public class MainActivity extends AppCompatActivity {
    private int count = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    /**
     * This method is called when the order button is clicked.
     */
    public void submitOrder(View view) {

    }

    /**
     * This method is an increment.
     */
    public void increment(View view) {
        display(++count);
        displayPrice(count*5);
    }

    /**
     * This method is a decrement.
     */
    public void decrement(View view) {
        if (count>0){
            display(--count);
            displayPrice(count*5);
        }
    }

    /**
     * This method displays the given quantity value on the screen.
     */
    private void display(int number) {
        TextView quantityTextView = (TextView) findViewById(R.id.quantity);
        quantityTextView.setText("" + number);
    }

    /**
     * This method displays the given price on the screen.
     */
    private void displayPrice(int number) {
        TextView priceTextView = (TextView) findViewById(R.id.price);
        priceTextView.setText(NumberFormat.getCurrencyInstance().format(number));
    }
}

public class MainActivity extends AppCompatActivity {
    TextView quantityTextView;
    int mCount;
    private int mNumberOfCoffees = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        display(mNumberOfCoffees);
        displayPrice(mNumberOfCoffees * 5);
    }
    public void submitOrder(View view) {
        display(mNumberOfCoffees);
        displayPrice(mNumberOfCoffees * 5);
    }

    /**
     * This method displays the given quantity value on the screen.
     */
    private void display(int number) {
        quantityTextView = findViewById(R.id.countTV);
        quantityTextView.setText("" + number);
    }
    /**
     * This method displays the given price on the screen.
     */
    private void displayPrice(int number) {
        TextView priceTextView = (TextView) findViewById(R.id.priceTV);
        priceTextView.setText(NumberFormat.getCurrencyInstance(Locale.US).format(number));
    }

    public void decrement(View view) {
        if(mNumberOfCoffees > 0){
            mNumberOfCoffees = mNumberOfCoffees - 1;
            quantityTextView = findViewById(R.id.countTV);
            quantityTextView.setText("" + mNumberOfCoffees);
        }
    }

    public void increment(View view) {
        mNumberOfCoffees = mNumberOfCoffees + 1;
        quantityTextView = findViewById(R.id.countTV);
        quantityTextView.setText("" + mNumberOfCoffees);
    }
}

public class MainActivity extends AppCompatActivity {

    private int count = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void submitOrder(View view) {
        displayPrice(count * 5);

    }

    public void countPlus(View view) {
        count++;
        display(count);
    }

    public void countMinus(View view) {

        if(count>1) count--;
        display(count);
    }

    private void display(int number) {
        TextView quantityTextView = (TextView) findViewById(R.id.quantity_text_view);
        quantityTextView.setText("" + number);
    }

    private void displayPrice(int number) {
        TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
        priceTextView.setText(NumberFormat.getCurrencyInstance().format(number));
    }
}