Add to MainActivity.java

Calculate price method

/**
 * Calculates the price of the order.
 * 
 * @param quantity is the number of cups of coffee ordered
 */
private void calculatePrice(int quantity) {
    int price = quantity * 5;
}

Can someone help me please i have a problem when i press run the program give me error select android SDK !!!!

answer 1
int numberOfCoffees =0;int price=0;
public void submitOrder(View view) {
calculatePrice(numberOfCoffees);
String PriceMessge="Total: $"+price+ " \nThank You!";
displayMessage(PriceMessge);
}

/**
 * Calculates the price of the order.
 *
 * @param quantity is the number of cups of coffee ordered
 */
private int calculatePrice(int quantity) {
     price = quantity * 5;
    return price;
}

===============================================================
answer 2
int numberOfCoffees =0;int price=0;
public void submitOrder(View view) {
calculatePrice(numberOfCoffees,10);
String PriceMessge="Total: $"+price+ " \nThank You!";
displayMessage(PriceMessge);
}

/**
 * Calculates the price of the order.
 *
 * @param quantity is the number of cups of coffee ordered
 */
private int calculatePrice(int quantity,int prix) {
     price = quantity * prix;
    return price;
}

===========================================
answer 3
int numberOfCoffees =0;int price=0;
public void submitOrder(View view) {
calculatePrice();
String PriceMessge="Total: $"+price+ " \nThank You!";
displayMessage(PriceMessge);
}

/**
 * Calculates the price of the order.
 *
 * @param price is the number of cups of coffee ordered
 */
private int calculatePrice() {
     price = numberOfCoffees * 5;
    return price;
}

please help me
I can not find the just java app code to solve this test

I declared quantity as a global variable that is updated with increment and decrement buttons......

public void submitOrder(View view) {
    displayMessage(calculatePrice(quantity));
}

@org.jetbrains.annotations.NotNull
private String calculatePrice(int quantity){
    return priceMessage + "\n" + NumberFormat.getCurrencyInstance().format(quantity * pricePerCup);
}

where to find the new code of the project of this course? as submitOrder..etc?

public int displayQuantityA(int quantity,int price_of_per_coffee) {
int calculate = quantity * price_of_per_coffee;
return calculate;
}

public int displayQuantityB() {
int calculate = quantity * 5;
return calculate;
}

public int displayQuantityB() {
int calculate = quantity * 5;
return calculate;
}

public void submitOrder(View view) {
String priceMessage = "Free";
displayMessage(priceMessage);
}