My AppCompatActivity isn't working. why so?

Question

I was working on a project, following error showed up:

ERROR: Failed to resolve: com.android.support:design:29.3.0 Add Google Maven repository and sync project Show in Project Structure dialog Affected Modules: app ERROR: Failed to resolve: com.android.support:appcompat-v7:29.3.0 Add Google Maven repository and sync project Show in Project Structure dialog Affected Modules: app

Here is the code for the XML:

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/tan_background"
    android:orientation="vertical"
    tools:context="com.example.android.miwok.MainActivity">

    <TextView
        android:id="@+id/numbers"
        style="@style/CategoryStyle"
        android:background="@color/category_numbers"
        android:text="@string/category_numbers" />

    <TextView
        android:id="@+id/family"
        style="@style/CategoryStyle"
        android:background="@color/category_family"
        android:text="@string/category_family" />

    <TextView
        android:id="@+id/colors"
        style="@style/CategoryStyle"
        android:background="@color/category_colors"
        android:text="@string/category_colors" />

    <TextView
        android:id="@+id/phrases"
        style="@style/CategoryStyle"
        android:background="@color/category_phrases"
        android:text="@string/category_phrases" />

</LinearLayout>

And Java:

package com.example.android.myprejoct;

import android.os.Bundle;
import androidx.annotation.*;

public class MainActivity extends AppCompatActivity {

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

What do I do?

Answer 1

Add this line in gradle file

allprojects {
    repositories {
        google()

        // If you're using a version of Gradle lower than 4.1, you must
        // instead use:
        //
        // maven {
        //     url 'https://maven.google.com'
        // }
    }
}

Hope this will work!