Need help with a simple Java thing involving array of objects

[Jeremy8]

So I have 3 classes. I need to have 10 circles with random dimensions and placement. I'm stuck at an early stage of writing this... I have a feeling it's because of toString? I don't understand how to use it. But whenever I run this the array is filled with all nulls.

*code removed by me*

Please help me! I've been stuck on this one basic thing for a while. After I figure it out I think it'll be easy to finish the rest of this. What am I doing wrong?

[Fubarable]

What if you change this:

allInformation += collection1[circle] + "\n";

to this:

allInformation += collection1[circle].toString() + "\n";

The reason being is that you are adding Circle objects to your allInformation String, and I don't think you want to do that. I think that you want each Circle's toString() output to be added to the allInfo string, and so you'll have to specifically request this in your code.

[Jeremy8]

Yah I tried that and it compiles but then I get this error message when I run it:

java.lang.NullPointerException
at Collection.printAll(Collection.java:29)
at Circles.main(Circles.java:14)

I don't know what that means

But you're right about what I'm trying to do.

[Fubarable]

The NPE means that you're trying to use objects that have not yet been initialized. Please note that when you create and initialize an array of objects, you just initialize the array, not the objects it contains. You have to do that separately by looping through the array and initializing each object. Consider doing this in your Collection constructor.

[paul pasciak]

This is excellent code.
It is about 90% working.
It needs a few details.

The first detail is that it needs
a method that fills the collection
with 'new Circles' (hint).

I made such a method and called it,
"public void fillWithRandomCircles()",
and placed it in the Collection class.

REGARDING "toString()":

It is being used entirely correctly
in this code.
"toString()" is a method ALL CLASSES
have in Java -- even if you make up
your own class, "toString()" will be
there along with eight other methods
you can use, but don't know about yet.

To find these methods, along with
toString(), click on
"java.lang.Object"
anywhere in the Java API.

YOUR CODE overides toString(). To
see how toString normally behaves,
comment out your toString() code,
re-compile, then run it and see.

[Jeremy8]

Thanks guys! I think it's working now! I'll let you know if I run into any other issues.