Well, either bb or nn is null.  You could do some quick check's before hand...

1. if (bb != null && nn != null) {
2.     if(bb.bx<nn.nx+25-x&& bb.bx>nn.nx-25-x&& bb.by>=nn.y+35){
3.       onblock=true;
4.     }else{
5.        onblock=false;
6.     }
7. } else {
8.    System.err.println("oh no, I'm null - pressing on and will try again next time.");
9. }

Or a quick try block might be better.  That would catch everything...

1. try {
2.     if(bb.bx<nn.nx+25-x&& bb.bx>nn.nx-25-x&& bb.by>=nn.y+35){
3.       onblock=true;
4.     }else{
5.        onblock=false;
6.     }
7. } catch (Exception e) {
8.      System.err.println("oh no, I'm null - pressing on and will try again next time.");
9. }

Although what I'm trying to do isn't technically working, probably becuz I entered it in wrong, the advice helped very much.  Yes, it was the bb that was the null; when I had the original class in there, it didn't have a constructor, so I didn't have a constructor for the block class either, so I had to change that.

Thanks for the help,

Blake

Phi.lho I believe exceptions are only slow if it triggers an exception.  There is little cost in the try statement itself.  But in any case, I was suggesting it as a way to help troubleshoot, so he could see a bit of what is going on.

Unrelated question, sort of, but if I compose a class in another (bb in jump, for example), I know that I would have to make the constructor for it (other i get that nullpointerexception error).  What do I do if I want the constructors to be of the created objects of the class (b1, for ex.).  Like, I have made it so I just have bx,by for the constructor, but that just makes that at 0, and if I put b1.bx or bb.bx, I just get null error again.

Can you illustrate your case with a simple, made-up sketch? I fear I don't fully understand the question.

Umm....yea, here's some of the code.

1. class jump{
2.   float jx;
3.   boolean above=false;
4.   boolean under=false;
5.   nicolai nn;
6.   block bb;
7.   boolean onjump;
8.   boolean fall=false;
9.   int jumpy=ground-114;
10.   boolean onblock=false;
11.   float bx,by;
12.  
13.   jump(int ix, nicolai inn, block ibb){
14.     jx=ix;
15.     nn=inn;
16.     bb=ibb;
17.     bb=new block(bx,by,nn);
18.   }

So that is the constructor used for the jump class.  Then, I have this for the actual block:

1. if(nn.y>=bb.by){
2.       onblock=true;
3.     }else{onblock=false;}

It was different and more exact, but it wasn't working when I tested it, so I had it say that whenever onblock is true, it made an ellipse.  It did make an ellipse, but it wouldn't make it false until the guy was above the screen, which means bb.by has to be zero, so I need to find a way to make that change. Is there an easy one?

Sorry, I am still lost, I must be tired...
But I see something strange in your constructor:

1.     bb=ibb;
2.     bb=new block(bx,by,nn);

You assign bb, then you overwrite it with a new block not using ibb. So you make a useless assignment and drop the values of a parameter.
You want to do a copy of ibb, to reference it (blocks are specific to the game, right?) or something else?

Or perhaps your whole class system should be revised...
I find odd that a jump references a character instead of the reverse... And why have a class for a jump, anyway? There are blocks, and the character should be able to detect them and jump on them or over them.

The constructor thing is what I now assume is the problem, thank you.  But I can't seem to figure out how to put in a constructor including ibb without getting the null point exception error again.  The last thing I tried was this, but it didn't work:

1. bb=ibb;
2. bb=new block(ibb.bx,ibb.by,nn);

Yea, the jump class includes the actual jumping of the character, but the class is mainly for mid-air blocks that the character has to land on.  The blocks are coin blocks, like in Mario.