CODEWITHSUNDEEP
android
Joyson
Joyson

Reputation: 1653

Shared preferences in android null pointer exception

I move from Activity A to Activity B by intent.I am storing some values in shared preferences in Activity B.In activity A oncreate() i am fetching the values of the shared preferences to compare with some conditions however it gives me null pointer exception as expected (As i do not go to Activity B).However i want to write a condition to fetch the data from shared preferences if the value is not null.Can some one please say how can i achieve this? Following is my code:

   In Activity B: 
               SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(MerchantLogin.this);
                SharedPreferences.Editor editor = prefs.edit();
                editor.putString("showdialog_login", "dontshow");
                editor.commit();
In Activity A:
            @Override
    protected void onCreate(Bundle savedInstanceState) 
    {

      SharedPreferences prefs =null;
 prefs = PreferenceManager.getDefaultSharedPreferences(LoginScreen.this);
SharedPreferences.Editor editor = prefs.edit();


if ((prefs.getString("showdialog_login", null).equalsIgnoreCase("dontshow")))
{

}
else if((prefs.getString("showdialog_login", null).equalsIgnoreCase("true")))
{

}
else if((prefs.getString("showdialog_login", null).equalsIgnoreCase("dummy")))
{

}
else
{
    editor.putString("showdialog_login", "false");
    editor.commit();
}

    }

However i get error at this line:

if ((prefs.getString("showdialog_login", null).equalsIgnoreCase("dontshow"))).How can i execute this block of code.

Upvotes: 2

Views: 1794

Answers (3)

Zoltán
Zoltán

Reputation: 22156

You should always use the constant as the first argument when comparing using equals, i.e.

"dontshow".equalsIgnoreCase(prefs.getString("showdialog_login", null))

You are getting the NullPointerException because the showdialog_login property is not yet set, i.e. 

prefs.getString("showdialog_login", null)

returns null, because that's what you set the default value to.

Effectively, your condition is thus

null.equalsIgnoreCase("dontshow")

-which naturally ends up in a NullPointerException.

Upvotes: 0

Samadhan Medge
Samadhan Medge

Reputation: 2049

In Activity A: 

 static SharedPreferences prefs;
 @Override
    protected void onCreate(Bundle savedInstanceState) 
    {

      prefs = getSharedPreferences("showdialog_login",0);
      String ss= prefs.getString("showdialog_login", "default");
if ((ss.equalsIgnoreCase("dontshow")))
{

}
else if((ss.equalsIgnoreCase("true")))
{

}
else if((ss.equalsIgnoreCase("dummy")))
{

}
else
{
    editor.putString("showdialog_login", "false");
    editor.commit();
}

    }

Upvotes: 0

Sagar
Sagar

Reputation: 1262

Instead of :

prefs.getString("showdialog_login", null)

Use:

prefs.getString("showdialog_login", "")

Because, if value for "showdialog_login" preference is not set, it will return null value and you might get NPE (Null pointer exception).

Upvotes: 2

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