Processing 1.0 - Processing Discourse - NullPointerException Error

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NullPointerException Error (Read 4982 times)

Sparragus

NullPointerException Error
Dec 23^rd, 2007, 4:06am

Hey everyone. I'm getting this error after running my code

Quote:

void setup()
{

String[] lines = loadStrings("database_clean.txt");

Record[] drivers = new Record[lines.length];
int driverCount = 0;

for (int i = 0; i < lines.length; i++)
{
if (lines[i].startsWith("Card:"))
{
drivers[driverCount].cardName = lines[i];
driverCount++;
}
}

for (int i = 0; i < driverCount; i++)
println(i + "-->" + drivers[driverCount].cardName);
}

class Record {
String cardName;
}

Here's the link to the database_clean.txt
http://sparragus.freehostia.com/database_clean.txt

Error is ...
Quote:

java.lang.NullPointerException

at Temporary_774_8919.setup(Temporary_774_8919.java:13)

at processing.core.PApplet.handleDisplay(PApplet.java:1390)

at processing.core.PGraphics.requestDisplay(PGraphics.java:690)

at processing.core.PApplet.run(PApplet.java:1562)

at java.lang.Thread.run(Thread.java:613)

I'm running Processing 135 in Mac OS 10.5
Thanks in advance.

fjen

Re: NullPointerException Error
Reply #1 - Dec 23^rd, 2007, 8:51am

this:

new Record[lines.length];

just creates the array but it is still empty (filled with "null"s).
that's why this:

drivers[driverCount]

raises the error.
you have to create every object before you can use it:

if (lines[i].startsWith("Card:"))
{
drivers[driverCount] = new Record();
drivers[driverCount].cardName = lines[i];
...

F

Sparragus

Re: NullPointerException Error
Reply #2 - Dec 24^th, 2007, 6:12am

Now I'm getting this...

/tmp/build2333.tmp/Temporary_5429_4545.java:13:39:13:39: Syntax Error: ArrayInitializer expected after this token

because of this...
Quote:

void setup()
{

String[] lines = loadStrings("database_clean.txt");

Record[] drivers;
int driverCount = 0;

for (int i = 0; i < lines.length; i++)
{
if (lines[i].startsWith("Card:"))
{
drivers[driverCount] = new Record[];

drivers[driverCount].cardName = lines[i];
driverCount++;
}
}

for (int i = 0; i < driverCount; i++)
println(i + "-->" + drivers[driverCount].cardName);
}

class Record {
String cardName;
}

steven

Re: NullPointerException Error
Reply #3 - Dec 24^th, 2007, 8:32am

try this

Code:


void setup()
{

  String[] lines = loadStrings("database_clean.txt");

  Record[] drivers = new Record[lines.length];
  int driverCount = 0;

  for (int i = 0; i < lines.length; i++) {  
    if (lines[i].startsWith("Card:")){  
	drivers[driverCount] = new Record();

	drivers[driverCount].cardName = lines[i];  
	driverCount++;  
    }  
  }  

  for (int i = 0; i < driverCount; i++)
    println(i + "-->" + drivers[i].cardName);
}

class Record {  
  String cardName;  
}

There was 3 things that didn't work.
1) You needed to specify an array size (like you did in your first post)

2) you need to write
Quote:

drivers[driverCount] = new Record();

and not
Quote:

drivers[driverCount] = new Record[];

() is not the same as []

3) Change "driverCount" by "i" in this line to avoid an ArrayOutOfBound Error
Quote:

println(i + "-->" + drivers[driverCount].cardName);

http://www.computerarts.ca

Sparragus YaBB Newbies Offline Posts: 6	Re: NullPointerException Error Reply #4 - Dec 24^th, 2007, 11:33am Damn. Thank you Steven and fjen. I love this forum. Thank to you guys one learns a lot. Dont be surprised if I bring up some more of my buggy code. Hehe, I always try to do my best, but there are times I have no idea what the hell is messing the code. Thank you once again.

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