getBytes(byte[] dst, int offset, String csname);
public int getBytes(ByteBuffer bytes, Charset cs);
public int getBytes(ByteBuffer bytes, Charset csn);
These four methods encode as many characters as possible into the destination byte[] or buffer but don't give any indication that the destination didn't have enough space to encode the entire string. I thus worry they could be a hazard and result in buggy code. If there is insufficient space then the user of the API doesn't know how many characters were encoded so it's not easy to substring and call getBytes again to encode the remaining characters. There is also the issue of how to size the destination. What would you think about having them fail when there is insufficient space? If they do fail then there is a side effect that they will have written to the destination so that would need to be documented too.

Well It's the old "how to control/manage the en/decoding state" issue we have to deal with for this kind of apis. I think we faced the similar issue when designing bae64 de/

A possible solution is to return negative value to indicate the buffer/byte[] provided is not big enough and its value is the length needed to de/encode the whole String. So you can pass in a zero-remaining ByteBuffer or byte[0] to ask for the size needed, or we can go even further, take a NULL, like the old C str method to return the size needed,
though I don't think we want to go that far :-)

That said one of the motivations of these APIs is to easy the use of doing de/encoding between ByteBuffer and String, the extra step to handle the "needed buffer size" appears to be against the original goal. But the api can always say "please provide big-enough buffer, otherwise the method returns the size needed in negative value and the passed
in buffer might be partially filled ..."


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