My Java program for simple button app is not working showing incompatible version v7

Question

I am new to android dev and started learning from udacity course but the java code is not running It is showing errors(picture below). I am new at stack overflow too sorry I don't know how to properly post a question.

the java program(image to know the errors)

https://drive.google.com/file/d/1D-OSZX2oxuRWZD_Yb8x4WWUBhMykWQKq/view?usp=sharing

---

package com.example.justjava;


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

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

    @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) {
        display(1);
    }

    /**
     * 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);
    }
}`

---

the XML code`

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/quantity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Quantity:"
        android:padding="15dp"
        />
    <TextView
        android:id="@+id/quantity_text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="0"
        android:layout_below="@id/quantity"
        android:paddingLeft="30dp"
        />
   <Button
       android:layout_width="wrap_content"
       android:layout_height="50dp"
       android:layout_marginLeft="5dp"
       android:layout_below="@id/quantity_text_view"
       android:onClick="submitOrder"
       android:text="Order"/>

</RelativeLayout>`

---

enter image description here

Answer 1

v7 is no longer supported. Instead of v7 use androidx packages.

import androidx.appcompat.app.AppCompatActivity;