I've been trying to store an array in an array list by using a method similar to this:
static ArrayList<double []> Shapes;
public static void Test(){
double [] Test = new double [2];
Test[0] = 1;
Test[1] = 2;
Shapes.add(Test);
}
I'm not really sure if this is something you can do but if anybody knows how to work this out, it would be much appreciated.
Basically, this won't work because you need to call = new ArrayList<double[]>(); at some point (or without the double[] in some java versions).
If you want to store info about different shapes, you should really think about just making a class for them and then storing instances of that class though.
Your code looks nearly correct in Java syntax, although needs style changes as Java convention is to use lowercase first letters for variables and methods. And other posters have pointed out the missing 'new ArrayList' to create the array.
The problem is that from an object-oriented design point of view, using double[] to hold info about different shapes is not good design. I think what you want is and ArrayList of ShapeInfo rather than an ArrayList of double[]. ShapeInfo can be an interface which can be implemented by various classes. Something like this will allow you to have different info parameters for each shape as well as having a common method (getSummary) for all shapes that can be used in loops.
import java.util.ArrayList;
import java.util.List;
public class Shapes {
private static List<ShapeInfo> shapes;
public static void main(String[] args) {
shapes = new ArrayList<>();
ShapeInfo info = new CircleInfo(1, 2, 3);
shapes.add(info);
// Check what's there
for (ShapeInfo shape : shapes) {
System.out.println(shape.getSummary());
}
}
}
interface ShapeInfo {
String getSummary();
}
class CircleInfo implements ShapeInfo {
private double centreX, centreY, radius;
public CircleInfo(double centreX, double centreY, double radius) {
this.centreX = centreX;
this.centreY = centreY;
this.radius = radius;
}
@Override
public String getSummary() {
return "Centre is at (" + centreX + "," + centreY + ") and radius is " + radius;
}
}
