Adding layout file to class (Java Android Studio)

Question

When adding an (empty activity), the class generates with the appropriate layout file but in the setContentview(R.layout.activity_home) it gives an error.

This is my (empty) class:

package com.test.learnlogin;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;

public class HomeActivity extends AppCompatActivity {

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

}

And this is the layout file to refer to:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

I am assuming that the name activity_home inside setContentView is of red color.

if yes and you are sure that activity_home file exists in Res > Layout then please Restart Your Android Studio , that All

Answer 2

You'll have to import R to remove that error.

import com.test.R // assuming your_package_name=com.test

at the top.