How to get unique device hardware id in Android?

How to get the unique device ID in Android which cannot be changed when performing a phone reset or OS update?

Answer

Update: 19 -11-2019

The below answer is no more relevant to present day.

So for any one looking for answers you should look at the documentation linked below

https://developer.android.com/training/articles/user-data-ids

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Old Answer - Not relevant now.
You check this blog in the link below

http://android-developers.blogspot.in/2011/03/identifying-app-installations.html

ANDROID_ID

import android.provider.Settings.Secure;

private String android_id = Secure.getString(getContext().getContentResolver(),

                                                    Secure.ANDROID_ID); 

The above is from the link @ Is there a unique Android device ID?

More specifically, Settings.Secure.ANDROID_ID. This is a 64-bit quantity that is generated and stored when the device first boots. It is reset when the device is wiped.

ANDROID_ID seems a good choice for a unique device identifier. There are downsides: First, it is not 100% reliable on releases of Android prior to 2.2 (“Froyo”). Also, there has been at least one widely-observed bug in a popular handset from a major manufacturer, where every instance has the same ANDROID_ID.

The below solution is not a good one coz the value survives device wipes (“Factory resets”) and thus you could end up making a nasty mistake when one of your customers wipes their device and passes it on to another person.

You get the imei number of the device using the below

  TelephonyManager telephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
  telephonyManager.getDeviceId();

http://developer.android.com/reference/android/telephony/TelephonyManager.html#getDeviceId%28%29

Add this is manifest