A Great Method Generated By Majid Tunio To Parse FirebaseFirestore Data Into Android Spinner Adapter With Beautiful Way

activity_main.xml

<android.support.constraint.ConstraintLayout 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="pk.jobme.jobmeapp.PostJobActivity">

    <Spinner
        android:id="@+id/job_category_spinner"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        android:prompt="Choose any category"
        android:textSize="16sp" />
  
</android.support.constraint.ConstraintLayout>

Categories.java

/**************************************
*       Categories Object Class       *
***************************************/

/**
 * Created by Majey on 2/18/2018.
 */

public class Categories {
    public String cat_id, cat_name, cat_description, cat_image;

    public Categories(){

    }

    public String getCat_id() {
        return cat_id;
    }

    public void setCat_id(String cat_id) {
        this.cat_id = cat_id;
    }

    public String getCat_name() {
        return cat_name;
    }

    public void setCat_name(String cat_name) {
        this.cat_name = cat_name;
    }

    public String getCat_description() {
        return cat_description;
    }

    public void setCat_description(String cat_description) {
        this.cat_description = cat_description;
    }

    public String getCat_image() {
        return cat_image;
    }

    public void setCat_image(String cat_image) {
        this.cat_image = cat_image;
    }

    public Categories(String cat_id, String cat_name, String cat_description, String cat_image) {
        this.cat_id = cat_id;
        this.cat_name = cat_name;
        this.cat_description = cat_description;
        this.cat_image = cat_image;
    }
}

MajeysFirebaseSpinner.java

/*****************************************
* Majeys Firebase Spinner Activity Class *
******************************************/

/**
 * Created by Majey on 2/18/2018.
 */

public class MajeysFirebaseSpinner extends AppCompatActivity {

    // Firebase FireStore Object Variable
    private FirebaseFirestore firebaseFirestore;

    // Activity Instance Creation 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_post_job);

	// A Great Method Generated By Majid Tunio To Parse FirebaseFirestore Data Into Spinner Adapter With Beautiful Way

	// Instances Of Spinner
	jobCategorySpinner = (Spinner) findViewById(R.id.job_category_spinner);

		// Get Instance Of Firebase FireStore
	firebaseFirestore = FirebaseFirestore.getInstance();

		// Set a final ArrayList for Your Categories Object
		final ArrayList categoriesList = new ArrayList<Categories>();

		// Set a Final ArrayAdapter typeOf ArrayList as spinnerAdapter and add new ArrayAdapter with current Context, Layout and categoriesList
	final ArrayAdapter<ArrayList> spinnerAdapter = new ArrayAdapter<ArrayList>(PostJobActivity.this, android.R.layout.simple_list_item_1, categoriesList);

		// Get Data From Firebase Firestore
	firebaseFirestore.collection("JobCategories").addSnapshotListener(new EventListener<QuerySnapshot>() {
	    @Override
	    public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
		// If any error this will popup a toast including error.
				if(e != null){
		    Toast.makeText(PostJobActivity.this, "Firebase Error: " + e.getMessage(), Toast.LENGTH_SHORT).show();
		}

				// Get all documents from selection of JobCategories
		for (DocumentChange doc : documentSnapshots.getDocumentChanges()){

			// Check If Data Has Been Added Into Document Successfully
			if(doc.getType() == DocumentChange.Type.ADDED) {

			// Store Document Data Object Into Your Categories Object Class
			Categories categories = doc.getDocument().toObject(Categories.class);

			// Add Gotten Object Data Into Your ArrayList And Get Values You Want To Pupulate Into Spinner Items
			categoriesList.add(categories.getCat_name());

			// Notify All Above Changes Into Spinner Adapter
			spinnerAdapter.notifyDataSetChanged();
		    }
		}
	    }
	});

	// Set Firestore Parsed Adapter Into Spinner
	jobCategorySpinner.setAdapter(spinnerAdapter);

	// A Great Method Generated By Majid Tunio To Parse FirebaseFirestore Data Into Spinner Adapter With Beautiful Way

	}
}