null pointer exception problem (scope problems)

mel_

Hi, I'm trying to export from a csv file. I've done it once with the destinations variable but the distance one I am doing the exact same thing as the working destinations but comes up as a null pointer exception even though i have created global variables for it.

int sWidth = 1000;
int sHeight = 600;
IButton btn1;
IImageButton btn2;
IImageButton btn3;
color rectangleCol;
boolean isTiming;
int savedTimer;
int elapsedTime;
int y;
PImage second;
PImage bg;
PImage img1;
PImage img2;
PImage img3;
PImage img4;
PImage img5;
PImage img6;
PImage img7;
PImage img8;
PImage img9;
String currentScreen = "start";
String[] IBtnImages = {
  "buttonone.jpg", "buttontwo.jpg", "stop2.jpg"
};
String[] ImageBtnImages = {
  "map.jpg", "maprollover.jpg", "mapbuttonclick.jpg", "home.jpg", "returnrollover.jpg", "returnpressed.jpg"
};
String buttonPressedID = "none";
Table table;
int checkThisNumber = elapsedTime*500;
int xCoord;
int yCoord;
String destination;
String distance;
boolean hasResult = false;
StringList destinations;
StringList distances;
IntList xCoords;
IntList yCoords;
PFont font;
PFont font2;






void setup() {

  destinations = new StringList();
  distances = new StringList();
  xCoords = new IntList();
  yCoords = new IntList();



  table = loadTable("xy2.csv", "header");

  println(table.getRowCount() + " total rows in table"); 

  for (TableRow row : table.rows()) {

    int destination = row.getInt("destination");
    int distance = row.getInt("distance");
    String x = row.getString("x");
    String y = row.getString("y");
    String elapsedtime = row.getString("elapsedtime");

  }

  img1 = loadImage(ImageBtnImages[0]);
  img2 = loadImage(ImageBtnImages[1]);
  img3 = loadImage(ImageBtnImages[2]);
  img4 = loadImage(ImageBtnImages[3]);
  img5 = loadImage(ImageBtnImages[4]);
  img6 = loadImage(ImageBtnImages[5]);

  img7 = loadImage(IBtnImages[0]);
  img8 = loadImage(IBtnImages[1]);
  img9 = loadImage(IBtnImages[2]);

  font = loadFont("Dia-40.vlw");
  font2 = loadFont("font2-14.vlw");


  size(sWidth, sHeight);

  btn1 = new IButton("button 1", 187, 360, img7, img8, img9);

  btn2 = new IImageButton("button 2", 800, 10, img1, img2, img3);
  btn3 = new IImageButton("button 3", 20, 15, img4, img5, img6);


  bg = loadImage("timepiecehomescreen.jpg");
  second = loadImage("timepiecemap.jpg");
}

void draw() {

  if (currentScreen == "start") {
    background(bg);


    btn1.update();
    btn2.update();
  } 
  else if (currentScreen == "second") {

    background(second);


    if (hasResult == true) {
      println(xCoord+" : "+yCoord);
      stroke(255, 31, 188);
      line(445, 510, xCoord, yCoord);

      textFont(font2, 14);
      text(destination, xCoord, yCoord);
      fill(211, 68, 169);

      textFont(font, 40);
      text("WELCOME TO...", 350, 50);
      fill(211, 68, 169);

      textFont(font2, 25);
      text("Distance travelled...", 380, 85);
      fill(211, 68, 169);

      textFont(font2, 25);
      text(distance, 610, 85);
      fill(211, 68, 169);

    } 
    else {
      //show record of destinations
      for (int i=0; i<destinations.size(); i++) {

        String dest = destinations.get(i);

        int xCo = xCoords.get(i);
        int yCo = yCoords.get(i);

      stroke(255, 31, 188);

        line(445, 510, xCo, yCo);

        textFont(font2, 14);
        text(dest, xCo, yCo);
        fill(211, 68, 169);

        textFont(font, 40);
        text("TRAVEL HISTORY", 350, 50);
        fill(211, 68, 169);

      }


    }

    btn3.update();
  }
}

void mousePressed() {

  if (btn1.mPressed()) {
    buttonPressedID = btn1.getID();



    if (isTiming = !isTiming) {
      savedTimer = millis();
      println("Current Time: " + savedTimer/1000 + "s.");
    }

    else {
      elapsedTime = (millis() - savedTimer) / 1000;
      println("Elapsed Time: " + elapsedTime + "s.\n");

      int checkThisNumber = elapsedTime*500;
      //boolean hasResult1 = true;    

      for (int check=checkThisNumber;check>0;check-=500) {

        TableRow result1 = table.findRow(str(check), "elapsedtime");
        println(check);

        if (result1 == null) {
          hasResult = false;
        } 
        else {
          xCoord = result1.getInt("x");
          yCoord = result1.getInt("y");
          destination = result1.getString("destination");
          hasResult = true;
          destinations.append(destination);
          xCoords.append(xCoord);
          yCoords.append(yCoord);
          break;
        }
      }

      println(hasResult);

      if (hasResult == true) {
        currentScreen = "second";
      }
    }
  }



  if (btn2.mPressed()) {
    buttonPressedID = btn2.getID();
    hasResult = false;
    currentScreen = "second";
  }

  if (btn3.mPressed()) {
    buttonPressedID = btn3.getID();

    currentScreen = "start";
  }
}


void mouseReleased() {

  btn1.mReleased(); 
  btn2.mReleased();
  btn3.mReleased();
}

koogs

please post the stack trace and the line number of the error as seen in the console when you run it

(we can't run your code - we have none of the data files, images or extra classes)

koogs

(is there a FAQ on how to ask questions? maybe there needs to be. and a link to it from forum pages...)

mel_

sorry its 131!!!

koogs

where are you setting distance?

koogs

(you aren't)

PhiLho

int sWidth = 1000; int sHeight = 600;

These duplicate the functionality of the built-in variables width and height. Just call size(1000, 600); and uses these variables. Move the call to size() to the start of setup(), as said in the reference...

int checkThisNumber = elapsedTime*500;

There, elapsedTime is still zero, to checkThisNumber will be zero...

See also the article From several variables to arrays, always recommended when we see img1, img5, etc.

mel_

I set the distance in the global variables at the top (35) and in draw (65).

(and as for the size thing, i realise that but our teacher prefers it to be the way we have done it)

PhiLho

distance is an int, so it cannot be null (can be zero, at worst). So I am surprised to see a NPE at this line. Are you sure that's the highlighted line when you get the exception? Can you show the stack trace, as asked?

mel_

Thats what i was thinking!!! Yes its definately that line highlighted. I don't know what a stack trace is but I'm assuming its the text in the black box under the code? (sorry i must sound like such an idiot!) that just says:

40 total rows in table Current Time: 2s. Elapsed Time: 14s.

7000 6500 true 459 : 499

i have zero clue whats going on!!!

koogs

distance on line 35 is defined as a String but isn't set to anything, therefore is null.

the distance you set on line 65 is another variable called distance, an int and local to that block of code - it's an entirely different variable because of the usual scope rules and is hiding the global String.

in the text() it's trying to use the global version, which is still null.

mel_

i've figured it out! it needs to be set at 193! thanks for your help!