How to access unique Android device ID?

If you want to check unique device id like IMEI number through programmatically we can do this by telephonic manger as shown below example −

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version = "1.0" encoding = "utf-8"?>
<android.support.constraint.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">
   <Button
   android:id = "@+id/button"
   android:layout_width = "wrap_content"
   android:layout_height = "wrap_content"
   android:text = "Click here to hide"
   app:layout_constraintBottom_toBottomOf = "parent"
   app:layout_constraintLeft_toLeftOf = "parent"
   app:layout_constraintRight_toRightOf = "parent"
   app:layout_constraintTop_toTopOf = "parent" />
</android.support.constraint.ConstraintLayout>

Step 3 − Add the following code to src/MainActivity.java

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.ProgressDialog;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.support.annotation.RequiresApi;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.telephony.TelephonyManager;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
   TelephonyManager telephonyManager;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      Button button = findViewById(R.id.button);
      button.setOnClickListener(this);
   }
   @RequiresApi(api = Build.VERSION_CODES.O)
   @Override
   public void onClick(View v) {
      switch (v.getId()) {
         case R.id.button:
         deviceId();
         break;
      }
   }
   private void deviceId() {
      telephonyManager = (TelephonyManager) getSystemService(this.TELEPHONY_SERVICE);
      if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
         ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_PHONE_STATE}, 101);
         return;
      }
   }
   @Override
   public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults){
      switch (requestCode) {
         case 101:
         if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
               ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_PHONE_STATE}, 101);
               return;
            }
            String imeiNumber = telephonyManager.getDeviceId();
            Toast.makeText(MainActivity.this,imeiNumber,Toast.LENGTH_LONG).show();
         } else {
            Toast.makeText(MainActivity.this,"Without permission we check",Toast.LENGTH_LONG).show();
         }
         break;
         default:
         super.onRequestPermissionsResult(requestCode, permissions, grantResults);
      }
   }
}

In the above code, we have given runtime permission to read phone state, without phone state we can't get device id. For device id, add the following code in your project.

TelephonyManager telephonyManager;
telephonyManager = (TelephonyManager) getSystemService(this.TELEPHONY_SERVICE);
String imeiNumber = telephonyManager.getDeviceId();

Step 4 − Add the following code to AndroidManifest.xml

<manifest xmlns:android = "http://schemas.android.com/apk/res/android"
package = "com.example.andy.myapplication">
   <uses-permission android:name = "android.permission.READ_PHONE_STATE" />
   <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>

In the above code we have declare Read phone state permission. it going to read all phone states.

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen