Need help with efficient memory use

bulkhead

I believe this line of code is what gives me the out of memory error when it is run for about 10 seconds. I think it's something to do with my method of converting the int to a string to be written on the serial LCD. Is there a better way to do this?

public static void checkUltrasonic()
  {
    LCD.clearScr();
    LCD.write("US: ");
    LCD.write(ultrasonicSensor.getCm()+"");

  }

Jon Keinath

Do you need to have a +"" in the last line? The combination (+) of two strings causes the memory error.

bulkhead

Well, if I just do LCD.write(int) it will write an int command to the lcd, not print an int on the screen. I have added more of these statements throughout my program (printing int values) and it runs out of memory even sooner now. How else can I convert the int to a string?

Jon Keinath

There are a couple different ways -
First the string buffer

static StringBuffer buff = new StringBuffer(2); //2 = length of buffer
.
.
.
//then in the program
buff.clear();
buff.append(variable); //int (or other) variable
buff.append("Some text");
LCD.write(buff);

I don't know if the LCD class you are using has a method for write(stringBuffer), if not, I can dig out the code from the class I wrote for the LCD I normally use.


or you can use the format class available below.

groups.yahoo.com/group/JavelinCode/files/Javelin%20Stamp%20IDE/lib/stamp/util/text/

I usually use the buffer when converting ints to strings, and the format class for more complex formating tasks.

Post Edited (Jon Keinath) : 8/8/2006 2:53:24 AM GMT

bulkhead

Forgot about StringBuffers, I just tried it out and it worked great! They make such a big difference in memory usage when compared with strings. THe parallax LCD class I was using already had a write(StringBuffer) method so it worked fine. Thanks.

Peter Verkaik

If you need to format your output (for example: a value 000 to 999)
then the format class does it all in a single statement

char[noparse]/noparse buf = new char[noparse][[/noparse]10]; //textbuffer, select appropiate size

Format.sprintf(buf,"US: %03d",ultrasonicSensor.getCm());
LCD.write(buf);

All you need to know·is that buf·holds a null terminated string (aka ASCIIZ).
So you need a method LCD.write(char[noparse]/noparse s) in your lcd class

void write(char[noparse]/noparse s) {
· int i=0;
· while (s[noparse][[/noparse]i]!=0) write(s[noparse][[/noparse]i++]); //call the write(char c) method for each char
}

regards peter