nullpointer exception, tutorial sketch won't run

vrtxt

Pretty much as title says, trying to run the object tutorial for python mode, but even after correcting indentation the sketch won't run and gives a nullpointer. EDIT removed picture, see sketch code & error message below.

Hopefully someone can tell me what's going on and how to fix it. Thanks!

GoToLoop

Avoid code screenshots! Read below how to post them in this forum via markup: L-)
https://Forum.Processing.org/two/discussion/15473/readme-how-to-format-code-and-text

... even after correcting indentation...

Any1 can see your code isn't properly indented at that code screenshot! 8-|
Also, where is the rest of its class block? :-\"

vrtxt

Oh my bad, thought code wouldn't be necessary. Also, by properly indented I mean there're no more errors which say 'this line probably needs to be indented'. At any rate here's the code:

# Even though there are multiple objects, we still only need one class.
# No matter how many cookies we make, only one cookie cutter is needed.
class Car(object):
# The Constructor is defined with arguments.

    def __init__(self, c, xpos, ypos, xspeed):
        self.c = c
        self.xpos = xpos
        self.ypos = ypos
        self.xspeed = xspeed

        def display(self):
            stroke(0)
        fill(self.c)
        rectMode(CENTER)
        rect(self.xpos, self.ypos, 20, 10)

        def drive(self):
            self.xpos = self.xpos + self.xspeed
            if self.xpos > width:
                self.xpos = 0

myCar1 = Car(color(255, 0, 0), 0, 100, 2)
myCar2 = Car(color(0, 255, 255), 0, 10, 1)

def setup():
    size(200, 200)

def draw():
    background(255)
    myCar1.drive()
    myCar1.display()
    myCar2.drive()
    myCar2.display()

And here's the error message:

processing.app.SketchException: java.lang.NullPointerException
    at processing.core.PApplet.fill(PApplet.java:14465)
    at jycessing.PAppletJythonDriver.fill(PAppletJythonDriver.java:816)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:186)
    at org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:204)
    at org.python.core.PyObject.__call__(PyObject.java:478)
    at org.python.core.PyObject.__call__(PyObject.java:482)
    at org.python.core.PyMethod.__call__(PyMethod.java:141)
    at org.python.pycode._pyx44.__init__$2(python.pyde:18)
    at org.python.pycode._pyx44.call_function(python.pyde)
    at org.python.core.PyTableCode.call(PyTableCode.java:167)
    at org.python.core.PyBaseCode.call(PyBaseCode.java:307)
    at org.python.core.PyBaseCode.call(PyBaseCode.java:198)
    at org.python.core.PyFunction.__call__(PyFunction.java:482)
    at org.python.core.PyMethod.instancemethod___call__(PyMethod.java:237)
    at org.python.core.PyMethod.__call__(PyMethod.java:228)
    at org.python.core.PyMethod.__call__(PyMethod.java:223)
    at org.python.core.Deriveds.dispatch__init__(Deriveds.java:19)
    at org.python.core.PyObjectDerived.dispatch__init__(PyObjectDerived.java:1112)
    at org.python.core.PyType.type___call__(PyType.java:1713)
    at org.python.core.PyType.__call__(PyType.java:1696)
    at org.python.core.PyObject.__call__(PyObject.java:515)
    at org.python.core.PyObject.__call__(PyObject.java:521)
    at org.python.pycode._pyx44.f$0(python.pyde:1)
    at org.python.pycode._pyx44.call_function(python.pyde)
    at org.python.core.PyTableCode.call(PyTableCode.java:167)
    at org.python.core.PyCode.call(PyCode.java:18)
    at org.python.core.Py.runCode(Py.java:1386)
    at org.python.core.Py.exec(Py.java:1430)
    at org.python.pycode._pyx43.f$0(C:\Users\myName\AppData\Local\Temp\python2118232332312181385\python.pyde:89)
    at org.python.pycode._pyx43.call_function(C:\Users\myName\AppData\Local\Temp\python2118232332312181385\python.pyde)
    at org.python.core.PyTableCode.call(PyTableCode.java:167)
    at org.python.core.PyCode.call(PyCode.java:18)
    at org.python.core.Py.runCode(Py.java:1386)
    at org.python.core.Py.exec(Py.java:1430)
    at org.python.util.PythonInterpreter.exec(PythonInterpreter.java:276)
    at jycessing.PAppletJythonDriver.processSketch(PAppletJythonDriver.java:194)
    at jycessing.PAppletJythonDriver.findSketchMethods(PAppletJythonDriver.java:446)
    at jycessing.Runner.runSketchBlocking(Runner.java:385)
    at jycessing.mode.run.SketchRunner$3.run(SketchRunner.java:118)
    at java.lang.Thread.run(Thread.java:748)

    at jycessing.mode.run.SketchRunner.convertPythonSketchError(SketchRunner.java:230)
    at jycessing.mode.run.SketchRunner.access$4(SketchRunner.java:227)
    at jycessing.mode.run.SketchRunner$3.run(SketchRunner.java:122)
    at java.lang.Thread.run(Thread.java:748)

GoToLoop

In method display() below, clearly only the stroke(0) statement is correctly indented in relation to its method. The other 3 statements are outside method display(): #-o

def display(self):
    stroke(0)
fill(self.c)
rectMode(CENTER)
rect(self.xpos, self.ypos, 20, 10)

Solution, indent the other 3 statements as well: ;;)

def display(self):
    stroke(0)
    fill(self.c)
    rectMode(CENTER)
    rect(self.xpos, self.ypos, 20, 10)

GoToLoop

2nd bug, in class Car, only the __init__() constructor method is indented in relation to its class.
The other 2 methods are indented in relation to __init__() instead of their class! @-)

class Car(object):
    def __init__(self, c, xpos, ypos, xspeed):
        self.c = c
        self.xpos = xpos
        self.ypos = ypos
        self.xspeed = xspeed

        def display(self):
            stroke(0)
            fill(self.c)
            rectMode(CENTER)
            rect(self.xpos, self.ypos, 20, 10)

        def drive(self):
            self.xpos = self.xpos + self.xspeed
            if self.xpos > width:
                self.xpos = 0

Solution, make all def aligned, so they're all indented in relation to class Car. B-)

Extra æsthetic tip, skip 2 lines after each def block. And 3 for each class block: :bz

class Car(object):
    def __init__(self, c, xpos, ypos, xspeed):
        self.c = c
        self.xpos = xpos
        self.ypos = ypos
        self.xspeed = xspeed


    def display(self):
        stroke(0)
        fill(self.c)
        rectMode(CENTER)
        rect(self.xpos, self.ypos, 20, 10)


    def drive(self):
        self.xpos = self.xpos + self.xspeed

        if self.xpos > width:
            self.xpos = 0



myCar1 = Car(color(255, 0, 0), 0, 100, 2)
myCar2 = Car(color(0, 255, 255), 0, 10, 1)

vrtxt

thanks a bunch! Apparently the error 'this line _probably _need to be indented' isn't all that helpful then? And admittedly I got annoyed by it. :-S :D

Thanks again!