If you’re thinking about creating a drop-down list in android, you’ve come to the right place. In this blog post, I will show you how to create a drop-down list in android. I will show you how can you populate the drop-down list with data and how can you handle user selections. So, without further ado, let’s get started!
Actually, I’m using the term drop-down list here, but android doesn’t call it a drop-down list. In the android world, a drop-down list is called a spinner. So, from now on, I will use the term spinner.
How to create a Spinner in android?
I will create a simple app that contains a Spinner and a TextView. The Spinner shows a list of book genres. When I select a genre from the list, it shows the genre in the TextView. First, let’s see the steps, then I will share the full code.
Steps to create the Spinner –
Add the spinner to the XML layout using the <Spinner> element.
<Spinner
android:id="@+id/spinner"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
Now, we have to populate the spinner with a list of items. To do this, first I will specify a string array in the string resource file. I will create the choices for the spinner using this array.
<resources>
<string name="app_name">Spinners_Example</string>
<string-array name="genres_array">
<item>Comic</item>
<item>Romance</item>
<item>Fairytale</item>
<item>Fantasy</item>
<item>Sci-Fi</item>
</string-array>
</resources>
The spinner takes an ArrayAdapter object as a parameter. You can think of it as a holder of the items for the spinner. Let’s create an ArrayAdapter using the string array that I defined in the string resource file.
Spinner spinner = (Spinner) findViewById(R.id.spinner);
// Create an ArrayAdapter for the spinner using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.genres_array, android.R.layout.simple_spinner_item);
// Provide the layout that should be used when the selection list displays.
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// Pass the adapter to the spinner
spinner.setAdapter(adapter);
Here, I created the ArrayAdpater and passed the adapter to the spinner.
Now, I will set the listener to the spinner so that it will respond when a selection is made. In this case, when a selection is made then the choice appears in the text view.
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
// Retrieve the selected item
String selectedItem= (String) adapterView.getSelectedItem();
//show the selected item in the TextView
textView.setText(selectedItem);
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
});
That completes the steps. Now, I will share the full code.
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:id="@+id/constraint_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<Spinner
android:id="@+id/spinner"
android:layout_width="184dp"
android:layout_height="38dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.189"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.261" />
<TextView
android:id="@+id/textView"
android:layout_width="282dp"
android:layout_height="52dp"
android:textSize="18sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.496"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/spinner"
app:layout_constraintVertical_bias="0.202" />
</androidx.constraintlayout.widget.ConstraintLayout>
strings.xml
<resources>
<string name="app_name">Spinners_Example</string>
<string-array name="genres_array">
<item>Comic</item>
<item>Romance</item>
<item>Fairytale</item>
<item>Fantasy</item>
<item>Sci-Fi</item>
</string-array>
</resources>
MainActivity.java
package com.example.spinners_example;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textView = findViewById(R.id.textView);
Spinner spinner = (Spinner) findViewById(R.id.spinner);
// Create an ArrayAdapter for the spinner using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.genres_array, android.R.layout.simple_spinner_item);
// Provide the layout that should be used when the selection list displays.
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// Pass the adapter to the spinner
spinner.setAdapter(adapter);
//Set the listener to the spinner
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
// Retrieve the selected item
String selectedItem= (String) adapterView.getSelectedItem();
//show the selected item in the TextView
textView.setText(selectedItem);
}
@Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
});
}
}
Output:
That completes this post.
Goodbye.
DeveloperXon 
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