Can't get IMEI number on first install

Question

I am trying to get the IMEI number of the android device.I am able to get it too, but the application doesn't return the IMEI in the first Install. i need to restart the application. Can anyone tell me where I am Wrong? Thanks in advance

    public class RootActivity extends AppCompatActivity {

    private static final int REQUEST_PERMISSION_PHONE_STATE = 1;
    TextView tv ;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = findViewById(R.id.TV_imei);
        tv.setText(showPhoneStatePermission());

    }private String showPhoneStatePermission() {
        String imei ="ERROR";
        int permissionCheck = ContextCompat.checkSelfPermission(
                this, Manifest.permission.READ_PHONE_STATE);
        if (permissionCheck != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_PHONE_STATE}, REQUEST_PERMISSION_PHONE_STATE);
        } else {
            imei=getIMEI();
        }
        return imei;
    }

    private String  getIMEI() {
        TelephonyManager telephonyManager = (TelephonyManager) getApplicationContext().getSystemService(Context.TELEPHONY_SERVICE);
        @SuppressLint("MissingPermission") String deviceId = telephonyManager.getDeviceId().trim();
        return deviceId;
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        showPhoneStatePermission();
    }

}

Answer 1

tv.setText(showPhoneStatePermission()) will only get called once in OnCreate(). After permission granted in onRequestPermissionsResult you did not set text . You need to cal setText() after onRequestPermissionsResult. You can use

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    tv.setText(showPhoneStatePermission());
}

If this is just a sample then Okay . If not then you are missing Permission handling in your code . You need to handle Rational too . Look at android-m-check-runtime-permission