• Create a new project as SpinnerExample.
• Design the activity_main.xml as follows.

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="hss_24.spinnerexample.MainActivity">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:src="@drawable/simply" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="Please select the item"
        android:textSize="20sp" />

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginTop="10dp">

    </Spinner>
</LinearLayout>

• Code the main java file as follows.

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private Spinner spinner;

    //    Spinner dropdown items
    String[] android_names = {"Cupcake", "Donut", "Eclair", "Froyo", "Ginger Bread", "Honeycomb",
            "IceCream Sandwich", "Jelly Bean", "Kitkat", "Lollipop", "MarshMallow"};

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

        spinner = (Spinner) findViewById(R.id.spinner);

        // create and set adapter for spinner
        final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, android_names);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                // display toast when spinner item is selected
                Toast.makeText(getApplicationContext(), "Selected item is " +
                        parent.getItemAtPosition(position).toString(), Toast.LENGTH_LONG).show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {

            }
        });
    }
}

Run the app and enjoy the output.

Output: