Null Pointer Exceptions problem in processing ide

Using Arduino Programming Questions
1

hello hi, sorry am trying to get data from arduino through serial port to processing ide but a getting an error that say Null Pointer Exceptions. below is my full processing code.



// Import Meter library
import meter.*;

// Import serial library
import processing.serial.*;

Serial serial_port = null;        // the serial port

// serial port buttons
Button btn_serial_up;              // move up through the serial port list
Button btn_serial_dn;              // move down through the serial port list
Button btn_serial_connect;         // connect to the selected serial port
Button btn_serial_disconnect;      // disconnect from the serial port
Button btn_serial_list_refresh;    // refresh the serial port list
String serial_list;                // list of serial ports
int serial_list_index = 0;         // currently selected serial port 
int num_serial_ports = 0;          // number of serial ports in the list

PImage img;

Meter m, m2, m3, m4, m5, m6, m7, m8;

void setup(){
  // First we need to create a empty window
  size(1860, 800); // Size of the window (width, height)
  background(10, 10, 82); // Background color of window (R,G,B)
  
 // create the buttons
  btn_serial_up = new Button("^", 140, 730, 40, 20);
  btn_serial_dn = new Button("v", 140, 690, 40, 20);
  btn_serial_connect = new Button("Connect", 190, 670, 100, 25);
  btn_serial_disconnect = new Button("Disconnect", 190, 710, 100, 25);
  btn_serial_list_refresh = new Button("Refresh", 190, 750, 100, 25);
  
  // get the list of serial ports on the computer
  serial_list = Serial.list()[serial_list_index];
  
  //println(Serial.list());
  //println(Serial.list().length);
  
  // get the number of serial ports in the list
  num_serial_ports = Serial.list().length;
  
 
  // TANK 1
  
  m = new Meter(this, 10, 51);  // here 25, 10 are x and y coordinates of meter's upper left corner
  
  m.setTitleFontSize(20);
  m.setTitleFontName("Arial bold");
  m.setTitle("TANK 1 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m.setScaleLabels(scaleLabels);
  m.setScaleFontSize(18);
  m.setScaleFontName("Times new roman bold");
  m.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m.setArcColor(color(141, 113, 178));
  m.setArcThickness(15);
  
  m.setMaxScaleValue(100);
  
  m.setMinInputSignal(0);
  m.setMaxInputSignal(100);
  
  m.setNeedleThickness(3);
  
  // TANK 2
  // lets take some refference from first meter
  int mx = m.getMeterX(); // x coordinate of m
  int my = m.getMeterY(); // y coordinate of m
  int mw = m.getMeterWidth();
  
  m2 = new Meter(this, mx + mw + 20, my);
  
  m2.setTitleFontSize(20);
  m2.setTitleFontName("Arial bold");
  m2.setTitle("TANK 2 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels2 = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m2.setScaleLabels(scaleLabels2);
  m2.setScaleFontSize(18);
  m2.setScaleFontName("Times new roman bold");
  m2.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m2.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m2.setArcColor(color(141, 113, 178));
  m2.setArcThickness(15);
  
  m2.setMaxScaleValue(100);
  
  m2.setMinInputSignal(0);
  m2.setMaxInputSignal(100);
  
  m2.setNeedleThickness(3);
  
  ////WATER TANK 3

  // lets take some refference from first meter
  int mx1 = m.getMeterX(); // x coordinate of m
  int my1 = m.getMeterY(); // y coordinate of m
  int mw1 = m.getMeterWidth();
  
  //m3 = new Meter(this, 250, 400);
   m3 = new Meter(this, mx + mw + 490, my);
  
  m3.setTitleFontSize(20);
  m3.setTitleFontName("Arial bold");
  m3.setTitle("TANK 3 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels3 = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m3.setScaleLabels(scaleLabels3);
  m3.setScaleFontSize(18);
  m3.setScaleFontName("Times new roman bold");
  m3.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m3.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m3.setArcColor(color(141, 113, 178));
  m3.setArcThickness(15);
  
  m3.setMaxScaleValue(100);
  
  m3.setMinInputSignal(0);
  m3.setMaxInputSignal(100);
  
  m3.setNeedleThickness(3);
  
  
   ////WATER TANK 4

  // lets take some refference from first meter
  int mx2 = m.getMeterX(); // x coordinate of m
  int my2 = m.getMeterY(); // y coordinate of m
  int mw2 = m.getMeterWidth();
  
  //m3 = new Meter(this, 250, 400);
   m4 = new Meter(this, mx + mw + 950, my);
  
  m4.setTitleFontSize(20);
  m4.setTitleFontName("Arial bold");
  m4.setTitle("TANK 4 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels4 = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m4.setScaleLabels(scaleLabels4);
  m4.setScaleFontSize(18);
  m4.setScaleFontName("Times new roman bold");
  m4.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m4.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m4.setArcColor(color(141, 113, 178));
  m4.setArcThickness(15);
  
  m4.setMaxScaleValue(100);
  
  m4.setMinInputSignal(0);
  m4.setMaxInputSignal(100);
  
  m4.setNeedleThickness(3);
  
  
  
  // TANK 5
  
  m5 = new Meter(this, 10, 380);  // here 25, 10 are x and y coordinates of meter's upper left corner
  
  m5.setTitleFontSize(20);
  m5.setTitleFontName("Arial bold");
  m5.setTitle("TANK 5 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels5 = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m5.setScaleLabels(scaleLabels5);
  m5.setScaleFontSize(18);
  m5.setScaleFontName("Times new roman bold");
  m5.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m5.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m5.setArcColor(color(141, 113, 178));
  m5.setArcThickness(15);
  
  m5.setMaxScaleValue(100);
  
  m5.setMinInputSignal(0);
  m5.setMaxInputSignal(100);
  
  m5.setNeedleThickness(3);
  
  
   // TANK 6
  // lets take some refference from first meter
  int mx3 = m.getMeterX(); // x coordinate of m
  int my3 = m.getMeterY(); // y coordinate of m
  int mw3 = m.getMeterWidth();
  
   m6 = new Meter(this, 470, 380);  // here 25, 10 are x and y coordinates of meter's upper left corner
  
  m6.setTitleFontSize(20);
  m6.setTitleFontName("Arial bold");
  m6.setTitle("TANK 6 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels6 = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m6.setScaleLabels(scaleLabels6);
  m6.setScaleFontSize(18);
  m6.setScaleFontName("Times new roman bold");
  m6.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m6.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m6.setArcColor(color(141, 113, 178));
  m6.setArcThickness(15);
  
  m6.setMaxScaleValue(100);
  
  m6.setMinInputSignal(0);
  m6.setMaxInputSignal(100);
  
  m6.setNeedleThickness(3);
  
  
  
  // TANK 7
  // lets take some refference from first meter
  int mx4 = m.getMeterX(); // x coordinate of m
  int my4 = m.getMeterY(); // y coordinate of m
  int mw4 = m.getMeterWidth();
  
   m7 = new Meter(this, 941, 380);  // here 25, 10 are x and y coordinates of meter's upper left corner
  
  m7.setTitleFontSize(20);
  m7.setTitleFontName("Arial bold");
  m7.setTitle("TANK 7 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels7 = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m7.setScaleLabels(scaleLabels7);
  m7.setScaleFontSize(18);
  m7.setScaleFontName("Times new roman bold");
  m7.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m7.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m7.setArcColor(color(141, 113, 178));
  m7.setArcThickness(15);
  
  m7.setMaxScaleValue(100);
  
  m7.setMinInputSignal(0);
  m7.setMaxInputSignal(100);
  
  m7.setNeedleThickness(3);
  
  
  
  // TANK 8
  // lets take some refference from first meter
  int mx5 = m.getMeterX(); // x coordinate of m
  int my5 = m.getMeterY(); // y coordinate of m
  int mw5 = m.getMeterWidth();
  
   m8 = new Meter(this, 1400, 380);  // here 25, 10 are x and y coordinates of meter's upper left corner
  
  m8.setTitleFontSize(20);
  m8.setTitleFontName("Arial bold");
  m8.setTitle("TANK 8 WATER LEVEL(%)");
  
  // Change meter scale values
  String[] scaleLabels8 = {"0", "10", "20", "30", "40", "50", "60", "70", "80", "90", "100"};
  m8.setScaleLabels(scaleLabels8);
  m8.setScaleFontSize(18);
  m8.setScaleFontName("Times new roman bold");
  m8.setScaleFontColor(color(200, 30, 70));
  
  // We can also display the value of meter
  m8.setDisplayDigitalMeterValue(true);
  
  // Lets do some more modifications so our meter looks nice
  m8.setArcColor(color(141, 113, 178));
  m8.setArcThickness(15);
  
  m8.setMaxScaleValue(100);
  
  m8.setMinInputSignal(0);
  m8.setMaxInputSignal(100);
  
  m8.setNeedleThickness(3);
  
}


void mousePressed() {
  // up button clicked
  if (btn_serial_up.MouseIsOver()) {
    if (serial_list_index > 0) {
      // move one position up in the list of serial ports
      serial_list_index--;
      serial_list = Serial.list()[serial_list_index];
    }
  }
  // down button clicked
  if (btn_serial_dn.MouseIsOver()) {
    if (serial_list_index < (num_serial_ports - 1)) {
      // move one position down in the list of serial ports
      serial_list_index++;
      serial_list = Serial.list()[serial_list_index];
    }
  }
  // Connect button clicked
  if (btn_serial_connect.MouseIsOver()) {
    if (serial_port == null) {
      // connect to the selected serial port
      serial_port = new Serial(this, Serial.list()[serial_list_index], 9600);
    }
  }
  // Disconnect button clicked
  if (btn_serial_disconnect.MouseIsOver()) {
    if (serial_port != null) {
      // disconnect from the serial port
      serial_port.stop();
      serial_port = null;
    }
  }
  // Refresh button clicked
  if (btn_serial_list_refresh.MouseIsOver()) {
    // get the serial port list and length of the list
    serial_list = Serial.list()[serial_list_index];
    num_serial_ports = Serial.list().length;
  }
}

void draw(){
  
  
   if (serial_port.available()> 0){
    String val = serial_port.readString(); // read incoming string on serial port
    // First we need to separate  values
    String[] list = split(val, ','); // splits value separated by ','
    int tank_1 = int(list[0]); // Tank1
    int tank_2 = int(list[1]);  // Tank2
    int tank_3 = int(list[2]);  //  Tank3
    int tank_4 = int(list[3]);  // Tank4
    int tank_5 = int(list[4]);  // Tank5
    int tank_6 = int(list[5]);  // Tank6
    int tank_7 = int(list[6]);  // Tank7
    int tank_8 = int(list[7]);  // Tank8
    m.updateMeter(int(tank_1)); // int is used due to updateMeter accepts only int values
    m2.updateMeter(int(tank_2));
    m3.updateMeter(int(tank_3));
    m4.updateMeter(int(tank_4));
    m5.updateMeter(int(tank_5));
    m6.updateMeter(int(tank_6));
    m7.updateMeter(int(tank_7));
    m8.updateMeter(int(tank_8));
    println("Water Tank 1 Level: " + tank_1 + " %  " + "Water Tank 2 Level: " + tank_2+ "%"+"Water Tank 3 Level: "+tank_3+ "%"+"Water Tank 4 Level: "+tank_4+ "%"+"Water Tank 5 Level: "+tank_5+ "%" +"Water Tank 6 Level: "+tank_6+ "%"+"Water Tank 7 Level: "+tank_7+ "%"+"Water Tank 8 Level: "+tank_8+ "%");
  }
  
   // draw the buttons in the application window
  btn_serial_up.Draw();
  btn_serial_dn.Draw();
  btn_serial_connect.Draw();
  btn_serial_disconnect.Draw();
  btn_serial_list_refresh.Draw();
  // draw the text box containing the selected serial port
  DrawTextBox("Select Port", serial_list, 10, 690, 120, 60);
}

// function for drawing a text box with title and contents
void DrawTextBox(String title, String str, int x, int y, int w, int h)
{
  fill(255);
  rect(x, y, w, h);
  fill(0);
  textAlign(LEFT);
  textSize(14);
  text(title, x + 10, y + 10, w - 20, 20);
  textSize(12);  
  text(str, x + 10, y + 40, w - 20, h - 10);
}

// button class used for all buttons
class Button {
  String label;
  float x;    // top left corner x position
  float y;    // top left corner y position
  float w;    // width of button
  float h;    // height of button
  
  // constructor
  Button(String labelB, float xpos, float ypos, float widthB, float heightB) {
    label = labelB;
    x = xpos;
    y = ypos;
    w = widthB;
    h = heightB;
  }
  
  // draw the button in the window
  void Draw() {
    fill(218);
    stroke(141);
    rect(x, y, w, h, 10);
    textAlign(CENTER, CENTER);
    fill(0);
    text(label, x + (w / 2), y + (h / 2));
  }
  
  // returns true if the mouse cursor is over the button
  boolean MouseIsOver() {
    if (mouseX > x && mouseX < (x + w) && mouseY > y && mouseY < (y + h)) {
      return true;
    }
    return false;
  }
}
2

This would be a question for the Processing forum…

3

ok, can you direct me to that forum sir

4

I suppose that Google is broken where you live…

The typical way to open the serial port is described here

https://processing.org/reference/libraries/serial/Serial.html

As for the arduino forum they have best practices for posting, read this with the required attention

5

still i can not resolve it sir

6

just a guess:

in draw, when you first run

➜ serial_port is null so you can't call available()

change it to

   if (serial_port != null && serial_port.available()> 0){
7

thank you so much sir it works, god bless you sir

8

have fun!

9

thanks

10

then sorry sir do you know how to change specific text size in processing ide without affecting other text?

11

I'm not sure if you mean the font for the IDE or your application... if this is for the IDE, then you can do that in the preference panel. if this is for the application, you need to read the code, you'll see code dealing with fonts such as

  m.setTitleFontSize(20);
  m.setTitleFontName("Arial bold");

But as I said above, this is the Arduino forum here, not the processing forum. I suggest you take your questions there.

12

ok sorry i mean the size of the specific text on the application form

13

then that's the latter. read the code, looking for the Font word in functions .

14

ok sir

15

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