创建参数化构造函数

Question

So, I'm doing my homework assignment right now. However, I stuck in the several parts of this assignment.

public class CheeseCake {
    //Instance Variables        
    private double Cheese;
    private int StrawBerry;
    private double Cream; 

    public CheeseCake() {
           Cheese = 0;
           StrawBerry = 0;
           Cream = 0;
        }

//Constructor       
    public CheeseCake (double milk, int fresh, double temp)
    {

    Cheese = milk;
   StrawBerry = fresh;
    Cream = temp;

    }



// (setter)

    public void setCheese(double milk){
        Cheese = milk;
    }
    public void setStrawBerry(int fresh){
        StrawBerry = fresh;
    }       
    public void setCream(double temp){
         Cream = temp;
}

//(getter)

public double getCheese(){
    return Cheese;
}

    public int getStrawBerry(){
        return StrawBerry;
}

    public double getCream(){
        return Cream;
}

{

}
//Method to display data, (need to work on this)
public void display() {

System.out.println(Cheese);
System.out.println(StrawBerry);
System.out.println(Cream);
System.out.println("You used " + Cheese + " g of Creamcheese to make Cheese");
System.out.println("You used " + StrawBerry + " StrawBerry to make StrawBerry CheeseCake");
System.out.println("You used " + Cream + " g of Cream to make Cream Cheese");


}
}

And this is my demo which help me to run this program.

 public class Demo {

    public static void main(String[] args) {

        CheeseCake cheesecake = new CheeseCake();


        cheesecake.setCheese(5);


        cheesecake.setStrawBerry(20);


        cheesecake.setCream(10);

        cheesecake.display();
    }
}

So, my problem is I finish to create 3 instance methods and getter, setter methods. Also, I create my default constructor. But I'm not sure how to create parameterized constructors which this. "Create a parameterized constructor that takes all instance variables as parameters, and sets the instance variables to the values provided by the parameters"

Also, I'm not sure what my teacher wants me to do in the demo methods.

Create a class called Demo.java. This class will contain your main method Create an instance of your class by using the default constructor. Call all your objects set methods to assign values to your object Call the objects display method, to print out it's values Create another instance of your class by using the parameterized constructor Call the objects display method, to print out it's values

Is my demo methods is right? or I should add more stuff. Also, should I add more constructors to make parameterized constructors? I have no idea how to make parameterized constructors.

Answer 1

Default constructor doesn't take any argument. Your second constructor is a parameterized constructors. And your code is okay you just need to create one more parametrized copy constructor which takes another instance as argument. ie

 public CheeseCake (CheeseCake ck)
    {

    Cheese = ck.getCheese();
    StrawBerry = ck.getStrawBerry();
    Cream = ck.getCream();

    }

And now you need to create an instance in demo class using this constructor

CheeseCake cheesecake2 = new CheeseCake(cheesecake);//Pass first object as argument

Now call display method for 2nd object.

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