Thread: Arraylist help

I'm kind of new at programming, and I'm trying to create an arraylist to hold 6 or 7 colors that can be used in a for loop so that they can be assigned like color(0), color(1), so that in my loop, I can make it say setColor(color(loop)). Loop is my int from my for loop. Basically, each time it runs the loop, I want the color to be the next one in the arraylist.

for (int loop = 0; loop <= 5; loop++){
    		myPen.setColor(color(loop));
    	}

Is this possible?

ArrayList colors = new ArrayList();
//add all colors to the list
for ( int i = 0; i < colors.size(); i++ ){
    myPen.setColor(colors.get(i));
}

Well, I've been trying since you've posted that, and haven't been able to make it work. I'm not sure if I added the colors to the arraylist correctly, and "myPen.setColor(colors.get(i));" doesn't seem to want to work.

Please post the code and errors you are receiving, both of which are a wealth of information to help solve your problem

Basically it makes a circle centered in a hexagon, but once I figure out how to do this arraylist, I woulld like to make the sides keep changing colors in a pattern for a little bit. I can figure that part out, I just need to figure this out.

import gpdraw.*;
import java.awt.Color;
	import java.util.ArrayList;
 
public class Benzene {
	private DrawingTool myPen;
    private SketchPad myPap;
 
    public Benzene(){
    	myPap = new SketchPad(800,800);
    	myPen = new DrawingTool(myPap);
    }
 
    public void draw(){
    	Color cBlue = new Color(0,0,255);
    	Color cRed = new Color(255,0,0);
    	Color cGreen = new Color(0,255,0);
    	Color cPurple = new Color(255,0,255);
    	Color cCyan = new Color(0,255,255);
    	Color cYellow = new Color(255,255,0);
    	Color cOrange = new Color(255,132,0);
    	myPen.setColor(cOrange);
    	myPen.setWidth(4);
    	myPen.drawCircle(100);
    	myPen.up();
    	myPen.move(-70,120);
    	myPen.down();
    	myPen.move(70,120);
 
		ArrayList colors = new ArrayList();
		colors.add(cBlue);
		colors.add(cRed);
		colors.add(cGreen);
		colors.add(cPurple);
		colors.add(cCyan);
		colors.add(cYellow);
		colors.add(cOrange);
 
    	for (int i = 0; i <= colors.size(); i++){
    		myPen.setColor(colors.get(i));
			myPen.turnRight(60);
    		myPen.forward(140);
    	}
 
 
    }
}

setColor(java.awt.Color) in gpdraw.DrawingTool cannot be applied to (java.lang.Object)




I have a feeling that I added the colors incorrectly.

ArrayList is generic, so if you do not define the objects put in, you must do so when you take them out. Solution 1 is to cast the object when you get it from the list

myPen.setColor((Color)colors.get(i));

Solution 2 - which provides compile time checks - is to use generics

ArrayList<Color> colors = new ArrayList<Color>();

Hi TreeChopper,

you need to replace

for (int i = 0; i <= colors.size(); i++){
myPen.setColor(colors.get(i));

with

for (int i = 0; i <= colors.size(); i++){
myPen.setColor((Color)(colors.get(i)));

because get() method will return Object class object which we need to cast explicitly to get our required object.

Thank you very much, it works exactly how I wanted it to.