How to Obtain the Phone Number of the Android Phone Programmatically?

0 0 3 minutes read

While creating an android app, many times we need authentication by mobile number. To enhance the user experience, we can auto-detect the mobile number in a mobile system. So let’s start an android project! We will create a button, when clicked it will get a mobile number and display it in TextView.

Step by Step Implementation

Step 1: Create a New Project

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. You can either choose Java or Kotlin Language.

Step 2: Working with the activity_main.xml file

Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Create a TextView to display the mobile number. Below is the code for the activity_main.xml file.

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">
 
    <TextView
        android:id="@+id/phone_number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintHorizontal_bias="0.149"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.292" />
 
    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:backgroundTint="#11FF01"
        android:onClick="GetNumber"
        android:text="Get Mobile Number"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.679"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.499" />
 
</androidx.constraintlayout.widget.ConstraintLayout>

Note: android:backgroundTint used to change the color of the button.

Step 3: Add permission in the manifest file

Now about permission, we are doing detection using the ‘Telephony’ class. You should ask the user for 2 permissions

Read phone state
Read Mobile Numbers

XML

<uses-permission android:name="android.permission.READ_PHONE_NUMBERS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />

Add above code in manifest.xml file. It is mandatory to add above these two lines to obtain the phone numbers.

Now let’s get towards the working of the app.

Step 4: Working with the MainActivity.java file

Go to the MainActivity.java file and refer to the following code. About telephony class: Enables the app to access information about the telephony services on the android device. We can determine telephony services and states, as well as access some types of subscriber information. Below is the code for the MainActivity.java file. Comments are added inside the code to understand the code in more detail.

Java

import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Build;
import android.os.Bundle;
import android.telephony.TelephonyManager;
import android.view.View;
import android.widget.TextView;
 
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
 
import static android.Manifest.permission.READ_PHONE_NUMBERS;
import static android.Manifest.permission.READ_PHONE_STATE;
import static android.Manifest.permission.READ_SMS;
 
public class MainActivity extends AppCompatActivity {
     
    TextView phone_number;
 
    @RequiresApi(api = Build.VERSION_CODES.M)
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        ActionBar actionbar = getSupportActionBar();
        actionbar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#11FF01")));
 
        // Binding views
        phone_number = findViewById(R.id.phone_number);
    }
 
    // Function will run after click to button
    public void GetNumber(View v) {
 
        if (ActivityCompat.checkSelfPermission(this, READ_SMS) == PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, READ_PHONE_NUMBERS) ==
                        PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this,
                READ_PHONE_STATE) == PackageManager.PERMISSION_GRANTED) {
            // Permission check
 
            // Create obj of TelephonyManager and ask for current telephone service
            TelephonyManager telephonyManager = (TelephonyManager) this.getSystemService(Context.TELEPHONY_SERVICE);
            String phoneNumber = telephonyManager.getLine1Number();
 
            phone_number.setText(phoneNumber);
            return;
        } else {
            // Ask for permission
            requestPermission();
        }
    }
 
    private void requestPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            requestPermissions(new String[]{READ_SMS, READ_PHONE_NUMBERS, READ_PHONE_STATE}, 100);
        }
    }
 
    public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
        switch (requestCode) {
            case 100:
                TelephonyManager telephonyManager = (TelephonyManager) this.getSystemService(Context.TELEPHONY_SERVICE);
                if (ActivityCompat.checkSelfPermission(this, READ_SMS) !=
                        PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this,
                        READ_PHONE_NUMBERS) != PackageManager.PERMISSION_GRANTED &&
                        ActivityCompat.checkSelfPermission(this, READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
                    return;
                }
                String phoneNumber = telephonyManager.getLine1Number();
                phone_number.setText(phoneNumber);
                break;
            default:
                throw new IllegalStateException("Unexpected value: " + requestCode);
        }
    }
}

Below is the Kotlin Implementation of above code. Go to the MainActivity.kt file and refer below code.

Kotlin

import android.content.pm.PackageManager
import android.graphics.Color
import android.graphics.drawable.ColorDrawable
import android.os.Build
import android.os.Bundle
import android.telephony.TelephonyManager
import android.view.View
import android.widget.TextView
import androidx.annotation.RequiresApi
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
import com.amangfg.storagefirebase.R
 
class MainActivity : AppCompatActivity() {
    var phone_number: TextView? = null
 
    @RequiresApi(api = Build.VERSION_CODES.M)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val actionbar = supportActionBar
        actionbar!!.setBackgroundDrawable(ColorDrawable(Color.parseColor("#11FF01")))
        // TextView reference
        phone_number = findViewById(R.id.phone_number)
    }
 
    fun GetNumber(v: View?) {
        if (ActivityCompat.checkSelfPermission(
                this,
                permission.READ_SMS
            ) == PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                this,
                permission.READ_PHONE_NUMBERS
            ) ==
            PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                this,
                permission.READ_PHONE_STATE
            ) == PackageManager.PERMISSION_GRANTED
        ) {
            // Permission check
 
            // Create obj of TelephonyManager and ask for current telephone service
            val telephonyManager = this.getSystemService(TELEPHONY_SERVICE) as TelephonyManager
            val phoneNumber = telephonyManager.line1Number
            phone_number!!.text = phoneNumber
            return
        } else {
            // Ask for permission
            requestPermission()
        }
    }
 
    private fun requestPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            requestPermissions(
                arrayOf(
                    permission.READ_SMS,
                    permission.READ_PHONE_NUMBERS,
                    permission.READ_PHONE_STATE
                ), 100
            )
        }
    }
 
    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        when (requestCode) {
            100 -> {
                val telephonyManager = this.getSystemService(TELEPHONY_SERVICE) as TelephonyManager
                if (ActivityCompat.checkSelfPermission(this, permission.READ_SMS) !=
                    PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                        this,
                        permission.READ_PHONE_NUMBERS
                    ) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                        this,
                        permission.READ_PHONE_STATE
                    ) != PackageManager.PERMISSION_GRANTED
                ) {
                    return
                }
                val phoneNumber = telephonyManager.line1Number
                phone_number!!.text = phoneNumber
            }
            else -> throw IllegalStateException("Unexpected value: $requestCode")
        }
    }
}