Java tutorial
//package com.java2s; //License from project: Apache License import java.util.UUID; import android.content.Context; import android.content.SharedPreferences; import android.content.SharedPreferences.Editor; public class Main { private static String uniqueID = null; private static final String PREF_UNIQUE_ID = "PREF_UNIQUE_ID"; public synchronized static String guid(Context context) { if (uniqueID == null) { SharedPreferences sharedPrefs = context.getSharedPreferences(PREF_UNIQUE_ID, Context.MODE_PRIVATE); uniqueID = sharedPrefs.getString(PREF_UNIQUE_ID, null); if (uniqueID == null) { uniqueID = UUID.randomUUID().toString(); Editor editor = sharedPrefs.edit(); editor.putString(PREF_UNIQUE_ID, uniqueID); editor.commit(); } } return uniqueID; } }