Java – OOP using original value of a variable in another class

I Want to use attributes such as the volume and capacity of a cup, I have made base values for the capacity and volume size of a cup in a liquadContainer class. i want to set my cup to the volume and capacity I have set in my liquadcontainer class and display the volume and capacity. however, I am not sure how to use the volume and capacity value in the other class and use it and display it, This is what i have done so far:

public class Cup extends LiquadContainer
{
    // ---------------------------------------------------------------------
    // class variables
    // ---------------------------------------------------------------------
    
    private ContainerColour myColour;
    private int iCapacity;
    private int iVolume;
    private int iTemp;
    private int iFill;
    private String SzMaterial;

    private Boolean bEmpty;
    
    // ---------------------------------------------------------------------
    // Constructors
    // ---------------------------------------------------------------------
    
    public Cup()
    {
        super();
        reset();
        return;

    }
    
    public Cup (Cup original) {
        this.iCapacity = original.getCapacity();
        this.iVolume = original.getVolume();
        this.SzMaterial = original.getMaterial();
    }

    public Cup(int size) 
    {
        this();
        super.setCapacity(size);
        setColour(ContainerColour.NOT_SET);
        return;
    }
    
    public Cup (int size , ContainerColour colour)
    {
        this (size);
        setColour(colour);
        return;
    }
    
    //setters
    
    //main
    public void display() 
    {

        System.out.println("Cup: \nCapacity = " + this.iCapacity);

        System.out.println("Volume = " + this.iVolume);
        System.out.println("Colour = " + getColour() );
        if(iVolume == 0) {
            bEmpty = true;
        }
        else {
            bEmpty = false;
        }

        System.out.println("Empty = " + bEmpty );
        return;
    }
    

    public void Wash() 
    {

        iVolume = 0;
        bEmpty = true;

    }
    

    public void Fill() 
    {

        iFill = getCapacity() - getVolume();    
        iVolume = getVolume() + iFill;
    }
    

    public static void main(String[] args) {
        
        Cup myCup = new Cup();
        myCup.display();
        
    }

}

my liquid container code:

    //Private class

    private int iCapacity;
    private int iVolume;
    private int iTemp;
    private int iFill;
    private String SzMaterial;
    private String SzColor;
    private ContainerColour myColour;

    //Constructor

    public LiquadContainer() 
    {
        reset();

        return;
    }

    //default

    //Specific

    //method

    //Setters

    public void setCapacity(int iValue) 
    {
        iCapacity = iValue; 
    }

    public void setVolume(int iValue) 
    {
        iVolume = iValue;  
    }

    public void setColour(ContainerColour c) 
    {
        myColour = c;
    }

    public void setMaterial(String SzValue) 
    {
        SzMaterial = SzValue;
    }
    
    public void setFill(int iValue) 
    {
        iFill = getVolume() - getCapacity() ;
    }


    //getters

    public int getCapacity()
    {
        return iCapacity;
    }

    public ContainerColour getColour()
    {
        return(this.myColour) ;
    }

    public String getMaterial()
    {
        return SzMaterial ;
    }

    public int getVolume()
    {
        return iVolume ;
    }
    
       public int getFill() 
       {
            iFill = getCapacity() - getVolume();
            return iFill;
       }



    //utilities
    
    
    
      public void fill() 
      {
            iFill = getCapacity() - getVolume();    
            iVolume = getVolume() + iFill;
      }

    public void reset() 
    {
        setCapacity(250);
        setMaterial("ceramic");
        setVolume(200);
        setColour(ContainerColour.BLACK);
    }


    public static void main(String[] args) 
    {
        LiquadContainer myLiquadContainer = new LiquadContainer();

        myLiquadContainer.setCapacity(250);
        myLiquadContainer.setMaterial("ceramic");
        myLiquadContainer.setVolume(200);
        myLiquadContainer.setColour(ContainerColour.BLACK);

        System.out.println(" LiquadContainer Capacity = " + myLiquadContainer.getCapacity() + "\n Volume = " + myLiquadContainer.getVolume() + "\n Color = " + myLiquadContainer.getColour() + "\n Material = " + myLiquadContainer.getMaterial());

    }

>Solution :

All fields of a class are available to all its subclasses (unless they’re private), e.g.

public class LiquidConainer {
    protected int volume;

    public LiquidContainer(int v) {
        volume = v;
    }
}

public class Cup extends LiquidContainer {

    private ContainerColor myColor;

    public Cup(int v, ContainerColor c) {
        super(v);
        myColor = c;
    }

    public void display() {
        System.out.println("Cup: volume = " + volume + ", color = " + color");
    }
}

Volume can be used here, since it is a field of LiquidContainer, and so all subclasses of LiquidContainer can use it as if it was an attribute of their own.

Quick info about visibility keywords:

• private: visible only from the class it belongs to
• protected: visible only from the class it belongs to and its subclasses
• public: visible from anywhere