How Can I list all mobile contacts on an App Android

Question

I started to learn Mobile App Development with Android Studios. I want to create a simple app(for testing) where I display all cellphone contacts in a ListView.

I have the main activity and its xml file where I have added a ListView element, I want to display all contacts there.

This is the code of the main activity class:

package com.example.contactlist;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
   }
}

this is the code of the main activity 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<androidx.appcompat.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="66dp"
    android:background="@color/colorPrimaryDark"
    android:minHeight="?attr/actionBarSize"
    android:theme="?attr/actionBarTheme"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:title="Contact Lists" />

<TextView
    android:id="@+id/subtitulo_container"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Contact Lists"
    android:textColor="@android:color/black"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintHorizontal_bias="0.087"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.119" />

<ListView
    android:id="@+id/listado_contactos"
    android:layout_width="346dp"
    android:layout_height="644dp"
    android:layout_marginStart="24dp"
    android:layout_marginLeft="24dp"
    android:layout_marginTop="21dp"
    android:layout_marginEnd="23dp"
    android:layout_marginRight="23dp"
    android:layout_marginBottom="29dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/subtitulo_container"
    tools:listitem="@android:layout/simple_list_item_multiple_choice" />

 </androidx.constraintlayout.widget.ConstraintLayout>

and this is the code of the AndroidManifest file:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.contactlist">
<uses-permission android:name="android.permission.READ_CONTACTS"/>
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

</manifest>

What I want to know is how can I get all contacts data from the cellphone and display them in my ListView?

Answer 1

I've developed a utility class to retrieve device contacts. It's available on GitHub:

ContactUtils.kt

Since handling all situations that might happen in retrieving contacts is a bit time consuming, I suggest you get this file and add it to your project. It's written in kotlin, but if you are using java, also it's possible to get the list of contacts like the following:

List<ContactData> contacts = ContactUtilsKt.retrieveAllContacts(context);

// or to retrieve all contacts matching specific search pattern:
List<ContactData> contacts = ContactUtilsKt.retrieveAllContacts(context, "John");