Question
Create a generic class with a type parameter that simulates drawing an item at random out of a box. This class could be used for simulating a random drawing. For example, the box might contain Strings representing names written on a slip of paper, or the box might contain Integers representing a random drawing for a lottery based on numeric lottery picks. Create an add method that allows the user of the class to add an object of the specified type along with an isEmpty method that determines whether or not the box is empty. Finally, your class should have a drawItem method that randomly selects an object from the box and returns it. If the user attempts to drawn an item out of an empty box, return null . Write a main method that tests your class.
Answer
PROGRAM CODE:
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class RandomBox<T> {
private List<T> items;
private Random random;
public RandomBox() {
items = new ArrayList<>();
random = new Random();
}
public void add(T item) {
items.add(item);
}
public boolean isEmpty() {
return items.isEmpty();
}
public T drawItem() {
if (isEmpty()) {
return null;
}
int index = random.nextInt(items.size());
return items.remove(index);
}
public static void main(String[] args) {
RandomBox<String> nameBox = new RandomBox<>();
nameBox.add("John");
nameBox.add("Emma");
nameBox.add("Michael");
nameBox.add("Sophia");
System.out.println("Drawing names from the box:");
while (!nameBox.isEmpty()) {
String name = nameBox.drawItem();
System.out.println("Drawn name: " + name);
}
RandomBox<Integer> numberBox = new RandomBox<>();
numberBox.add(10);
numberBox.add(20);
numberBox.add(30);
numberBox.add(40);
System.out.println("\nDrawing numbers from the box:");
while (!numberBox.isEmpty()) {
Integer number = numberBox.drawItem();
System.out.println("Drawn number: " + number);
}
}
}
OUTPUT OF THE PROGRAM CODE:
Drawn name: Sophia
Drawn name: Emma
Drawing numbers from the box:
Drawn number: 40
Drawn number: 30
Drawn number: 20
Drawn number: 10