A Stimulation of an Inventory

import java.util.Scanner;
class MyInventory{
    int id[] = new int[30];
    String name[] = new String[30];
    int quantity[] = new int[30];
    int count = 0;
}
interface AddItem{
    public void addItem(String name);
    public void addItem(int qty);
    public void addItem(int qty, int id);
}
interface RemoveItem{
    public void delete(int id);
}
interface DisplayItems{
    public void displayAll();
    public void display();
    public void displayQuantity(int id);
}
class Inventory{
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        while(true){
            System.out.println("\n1.Log in as Manager\n2.Exit");
            switch(sc.nextInt()){
                case 1 :
                    System.out.print("Enter your password: ");
                    if("S22".equals(sc.next()))
                        new Manager().call();
                    else System.out.println("Wrong Password.");
                    break;
                case 0:
                    return;
            }
        }
    }
}
class Manager extends MyInventory implements AddItem,RemoveItem,DisplayItems{
    public void addItem(String n){
        name[count] = n;
    }
    public void addItem(int qty){
        quantity[count] = qty;
    }
    public void addItem(int qty, int count){
        quantity[count]+=qty;
    }
    public void delete(int count){
        quantity[count]=0;
    }
    public void displayAll(){
        System.out.println("ID\tNAME\tQUANTITY");
        for(int i=0;i<count;i++)
            System.out.println(+id[i]+"\t"+name[i]+"\t"+quantity[i]);
    }
    public void display(){
        System.out.println("ID\tNAME\tQUANTITY");
        for(int i=0;i<count;i++)
            if(quantity[i]!=0)
                System.out.println(+id[i]+"\t"+name[i]+"\t"+quantity[i]);
    }
    public void displayQuantity(int id){
        System.out.println("ID\tNAME\tQUANTITY");
        System.out.println(+id+" \t"+name[id]+"\t"+quantity[id]);
    }
    void call(){
        Scanner sc = new Scanner(System.in);
        int quan,id;
        String name;
        while(true){
            System.out.println("\n1.New Item 2.Remove Item 3.Display Items in Stock\n4.Display All Items 5.Update Quantity 6.Display Quantity\n0.Log out");
            int choice = sc.nextInt();
            switch(choice){
            case 1:
                    System.out.print("Name of new item: ");
                    addItem(sc.next());
                    System.out.print("Enter the quantity of the new item: ");
                    addItem(sc.nextInt());
                    count++;
                    break;
            case 2:
                    System.out.print("Enter Product Id: ");
                    delete(sc.nextInt());
                    break;
            case 3:
                    display();
                    break;
            case 4:
                    displayAll();
                    break;
            case 5:
                    System.out.print("Enter Product Id: ");
                    id = sc.nextInt();
                    System.out.print("Enter quantity of product: ");
                    quan = sc.nextInt();
                    addItem(quan,id);
                    break;
            case 6:
                    System.out.println("Enter Product Id: ");
                    displayQuantity(sc.nextInt());
                    break;
            case 0: return;
            }
        }
    }
}