MainActivity.java

package com.example.android.justjava;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.TextView;

import java.text.NumberFormat;

/**
 * This app displays an order form to order coffee.
 */
public class MainActivity extends ActionBarActivity {

    int quantity = 2;

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

    /**
     * This method is called when the plus button is clicked.
     */
    public void increment(View view) {
        quantity = quantity + 1;
        display(quantity);
    }

    /**
     * This method is called when the minus button is clicked.
     */
    public void decrement(View view) {
        quantity = quantity - 1;
        display(quantity);
    }

    /**
     * This method is called when the order button is clicked.
     */
    public void submitOrder(View view) {
        int quantity = 5;
        display(quantity);
        displayPrice(quantity * 5);
    }

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

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

}

package com.example.justjava;

import android.R
import android.os.Bundle
import android.view.View
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import java.text.NumberFormat

/**

This app displays an order form to order coffee.
*/
class MainActivity : AppCompatActivity() {

var quantity = 0

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(com.example.justjava.R.layout.activity_main)
}

/**
 * This method is called when the PLUS button is clicked.
 */
fun increment (view: View?) {
    quantity = quantity + 1
    display(quantity)
}

/**
 * This method is called when the MINUS button is clicked.
 */
fun decrement (view: View?) {
    quantity = quantity - 1
    display(quantity)
}

/**
 * This method is called when the ORDER button is clicked.
 */
fun submitOrder(view: View?) {
    display(quantity)
    displayPrice(quantity * 50)
}

/**
 * This method displays the given quantity value on the screen.
 */
private fun display(number: Int) {
    val quantityTextView = findViewById<View>(com.example.justjava.R.id.quantity_text_view) as TextView
    quantityTextView.text = "" + number
}

/**
 * This method displays the given price on the screen.
 */
private fun displayPrice(number: Int) {
    val priceTextView = findViewById<View>(com.example.justjava.R.id.price_text_view) as TextView
    priceTextView.setText(NumberFormat.getCurrencyInstance().format(number))
}

}

CAN YOU PROVIDE ME THE XML CODE MY XML CODE HAS SOME ERROR

package com.example.myapplication2;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import java.text.NumberFormat;
public class MainActivity extends AppCompatActivity {
int quantity=2;
@OverRide
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void decrement(View view)
{
quantity = quantity - 1;
display(quantity);
}
public void increment(View view)
{
quantity = quantity + 1;
display(quantity);
}
public void submitOrder(View view){
display(quantity);
displayPrice(quantity*5);
}
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);
priceTextView.setText(NumberFormat.getCurrencyInstance().format(number));
}

}