静态方法如何改变变量？ (爪哇)

Question

I have this class:

class Inventory {
    boolean smallknife = false;
    boolean SRLockerkey = false;
    void checkinv () {
        System.out.println("You have the following items in your inventory: ");
        System.out.println(smallknife);
        System.out.println(SRLockerkey);
    }
}

The Inventory test class

class InvTester {
    public static void main(String args[]) {
        Inventory TestInv = new Inventory();
        System.out.println("This program tests the Inventory");
        SKTrue.truth(TestInv.smallknife);
        TestInv.checkinv();
    }
}

and this class with a method to try to change the inventory

class SKTrue {
    static boolean truth(boolean smallknife) {
        return true;
    }
}


class SKTrue {
   static void truth(boolean smallknife) {
    smallknife = true;
  }
}

I would like to avoid using TestInv.smallknife = SKTrue.truth(TestInv.smallknife) and still change the variable but with a method. Is there a way that this can be done? I want that the truth method does the variable changing and I don't want to do the pass by reference part in the Inventory Test class. Thanks. Is there a way to do this in Java? (I also tried the second version which I think makes more sense)

Answer 1

Assuming you don't want to reference the variables directly (ie TestInv.smallknife = blah ), the best practice in Java is to declare the variables as private and access them by getters/setters, eg:

class Inventory {

    private boolean smallknife;

    public boolean isSmallknife() {
        return smallknife;
    }

    public void setSmallknife(boolean smallknife) {
        this.smallknife = smallknife;
    }

}

Now, you can do this:

Inventory TestInv = new Inventory();
TestInv.setSmallknife(SKTrue.truth(blah));

It is called Encapsulation, you can read more about it here .