Help with Bottle Class directions

[g33k3r]

Hey guys, I appreciate the help in advance. I have an assignment that I am currently working on but don't seem to understand how I would get this to work. The following is the assignment:

Project 1: Write a Bootle class. The class has these 13 methods: read(),set(int),set(Bottle), add(Bottle), subtract(Bottle), multiply(Bottle), add(int), subtract(int), multiply(int), equals(Bottle), and toString() methods. All add, subtract,multiply and divide methods return a Bottle. Your Bottle class must guarantee bottles always have a positive value. Use System.exit(0) to end the program if a negative bottle value is generated.

What I do not understand is this section: All add, subtract,multiply and divide methods return a Bottle.

How can I add values if I am returning a value?

I have to make it work with the provided BottleDemo.java which I made a few changes:

import java.util.Scanner;

// test driver for the Bottle class
public class BottleDemo {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int x;
		Bottle bottle1 = new Bottle();
		Bottle bottle2 = new Bottle();
		Bottle bottle3 = new Bottle();
		Bottle bottle4 = new Bottle();
		Bottle bottleAve = new Bottle();
		System.out.println("please enter a number for bottle1:");
		bottle1.read();
		System.out.println("bottle1 is this value " + bottle1.value);
		System.out.println("please enter a number for bottle2:");
		bottle2.read();
		System.out.println("please enter a number for bottle3:");
		bottle3.read();
		System.out.println("please enter a number for bottle4:");
		bottle4.read();
		bottleAve = bottleAve.add(bottle1);
		bottleAve = bottleAve.add(bottle2);
		bottleAve = bottleAve.add(bottle3);
		bottleAve = bottleAve.add(bottle4);
		bottleAve = bottleAve.divide(4);
		System.out.println("The 4 bottle average is: " + bottleAve);
		if (bottle1.equals(bottle3)) {
			System.out.println("Bottle1 and bottle3 are equal");
		} else {
			System.out.println("Bottle1 and bottle3 are not equal");
		}
		System.out.println("Enter an integer to add to bottle 1");
		x = scan.nextInt();
		bottle2 = bottle1.add(x);
		System.out.println("Adding your number " + x + " to  bottle1 gives "
				+ bottle2);
		bottle2 = bottle1.add(bottle3);
		System.out.print("Adding the number " + bottle3 + " to ");
		System.out.println("Bottle1  gives " + bottle2);
	}
}

The following is the code that I have written so far:

import java.util.Scanner;

public class Bottle {

	/**
	 * 
	 * 
	 * @param args
	 */

	private Scanner scan = new Scanner(System.in);
	private int value;

	public Bottle() {

		value = 0;

	}
	
	// methods
	/*
	 * 
	 * multiply(int) equals(Bottle) toString()
	 */

	public void read() {
		value = scan.nextInt();
	}

	public void set(Bottle bottle1) {
		value = bottle1.value;

	}

	public void set(int bottle1) {
		value = bottle1;
	}

	public Bottle add(Bottle bottle1) {
		value = value + bottle1.value;
		return this;

	}

	public Bottle subtract(Bottle bottle1) {

		return bottle1;

	}

	public Bottle multiply(Bottle bottle1) {

		return this;

	}

	public Bottle divide(Bottle bottle1) {
		
		return this;

	}

	public Bottle add(int bottle1) {

		return this;

	}

	public Bottle subtract(int bottle1) {

		return this;

	}

	public Bottle multiply(int bottle1) {

		return this;

	}

	public Bottle divide(int bottle1) {
		value = value / bottle1;
		return this;

	}

	public String toString() {
		return name;
	}

	public boolean equals(Bottle bottle1) {
		if (this == bottle1) {
			return true;
		}

		else {
			return false;
		}

	}

}

Thanks again for the help.

[Danieldcc]

public Bottle add(Bottle bottle1) {         
value = value + bottle1.value;
return this;       }

this.value += bottle1.value;
return this;

wouldn't that work?

I'm a newbie too but I'm giving it a try. you're not passing in a value, you're passing in an object and the using that objects 'value' to add to the current object you working on 'this'

I might get slammed by moderator but this is my attempt...sorry moderator

[Fubarable]

public Bottle add(Bottle bottle1) {         
value = value + bottle1.value;
return this;       }

this.value += bottle1.value;
return this;

wouldn't that work?

I'm a newbie too but I'm giving it a try. you're not passing in a value, you're passing in an object and the using that objects 'value' to add to the current object you working on 'this'

I might get slammed by moderator but this is my attempt...sorry moderator

I'm not going to slam you, but I am going to ask what advantage your code would have over the original poster's code.