If you don't need thread synchronization, use StringBuilder instead of
StringBuffer.
R/
On Mon, May 25, 2009 at 3:47 PM, Robert Green <rbgrn....@gmail.com> wrote:
>
> The score changes every frame. I like how it works because it's tons
> of tiny increments. I actually just did the thing I talked about with
> the reusable char[]. The only caveat is that I have to allocate a new
> one when the length of the string changes, but that only happens when
> the score has changed by a factor of 10 and I don't see scores going
> over 6 digits long. I suppose it's possible someone could play the
> game forever and score much higher but it's highly unlikely.
>
> This is about as efficient as I will ever care to make such a thing.
> If you want to _never_ allocate, you could make a char[][] where the
> first dimension is the length of the second dimension arrays. That
> would be char[1], char[2], char[3], char[4] and so on. That would
> make it so that if your string size were 5 chars, you would say char[]
> correctArray = myArrays[5]. I didn't both with that because a few
> allocations are ok, just not one every tick of the loop.
>
> This is ugly but if you need something like this, it does work:
>
> I have a class called Util and I put this in it:
>
> private final static int[] intSizeTable = { 9, 99, 999, 9999, 99999,
> 999999, 9999999, 99999999, 999999999,
> Integer.MAX_VALUE };
>
> private final static char[] DigitTens = { '0', '0', '0', '0', '0',
> '0', '0', '0', '0', '0', '1', '1', '1', '1',
> '1', '1', '1', '1', '1', '1', '2', '2', '2', '2', '2',
> '2', '2',
> '2', '2', '2', '3', '3', '3', '3', '3',
> '3', '3', '3', '3', '3', '4', '4', '4', '4', '4', '4',
> '4', '4',
> '4', '4', '5', '5', '5', '5', '5', '5',
> '5', '5', '5', '5', '6', '6', '6', '6', '6', '6', '6',
> '6', '6',
> '6', '7', '7', '7', '7', '7', '7', '7',
> '7', '7', '7', '8', '8', '8', '8', '8', '8', '8', '8',
> '8', '8',
> '9', '9', '9', '9', '9', '9', '9', '9',
> '9', '9', };
>
> private final static char[] DigitOnes = { '0', '1', '2', '3', '4',
> '5', '6', '7', '8', '9', '0', '1', '2', '3',
> '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4',
> '5', '6',
> '7', '8', '9', '0', '1', '2', '3', '4',
> '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5',
> '6', '7',
> '8', '9', '0', '1', '2', '3', '4', '5',
> '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6',
> '7', '8',
> '9', '0', '1', '2', '3', '4', '5', '6',
> '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7',
> '8', '9',
> '0', '1', '2', '3', '4', '5', '6', '7',
> '8', '9', };
>
> private final static char[] digits = { '0', '1', '2', '3', '4', '5',
> '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
> 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
> 'q', 'r',
> 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
>
> // Requires positive x
> private static int stringSize(int x) {
> for (int i = 0;; i++) {
> if (x <= intSizeTable[i]) {
> return i + 1;
> }
> }
> }
>
> public static void getChars(int i, int index, char[] buf) {
> if (i == Integer.MIN_VALUE) {
> System.arraycopy("-2147483648".toCharArray(), 0, buf,
> 0,
> buf.length);
> }
> int q, r;
> int charPos = index;
> char sign = 0;
>
> if (i < 0) {
> sign = '-';
> i = -i;
> }
>
> // Generate two digits per iteration
> while (i >= 65536) {
> q = i / 100;
> // really: r = i - (q * 100);
> r = i - ((q << 6) + (q << 5) + (q << 2));
> i = q;
> buf[--charPos] = DigitOnes[r];
> buf[--charPos] = DigitTens[r];
> }
>
> // Fall thru to fast mode for smaller numbers
> // assert(i <= 65536, i);
> for (;;) {
> q = (i * 52429) >>> (16 + 3);
> r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
> buf[--charPos] = digits[r];
> i = q;
> if (i == 0)
> break;
> }
> if (sign != 0) {
> buf[--charPos] = sign;
> }
> }
>
>
> Then in my game code it looks like this (for my FPS counter):
>
> int fps = this.fps;
> int fpsStringLength = Util.getSize(fps);
> if (fpsChars.length != fpsStringLength) {
> // re-allocate
> fpsChars = new char[fpsStringLength];
> }
> char[] fpsChars = this.fpsChars;
> //copy the chars into the array
> Util.getChars(fps, fpsStringLength, fpsChars);
> StringBuffer fpsText = this.fpsText;
> fpsText.delete(0, fpsText.length());
> fpsText.append(fpsChars).append(FPS_TEXT);
> canvas.drawText(fpsText, 0, fpsText.length(),
> worldWidth - 60,
> worldHeight + INFO_HEADER_HEIGHT - 20,
> gameResources.fpsPaint);
>
>
> That is SO MUCH more code than I ever wanted there but it's
> ridiculously more efficient than it was before so I'm going to call it
> good and move on.
>
> Thanks for the help everyone!
>
> On May 25, 5:19 pm, Jason Proctor <ja...@particularplace.com> wrote:
>> i'll suggest this again :-)
>>
>> when the score changes, convert to a string then, save it away, and
>> draw that each frame. at least then, you're only doing an allocation
>> when it changes.
>>
>> good enough?
>>
>>
>>
>> >My new method doesn't have problems with concatenating but no solution
>> >so far has gotten around converting an integer into a String or
>> >CharSequence. Any time you put an integer where a String should be,
>> >java automatically uses Integer.toString(i) to build a String out of
>> >it which allocates a char[] and also makes a new String.
>>
>> >So, besides ripping out stringSize and getChars from integer and
>> >holding my own char[] for the converted int, is there a clean way to
>> >handle that without new allocations?
>>
>> >On May 25, 4:29 pm, Jason Proctor <ja...@particularplace.com> wrote:
>> >> i think Mark is saying that you could redraw the score separately
>> >> from the label, potentially saving an implicit new StringBuffer
>> >> (stuff).toString () ?
>>
>> >> if score is a number, then it will need to make a new String anyway.
>> >> but you could cache the string of the score until the score changes,
>> >> so that drawing the score becomes drawing to strings as opposed to
>> >> going through StringBuffer.
>>
>> >> hth
>>
>> >> >It's a surface view so the whole scene must be rendered every frame.
>> >> >I could put it on the background I suppose but it's simple enough to
>> >> >just redraw the text.
>>
>> >> >On May 25, 4:10 pm, Mark Murphy <mmur...@commonsware.com> wrote:
>> >> >> Robert Green wrote:
>> >> >> > I said StringBuffer but I meant "Implied" StringBuffer, you know:
>>
>> >> >> > canvas.drawText(score + POINTS_LABEL, x, y, paint);
>>
>> >> >> Why redraw POINTS_LABEL every time? Can't you rework your scoreboard
>> >> to
>> >> >> only draw that once?
>>
>> >> >> --
>> >> >> Mark Murphy (a Commons
>> >> >>Guy)http://commonsware.com|http://twitter.com/commonsguy
>>
>> >> >> Android App Developer Training:http://commonsware.com/training.html
>>
>> >> --
>> >> jason.software.particle
>>
>> --
>> jason.software.particle
> >
>
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