NullPointerException hhhmmmmm

Programming Questions

fuzzymurd..

NullPointerException hhhmmmmm

in Programming Questions • 2 years ago

Hi ...

I have my arduino uno that transmit ( Serial.println) every 100ms. The i have my processing program where i want to

readout the serial value in a line lenght. When i add the convesion from string to float (line) in the program i get a

NullPointerException. The serial communication when works fine if i just text("" + inString,10,50) but what

i add float a = float(inString); i got this NullPointer.......thing... why????

 import processing.serial.*; Serial myPort; // The serial port: String inString; // Input string from serial port: int lf = 10; // ASCII linefeed void setup() { size(400,200); myPort = new Serial(this, Serial.list()[0], 9600); myPort.bufferUntil(lf); } void draw() { background(0); text("received: " + inString, 10,50); Works fine with this alone

  //float a = float(inString);             make the NullPointerExeception WHY??????

 } void serialEvent(Serial p) { inString = p.readString(); }

Regards Fuzz

Replies(1)

quarks

Re: NullPointerException hhhmmmmm

2 years ago

First it returns null bcause inString is null and you need to test for this before attempting to use inString.

I assume that you are trying to convert inString to a float but your syntax will not work. This code should do what you want.

void draw() {
background(0);
float a;
text("received: " + inString, 10,50);
if(inString != null) {
try {
a = Float.parseFloat(inString);
}
catch(NumberFormatException excp) {
a = 0;
System.out.println("Invalid float");
}
}
}