How to return a double from SharedPreferences (Android)

Question

I apparently do not have enough reputation to add a comment and request clarification on a topic, so I will have to re-add the question here.

According to the link: Can't put double SharedPreferences

The top rated answer has the best way to return a double from sharedpreferences as:

double getDouble(final SharedPreferences prefs,
                 final String key, final double defaultValue) {
    return Double.longBitsToDouble(prefs.getLong(key, Double.doubleToLongBits(defaultValue)));
}

I am having trouble identifying what goes into the parameter defaultValue. Is this parameter supposed to be a variable doing in (like a double) that the original value was? Is it unique to my class? What is it?

If possible, would someone mind giving an example so I can understand it a bit better?

Thanks!

Ahmad Dwaik 'Warlock' · Accepted Answer · 2014-03-23T10:16:12.617

defaultValue is what you get when there is no such key defined as "key" in shared pref, example if you are retrieving data for first time and you didn't write a value for your key it will return defaultValue.

double getDouble(final SharedPreferences prefs, final String key, final double defaultValue)
{ return Double.longBitsToDouble(prefs.getLong(key, Double.doubleToLongBits(defaultValue)));}

lets say you have put 542.3 into myDouble

getDouble("myDouble" , 5.0); // will return 542.3

but if you haven't put anything into myDouble

getDouble("myDouble" , 5.0); // will return 5

The common use, is when keep track of data, and your users can clear that data (imagine a highscore in a game) so you don't want to check if it exists, instead you launch it with default value.

getDouble("highscore" , 0.0); // will return highscore if exists otherwise will return 0

Flawless answer. Thank you very much sir! – PGMacDesign Mar 23 '14 at 16:13 — PGMacDesign, Mar 23 '14 at 16:13

score 2 · Answer 2 · answered Sep 25 '17 at 14:05

Set and Get preferences as string....

latitude = location.getLatitude();
longitude = location.getLongitude();

//save last valid position
String mLastLatitude = latitude.toString();
myPreferences.setLastLatitude(mLastLatitude);

String mLastLongitude = longitude.toString();
myPreferences.setLastLongitude(mLastLongitude);

//get last position 
lastLatitude = Double.valueOf(myPreferences.getLastLatitude());
lastLongitude = Double.valueOf(myPreferences.getLastLongitude());

How to return a double from SharedPreferences (Android)

2 Answers2