Basically, when running my applet I am getting the following error:

2. processing.app.debug.RunnerException: NullPointerException
3. at processing.app.Sketch.placeException(Sketch.java:1543)
4. at processing.app.debug.Runner.findException(Runner.java:583)
5. at processing.app.debug.Runner.reportException(Runner.java:558)
6. at processing.app.debug.Runner.exception(Runner.java:498)
7. at processing.app.debug.EventThread.exceptionEvent(EventThread.java:367)
8. at processing.app.debug.EventThread.handleEvent(EventThread.java:255)
9. at processing.app.debug.EventThread.run(EventThread.java:89)
10. Exception in thread "Animation Thread" java.lang.NullPointerException
11. at coursework$BarGroup.convertToFloat(coursework.java:154)
12. at coursework$BarGroup.<init>(coursework.java:123)
13. at coursework.setup(coursework.java:46)
14. at processing.core.PApplet.handleDraw(PApplet.java:1583)
15. at processing.core.PApplet.run(PApplet.java:1503)
16. at java.lang.Thread.run(Thread.java:680)

This error then highlights line 38 in the following class file:

2. import processing.xml.*;
3. 
   
4. class BarGroup
5. {
6.   XMLElement[] feed;
7.   float[]      data          = convertToFloat(feed);
8.   Bar[]        group         = new Bar[3];
9.   float        highestNumber = highestValue(data);
10.   
11.   // COnstructor
12.   BarGroup ( XMLElement[] xmlValue, int xPos)
13.   {
14.     
15.     feed = new XMLElement[xmlValue.length];
16.     feed = xmlValue;
17.     
18.     // Color, height, new height, xpos
19.     group[0] = new Bar(color(0, 055, 0), 0, map(data[0], 0, highestNumber, 0, 350), xPos);
20.     group[1] = new Bar(color(0, 120, 0), 0, map(data[1], 0, highestNumber, 0, 350), (xPos + 10));
21.     group[2] = new Bar(color(0, 255, 0), 0, map(data[2], 0, highestNumber, 0, 350), (xPos + 20));
22.     
23.   }
24.   
25.   // Show the group of Bars
26.   void display()
27.   {
28.     for (int i = 0; i < 3; i++)
29.     {
30.       group[i].display();
31.     }
32.   }
33.     
34.   // Turn the XMLElement into an Array of Floats
35.   float[] convertToFloat( XMLElement[] toConvert )
36.   {
37.     
38.     String numberOne = toConvert[0].getContent();
39.     String numberTwo = toConvert[1].getContent();
40.     String numberThree = toConvert[2].getContent();
41.     
42.     println(numberOne);
43.     println(numberTwo);
44.     println(numberThree);
45.     
46.     float[] returnValues = new float[3];
47.     returnValues[0] = float(numberOne);
48.     returnValues[1] = float(numberTwo);
49.     returnValues[2] = float(numberThree);
50.     
51.     return returnValues;
52.     
53.   }
54.   
55.   // Find the biggest number
56.   float highestValue( float numberRange[] )
57.   {
58.     
59.     float number = 0;
60.     
61.     if ( numberRange[0] > numberRange[1] && numberRange[0] > numberRange[2] )
62.     {
63.       number = numberRange[0];
64.     }
65.     else if ( numberRange[1] > numberRange[0] && numberRange[1] > numberRange[2])
66.     {
67.       number = numberRange[1];
68.     }
69.     else if ( numberRange[2] > numberRange[0] && numberRange[2] > numberRange[1])
70.     {
71.       number = numberRange[2];
72.     }
73.     
74.     return number;
75.     
76.   }
77.   
78. }

Has anyone got any ideas or suggestions as to what i can do to resolve this issue?

Your time is much appreciated,

Daniel Groves.  

I'm pretty new to Processing, but am working on uni coursework for a Processing unit.  For the coursework we have to visualise the data from the weather feed that runs one of the campus buildings.  While doing this I have encountered the error "Cannot convert from XMLElement[] to XMLElement" in my BarGroup class, posted below.  

Any help or feedback would be hugely appreciated as I am at complete loss.  

1. import processing.xml.*;
2. 
   
3. class BarGroup
4. {
5.   
6.   String     xmlUrl;
7.   XMLElement xml       = new XMLElement(getParent(), xmlUrl);
8.   XMLElement xmlValue  = xml.getChildren("channel/item/description");
9.   float[]    data      = convertToFloat(xmlValue);
10.   int        groupXpos
11.   Bar[]      group     = new Bar[3];
12.   
13.   // COnstructor
14.   BarGroup ( String url, int xPos)
15.   {
16.     
17.     xmlUrl = url;
18.     groupXpos = xPos;
19.     
20.     group[0] = new Bar( color(0, 255 ,0 ), 0, map( data[0], 0, highestValue(), 0, 600), (10 * 1) );
21.     group[1] = new Bar( color(0, 255 ,0 ), 0, map( data[1], 0, highestValue(), 0, 600), (10 * 2) );
22.     group[2] = new Bar( color(0, 255 ,0 ), 0, map( data[2], 0, highestValue(), 0, 600), (10 * 3) );
23.     
24.   }
25.   
26.   // Show the group of Bars
27.   void display()
28.   {
29.     for (int i = 0; i < 2; i++)
30.     {
31.       group[i].display();
32.     }
33.   }
34.     
35.   // Turn the XMLElement into an Array of Floats
36.   float[] convertToFloat( XMLElement[] toConvert )
37.   {
38.     
39.     String numberOne = toConvert[0].getContent();
40.     String numberTwo = toConvert[1].getContent();
41.     String numberThree = toConvert[2].getContent();
42.     
43.     println(numberOne);
44.     println(numberTwo);
45.     println(numberThree);
46.     
47.     float[] returnValues = new float[3];
48.     returnValues[0] = float(numberOne);
49.     returnValues[1] = float(numberTwo);
50.     returnValues[2] = float(numberThree);
51.     
52.     return returnValues;
53.     
54.   }
55.   
56.   // Find the biggest number
57.   float highestValue( float numberRange[] )
58.   {
59.     
60.     if ( numberRange[0] > numberRange[1] && numberRange[0] > numberRange[2] )
61.     {
62.       return numberRange[0];
63.     }
64.     else if ( numberRange[1] > numberRange[0] && numberRange[1] > numberRange[2])
65.     {
66.       return numberRange[1];
67.     }
68.     else if ( numberRange[2] > numberRange[0] && numberRange[2] > numberRange[1])
69.     {
70.       return numberRange[2];
71.     }
72.     
73.   }
74.   
75. }

Thanks in advance for any help, feel free to ask questions.  
Daniel Groves