存储布尔值

Question

I have the problem how to change boolean value of a given class so that once it is encountered again it has the value last set. This is my class

public class Sandwich {
    private String type;
    private double price;
    private String ing;
    public boolean owned;

    Sandwich (String t, double p, boolean o){
        type = t;
        price = p;
        owned = o;
    }

    public boolean getO(){
        return this.owned;
    }

    public void setO(boolean o){
        this.owned = o;
    }

    public String getType(){
        return this.type;
    }
}

and place where it is accessed and supposed to change:

public void purchase(Sandwich s) {
    boolean owned = s.owned;

    //I tried also with accessor and mutator here but then changed to public
    String type = s.getType();
    if (owned == false) {
        if (money <= 0){ 
            System.out.println("Worker " + this.name + " can not buy " + type + " sandwich, cuz he doesn't have enough money");
        } else {
            System.out.println("Worker " + this.name + " can buy " + type + " sandwich");
            this.money = money;
            owned = true;

            //this is the place where it is supposed to change value to true (sandwich was bought and has owner now
            s.owned = owned;
        }
    } else if (owned == true) {
        System.out.println("Worker " + this.name + " can not buy " + type + " sandwich cuz it was bought");
        System.out.println("Test");
    }
}

Problem is that although a given sandwich was bought in the past its owned value is set to false each time I try to run this code. I need for the sandwich to record changed value of owned so that next time I run the condition will be owned == true. How can it

Answer 1

There seems to be a flaw in your design. You need to create a relationship between the Worker and the sandwish type.

What you can do is simply implement a List of purchased sandwish types in the worker class and compare against it whenever a worker purchases a sandwish.

Or if you want, you can have a hashmap of all sandwish types with a boolean value that indicates whether the type has already been purchased or not.

Answer 2

You created get and set routines and then didn't use them. I would change the code to this.

    public void purchase(Sandwich s){
            String type = s.getType();
            if (!(s.getO())){
                if (money <= 0){ 
                    System.out.println("Worker " + this.name + " can not buy " + type + " sandwich, cuz he doesn't have eno

ugh money");
                } else {
                    System.out.println("Worker " + this.name + " can buy " + type + " sandwich");
                    this.money = money;
                    s.setO(true);
                }
            } else {
                System.out.println("Worker " + this.name + " can not buy " + type + " sandwich cuz it was bought");
                System.out.println("Test");
            }
     }

Answer 3

Just remove

boolean owned = s.owned;

and use s.getO() where you have used owned

eg

if (owned == false){ 

can be

if (!s.getO()){

And use the setter method s.setO(true/false) to change it.

eg

owned = true;
s.owned = owned;

can be replaced by

s.setO(true);