Custom Spinner Using Base Adapter | Android Studio 2021

- Create a new android project named Spinner.

- Create a user model class User.java. Open the User.java file and edit the file as given below.

package com.example.spinner;

public class User {
    int id;
    String name;

    public User() {
    }

    public User(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

- Edit your activity_main.xml file as below to create a spinner.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".MainActivity"
    android:orientation="vertical"
    android:padding="16dp"
    >

   <Spinner
       android:id="@+id/spinner"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       />

</LinearLayout>

- Open your MainActivity.java class and edit as below.

package com.example.spinner;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

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

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

//        create array list of user model
        ArrayList<User> userList = new ArrayList<>();
//        adding element to array list for data

        userList.add(new User(100,"John"));
        userList.add(new User(101,"Adams"));
        userList.add(new User(102,"Baker"));
        userList.add(new User(103,"Evans"));
        userList.add(new User(104,"Mason"));

//        initialize the adapter class
//        it require context and the arraylist
        Adapter a = new Adapter(this,userList);

//        now set the adapter to spinner to populate data
        spinner.setAdapter(a);

//        add a select listener to check which item is selected
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
//                this selected method provide the id from the adapter class
//                we are toasting the id of selected item
                Toast.makeText(getApplicationContext(), "Item at position "+id+" is selected",
                        Toast.LENGTH_SHORT).show();

            }

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

            }
        });
    }

//    lets run a check the app
}

- create a new class Adapter.java and edit the code as below

package com.example.spinner;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.TextView;

import androidx.annotation.NonNull;

import java.util.ArrayList;

public class Adapter extends BaseAdapter {

    Context mContext;
    ArrayList<User> userList;

    public Adapter(Context mContext, ArrayList<User> userList) {
        this.mContext = mContext;
        this.userList = userList;
    }

    @Override
    public int getCount() {
        return userList.size();
    }

    @Override
    public Object getItem(int position) {

        return userList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return userList.get(position).id;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if(convertView==null){
            convertView = LayoutInflater.from(mContext).inflate(R.layout.layout_spinner,null,false);
            TextView textView = convertView.findViewById(R.id.text);

            textView.setText(userList.get(position).getName());
        }


        return convertView;
    }
}

this adapter class help us to populate the data into the spinner.

- create a layout file name layout_spinner.xml and edit the file as below.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >

    <TextView
        android:id="@+id/text"
        android:text="Text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textSize="22sp"
        />

</LinearLayout>

- follow each step carefully and do check for errors in the file then run the application.

Video Tutorial Link

https://www.youtube.com/watch?v=cSTYxCb7NmY