pls help to find what's wrong with my code

zhanglq

I wrote a piece of code to read serial data (hex) and turns the data to dec for future usage, the code is as follows. But there's something wrong with the line: brightness=unhex(brightnessHEX). I have no idea about it and really hope somebosy here to help me with that.

import processing.serial.*;
Serial myPort;
int brightness = 0;
PFont font;
String brightnessHEX;

void setup() {
  size(800, 600);
  smooth();

  String portName = Serial.list()[0];
  myPort = new Serial(this, portName, 9600);
  myPort.bufferUntil('\n');
}

void draw() {
  background(0);

  while (myPort.available () > 0) {
    brightnessHEX = myPort.readStringUntil('\n');
    if (brightnessHEX != null) {
      println(brightnessHEX);
      brightness=unhex(brightnessHEX);
      println(brightness);
    }
  }
  ......
}

amnon

Add this line before you unhex(): brightnessHEX = brightnessHEX.replaceAll("\n", "");

zhanglq

thanks amnon very much, I changed the code as you suggested, but the problem is still existed there.

GoToLoop

Perhaps try out trim(): http://processing.org/reference/trim_.html
brightnessHEX = trim( myPort.readStringUntil('\n') );

or: http://docs.oracle.com/javase/8/docs/api/java/lang/String.html#trim--

brightnessHEX = myPort.readStringUntil('\n').trim();

zhanglq

thanks GoToLoop a lot! the problem get resolved with via using trim() method. the workable code is as follows.

    import processing.serial.*;
    Serial myPort;
    int brightness = 0;
    PFont font;
    String brightnessHEX;
    String brightnessHEXClean;

    void setup() {
      size(800, 600);
      smooth();

      String portName = Serial.list()[0];
      myPort = new Serial(this, portName, 9600);
      myPort.bufferUntil('\n');
    }

    void draw() {
      background(0);

      while (myPort.available () > 0) {
        brightnessHEX = myPort.readStringUntil('\n');

        if (brightnessHEX != null) {
          brightnessHEXClean = trim(brightnessHEX);//Removes whitespace characters from the beginning and end of a String
          println(brightnessHEXClean);
          brightness = unhex(brightnessHEXClean);
          println(brightness);
        }
      }
    ...
    }

koogs

it's often helpful to do this, add things before and after your string, so you can see if it is really how it looks:

println("[" + brightnessHEX + "]");

GoToLoop

Also method length() is useful to check whether the # of char values are indeed what's expected:
http://processing.org/reference/String_length_.html

zhanglq

koogs and GoToLoop, your tips are really great!