Question

I will start by explaining the scenario.
I have to create a Vector to hold a list of Circles.
Then I create a circle object, and add it to the Vector.
Finally I have to print the state of each circle in the list (the state isn’t important to define, just it’s colour and position etc).

Basically my problem is, how do I hold the circles so that I can then pass in the name of one of them and it will print the correct circle’s state. It may be clearer to show you my code.

I have 3 classes, that main one called Lab83Test, the Vector one, called CircleList, and the Circle one, called Circle. (The formatting has gone weird and I can’t fix it, so apologies!)

Lab83Test:

public class Lab83Test {

    public static void main(String[] args) {
        makeNewCircle();
    }
    public static void makeNewCircle() {
        CircleList newList = new CircleList();
        Circle newCircle = new Circle();
        newList.addCircle(newCircle);
        newCircle.makeVisible();
        newList.printDetails();
    }
}

CircleList:

import java.util.Vector;

public class CircleList {
    private Vector circleVector;

    public CircleList() {
        circleVector = new Vector();
    }
    public void addCircle(Circle circleName) {
            circleVector.add(circleName);
            printDetails();
    }
    public void addCircleToPlace(Circle circleName, int pos) {
        circleVector.add(pos, circleName);
        printDetails();
    }
    public void removeCircleFromPos(int pos) {
        circleVector.remove(pos);
        printDetails();
    }
    public void removeAllCircles(int pos) {
        circleVector.clear();
        printDetails();
    }
    public void printDetails() {

    }
}

The circle class isn’t too important, and it has a lot of methods for moving the circle and stuff. The main thing is that it has to return its state.

Answer 1

If you just want to iterate over all Circel in your list and print their name, you can do it this way:

public void printDetails() {
  for (Circle c: circleVector) {
    System.out.println(String.format("%s: center=(%.1f/%.1f) radius=%.1f", c.getName(), c.getCenterX(), c.getCenterY(), c.getRadius()));
  }
}

I don’t know how your Circle class looks so I just assumed some method names.

If you want to find a specific circle by name:

for (Circle c: circleVector) {
  if (c.getName().equals(nameToFind)) return c;
}

Or you could use a Map<String, Circle> instead of your vector and just do return circleMap.get(name);. Your addCircle() would then look like this:

public void addCircle(Circle circle) {
  circleMap.add(circle.getName(), circle);
  printDetails();
}

Edit1: regarding your comment: Your vector does not have a defined type. Change this:

...
public class CircleList {
  private Vector<Circle> circleVector;

  public CircleList() {
    circleVector = new Vector<Circle>();
  }
  ...