Check if key exists in Shared Preferences

Question

I'm creating Shared Preferences as follows

preferences = getSharedPreferences("text", 0);
final Editor editor = preferences.edit();

String s1 = serverIP.getText().toString();
String s2 = serverPort.getText().toString();
String s3 = syncPass.getText().toString();
String s4 = proxyServer.getText().toString();
String s5 = proxyPort.getText().toString();

editor.putString("SERVERIP", s1);
editor.putString("SERVERPORT", s2);
editor.putString("SYNCPASS", s3);
editor.putString("PROXYSERVER", s3);
editor.putString("PROXYPORT", s3);

and onCreate I want to display the values in a new set of TextViews, but the first time I don't have any values stored in the shared preferences and will get a NULL Pointer exception.

I want to know if there is any built-in method which can check if the SharedPreferences contains any value or not, so that I can check if the key exists and if not, then replace the new set of TextViews with the preferences value.

Answer 1

Try contains(String key) Accorting to the Javadocs,

Checks whether the preferences contains a preference. Returns true if the preference exists in the preferences, otherwise false.

Answer 2

Every method for fetching values from SharedPreferences has default value which is returned in case the key does not exist

preferences = getSharedPreferences("text", 0);
String value = preferences.getString("unknown_key",null);
if (value == null) {
    // the key does not exist
} else {
    // handle the value
}

Answer 3

Try out

 SharedPreferences shf = getSharedPreferences("NAME_SharedPref", MODE_WORLD_READABLE);
    String strPref = shf.getString("SERVERIP", null);

    if(strPref != null) {
    // do some thing

    }