<!--Permissions for internet-->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<?xml version="1.0" encoding="utf-8"?>
<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:orientation="vertical"
    tools:context=".MainActivity">

    <!--Edittext for getting course Name-->
    <EditText
        android:id="@+id/idEdtCourseName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="10dp"
        android:hint="Course Name"
        android:importantForAutofill="no"
        android:inputType="text" />

    <!--Edittext for getting course Duration-->
    <EditText
        android:id="@+id/idEdtCourseDuration"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="10dp"
        android:hint="Course Duration in min"
        android:importantForAutofill="no"
        android:inputType="time" />

    <!--Edittext for getting course Description-->
    <EditText
        android:id="@+id/idEdtCourseDescription"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="10dp"
        android:hint="Course Description"
        android:importantForAutofill="no"
        android:inputType="text" />

    <!--Button for adding your course to Firebase-->
    <Button
        android:id="@+id/idBtnSubmitCourse"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:text="Submit Course Details"
        android:textAllCaps="false" />

</LinearLayout>

public class Courses {

    // variables for storing our data.
    private String courseName, courseDescription, courseDuration;

    public Courses() {
        // empty constructor
        // required for Firebase.
    }

    // Constructor for all variables.
    public Courses(String courseName, String courseDescription, String courseDuration) {
        this.courseName = courseName;
        this.courseDescription = courseDescription;
        this.courseDuration = courseDuration;
    }

    // getter methods for all variables.
    public String getCourseName() {
        return courseName;
    }

    public void setCourseName(String courseName) {
        this.courseName = courseName;
    }

    public String getCourseDescription() {
        return courseDescription;
    }

    // setter method for all variables.
    public void setCourseDescription(String courseDescription) {
        this.courseDescription = courseDescription;
    }

    public String getCourseDuration() {
        return courseDuration;
    }

    public void setCourseDuration(String courseDuration) {
        this.courseDuration = courseDuration;
    }
}

import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.firestore.CollectionReference;
import com.google.firebase.firestore.DocumentReference;
import com.google.firebase.firestore.FirebaseFirestore;

public class MainActivity extends AppCompatActivity {

    // creating variables for our edit text
    private EditText courseNameEdt, courseDurationEdt, courseDescriptionEdt;

    // creating variable for button
    private Button submitCourseBtn;

    // creating a strings for storing
    // our values from edittext fields.
    private String courseName, courseDuration, courseDescription;

    // creating a variable
    // for firebasefirestore.
    private FirebaseFirestore db;

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

        // getting our instance
        // from Firebase Firestore.
        db = FirebaseFirestore.getInstance();

        // initializing our edittext and buttons
        courseNameEdt = findViewById(R.id.idEdtCourseName);
        courseDescriptionEdt = findViewById(R.id.idEdtCourseDescription);
        courseDurationEdt = findViewById(R.id.idEdtCourseDuration);
        submitCourseBtn = findViewById(R.id.idBtnSubmitCourse);

        // adding on click listener for button
        submitCourseBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                // getting data from edittext fields.
                courseName = courseNameEdt.getText().toString();
                courseDescription = courseDescriptionEdt.getText().toString();
                courseDuration = courseDurationEdt.getText().toString();

                // validating the text fields if empty or not.
                if (TextUtils.isEmpty(courseName)) {
                    courseNameEdt.setError("Please enter Course Name");
                } else if (TextUtils.isEmpty(courseDescription)) {
                    courseDescriptionEdt.setError("Please enter Course Description");
                } else if (TextUtils.isEmpty(courseDuration)) {
                    courseDurationEdt.setError("Please enter Course Duration");
                } else {
                    // calling method to add data to Firebase Firestore.
                    addDataToFirestore(courseName, courseDescription, courseDuration);
                }
            }
        });
    }

    private void addDataToFirestore(String courseName, String courseDescription, String courseDuration) {

        // creating a collection reference
        // for our Firebase Firetore database.
        CollectionReference dbCourses = db.collection("Courses");

        // adding our data to our courses object class.
        Courses courses = new Courses(courseName, courseDescription, courseDuration);

        // below method is use to add data to Firebase Firestore.
        dbCourses.add(courses).addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
            @Override
            public void onSuccess(DocumentReference documentReference) {
                // after the data addition is successful
                // we are displaying a success toast message.
                Toast.makeText(MainActivity.this, "Your Course has been added to Firebase Firestore", Toast.LENGTH_SHORT).show();
            }
        }).addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                // this method is called when the data addition process is failed.
                // displaying a toast message when data addition is failed.
                Toast.makeText(MainActivity.this, "Fail to add course \n" + e, Toast.LENGTH_SHORT).show();
            }
        });
    }
}