Question

Assume that I have login to system using PHP + MySQL, then, after I exit the apps, I run the apps again, no need to login again and auto login, Please help to solve the problem.

Answer 1

while first time login u get something username or userid in respones than store ther username or userid in sharedpreference like as shown below

  SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(YourActivity.this);

  prefs.edit().putInt("userid",userid).commit();

as after succesfull login this will store your userid in preference and u can check u are already login or not as

int Userid;
prefs = PreferenceManager.getDefaultSharedPreferences(YourActivity.this);
Userid= mPrefs.getInt("userid", 0);  which will return defalut value 0 if u are not login 

after check

 if(Userid>0){
  // Means  u are already logged in  do here code what u want if u are login 
  }else{
    // Means  u are not logged in than go to your login pageview from here
 }

this is just simple way for doing what u want suppose if u want logoout functionality on button click than onclick event u have to add following code for logout which will clear prefernce

 prefs = PreferenceManager.getDefaultSharedPreferences(MyAccountActivity.this);
 prefs.edit().clear().commit();