Help ArrayList.add()

[eNine]

Can someone please tellme what is wrong with my code? I'm new Java but I haven't had any trouble with ArrayList until I tried to write the code below. For some reason, the Rectangle2D 's are not being added to my arrayList.


import java.util.ArrayList;
import java.awt.geom.Rectangle2D;


public class Hat {
ArrayList<Rectangle2D.Double> rectangles = new ArrayList<Rectangle2D.Double>(5);

public Hat(){
}

Hat(double x, double y, double w, double h){
rectangles.add((new Rectangle2D.Double(x,y,w,h) ) );
}

public void countHats(){
System.out.println("There are "+ rectangles.size() +" in list");

}

public static void main(String[] args){
Hat h = new Hat();
int limit =5;
int randomLim = 100;
for(int i=0;i<limit;i++)
{
new Hat(Math.random()*randomLim,Math.random()*randomLi m,Math.random()*randomLim,Math.random()*randomLim) ;
}
h.countHats();
}

}

[hardwired]

You made a new Hat each time with only one rectangle in the ArrayList of the Hat for each trip through the for loop. So you ended up with 5 Hats. Instead, make an add method so you can add rectangles to any Hat. Then you can have a Hat with multiple rectangles. In your h.countHats() statement you get zero because you never did anything with the Hat h you created before the for loop. Try this:

Code:

import java.util.ArrayList;
import java.awt.geom.Rectangle2D;

public class HatRx {
    ArrayList<Rectangle2D.Double> rectangles = new ArrayList<Rectangle2D.Double>(5);

    public HatRx(){} 

    void add(double x, double y, double w, double h){
        rectangles.add((new Rectangle2D.Double(x,y,w,h) ) ); 
    }

    public void countHats(){
        System.out.println("There are "+ rectangles.size() +" in list");
    }

    public static void main(String[] args){
        HatRx h = new HatRx();
        int limit =5;
        int randomLim = 100;
        for(int i = 0; i < limit; i++) {
            h.add( Math.random()*randomLim, Math.random()*randomLim,
                   Math.random()*randomLim, Math.random()*randomLim);
        }
        h.countHats();
    }
}

[eNine]

thanks. that was exactly my problem.