Example solution for stackoverflow question: http://stackoverflow.com/q/39986249/3442851

ConeStuff.java

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

/*
output:

    ** cones before **
    label: bar
    height: 13.37
    radius: 4.2

    found foo: false
    found bar: true
    found baz: false

    ** cones after **
    label: bar
    height: <random double>
    radius: <random double>

*/
class ConeStuff {

    List<Cone> cones = new ArrayList<>();

    ConeStuff() {
        doWork();
    }

    public static void main(String[] args) {
        new ConeStuff();
    }

    void doWork() {
        // add some cones to the list and do other fancy stuff
        cones.add(new Cone("bar", 13.37, 4.2));
        // ...
        printCones("cones before");

        // random for random values
        Random random = new Random();
        double height;
        double radius;
        // use method from task to search for labels
        boolean found;
        for (String label : new String[] {"foo", "bar", "baz"}) {
            height = random.nextDouble() * 100;
            radius = random.nextDouble() * 100;
            found = findAndAdjustCone(label, height, radius);
            System.out.println("found " + label + ": " + found);
        }

        // see if cones are changed
        printCones("cones after");
    }

    // method to find and change cones
    boolean findAndAdjustCone(String label, double height, double radius) {
        // default is false
        boolean found = false;
        // iterate over all cones
        for (Cone cone : cones) {
            // if cone label equals the given label in the arguments...
            if (cone.label.equals(label)) {
                // set found to true
                found = true;
                // change values of cone
                cone.height = height;
                cone.radius = radius;
                // break for-loop because cone was found
                break;
            }
        }
        // return if cone was found or not
        return found;
    }

    void printCones(String title) {
        System.out.println("\n** " + title + " **");
        for (Cone cone : cones) {
            System.out.println("label: " + cone.label + "\n" +
                "height: " + cone.height + "\n" +
                "radius: " + cone.radius + "\n");
        }
    }

    // cone bean
    class Cone {
        String label;
        double height;
        double radius;

        Cone(String label, double height, double radius) {
            this.label = label;
            this.height = height;
            this.radius = radius;
        }
    }
}