Understanding content providers and permissions:
i. Read phonebook contacts using content providers and display in list.


MainActivity.java

package com.example.assignment12;

import androidx.appcompat.app.AppCompatActivity;

import androidx.core.app.ActivityCompat;

import androidx.core.content.ContextCompat;

import android.Manifest;

import android.content.pm.PackageManager;

import android.database.Cursor;

import android.os.Bundle;

import android.provider.ContactsContract;

import android.widget.ArrayAdapter;

import android.widget.ListView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    ListView list;

    ArrayList list1;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        list = (ListView) findViewById(R.id.list);

        list1=new ArrayList();

        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) {

            ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_CONTACTS}, 0);

        } else

            {

            Cursor phones = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME);

            while (phones.moveToNext())

            {

                String name = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));

                String no = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));

                list1.add(name+"\n"+no);

            }

                ArrayAdapter adapter = new ArrayAdapter(MainActivity.this,android.R.layout.simple_list_item_1,list1);

                list.setAdapter(adapter);

        }

    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<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"

    tools:context=".MainActivity">

    <ListView android:id="@+id/list"

        android:layout_height="wrap_content"

        android:layout_width="match_parent">

    </ListView>

</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.assignment12">

    <uses-permission android:name="android.permission.READ_CONTACTS">

    </uses-permission>

    <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>

Output

To download follow this link : Program 12