i create app where when user added new data , there is new label
I have tried and it worked, but I wonder how can I make the json that I store in SharedPreferences
do not over write
so I can add 2 or more user json to adapter
Here is my put string file the json variable contain user that added
SharedPreferences sharedPreferences = getSharedPreferences("newUser", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("listNewUser",json)
editor.apply();
Here is how I can get json from shared preference
try{
String listNewUserAdd = sh.getString("listNewUser","");
JSONObject object = new JSONObject(listNewUserAdd);
for (int i=0; i<object.length(); i++) {
CustomerNew customer = new CustomerNew();
customer.setCustomerName(object.getString("receiverName"));
customer.setAccountId(object.getString("customerReference"));
customer.setId(object.getLong("customerId"));
System.out.println("### GET CUSTOMER NAME "+customer.getCustomerName());
listSortNew.add(customer);
if (listSortNew == null) {
// if the array list is empty
// creating a new array list.
listSortNew = new ArrayList<>();
}
}
I think there are two ways to realize it. One way is when you put data you have to check if it exists.
SharedPreferences sharedPreferences = getSharedPreferences("newUser", MODE_PRIVATE);
String listNewUser = sharedPreferences.getString("listNewUser","");
if(!TextUtils.isEmpty(listNewUser)){
//covert it the list object
//then add the all new item to it
//finally convert it to json string
}
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("listNewUser",json)
editor.apply();
the other way is to change the SharedPreferences MODE_APPEND
but you must know, it doesn't mean that you add multiple values for each key. It means that if the file already exists it is appended to and not erased. We usually used MODE_PRIVATE
In the end I suggest you firstly get the data from it, then check if you need change, you can change the data, then save it again.
Related
Please be patient while I explain my issue:
1) I am storing my preferences via a StringSet as follows:
SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE).edit();
// Create a new Arraylist with the details of our details
ArrayList <String> newCityFareDetails = new ArrayList<String>();
// Store various values
newCityFareDetails.add(0, String.valueOf(cloneFare.value1()));
newCityFareDetails.add(1, String.valueOf(cloneFare.value2()));
newCityFareDetails.add(2, String.valueOf(cloneFare.value3()));
newCityFareDetails.add(3, String.valueOf(cloneFare.value4()));
newCityFareDetails.add(4, cloneFare.value5());
// Only value 5 is a string, rest are all floats
// Convert to a hashstring, give it the name of our value
Set<String> set = new HashSet<String>();
set.addAll(newCityFareDetails);
editor.putStringSet(extras.getString("startCity"), set);
// And write it to storage
editor.commit();
Now, I'm trying to read it as follows:
SharedPreferences prefs = getSharedPreferences(MY_PREFS_NAME, Context.MODE_PRIVATE);
Set<String> tryCityFromPrefs = prefs.getStringSet(currentCity, null);
if (tryCityFromPrefs!=null){
// Crude code, but we convert the preferences into a String array
String[] values = tryCityFromPrefs.toArray(new String[tryCityFromPrefs.size()]);
myFare = new Fare(Float.parseFloat(values[0]), Float.parseFloat(values[1]),
Float.parseFloat(values[2]), Float.parseFloat(values[3]), values[4]);
}
Now, problem is that the myFare is not getting initialized properly because the values in the array are scrambled. i.e. the String value that was at the last position when we save is now in the 2nd position. Is this something to do with Sets to String conversion? Or am I missing something obvious?
A Set does not guarantee order. While there are specific Set implementations (e.g., LinkedHashSet) that are ordered, that's not what SharedPreferences uses.
Your options are:
Change your app to not care about the order.
Save the data in SharedPreferences some other way. In this app, for example, I use JsonReader/JsonWriter to save an ArrayList into a single String value.
Save the data in some other fashion (e.g., JSON file, SQLite database with a sequence number to maintain order).
I want to store an ArrayList<class> in shared preference. But the error showed up in editor3.putString("Array", nama);. I guess the error caused by putString. What sould i do?
Should I used another method to storing arraylist ?
ArrayList<Class> nama = new ArrayList<Class>(9);
nama.add(dragsandal.class);nama.add(Terimakasih.class);
nama.add(Ludah.class);
nama.add(Permisi.class);
nama.add(Tolong.class);
nama.add(Maaf.class);
SharedPreferences pref3 = getApplicationContext().getSharedPreferences("Array", MODE_PRIVATE);
SharedPreferences.Editor editor3 = pref3.edit();
editor3.putString("Array", nama);
editor3.apply();
You should use putStringSet(Set<String>) to store sets (Lists with unique elements). SharedPreferences do not provide a method to store lists directly.
You can easily convert your list to a set using e.g. new HashSet<String>(yourList);
If you need to store a list, you can serialize your list to a String, e.g. by using Gson and storing the json value. Then putString(json) would be correct.
First I don't think there is a way to store lists in Shared preferences. Second it is not a good idea. In your case,I would consider using Sqlite database. It would make things easier.
You can't store a Class type object in SharedPreferences. Also you can't store Lists. If you really need to, you can store the full name of the class object as a String. Then when you read the value back you, you can use Class.forName() to convert that string back to a class. It seems weird, but you can do it.
You could try this to save and restore a set of class names:
Set<String> set = new HashSet<String>();
set.put(Terimakasih.class.getName());
set.put(Ludah.class.getName());
set.put(Permisi.class.getName());
set.put(Tolong.class.getName());
set.put(Maaf.class.getName());
SharedPreferences pref3 = getApplicationContext().getSharedPreferences("set", MODE_PRIVATE);
SharedPreferences.Editor editor3 = pref3.edit();
editor3.putStringSet("set", set);
editor3.apply();
Set<String> strings = pref3.getStringSet("set", Collections.emptySet());
Set<Class> classes = new HashSet<Class>();
for (String s : strings) {
classes.put(Class.forName(s));
}
My application is basically a quiz that presents people with world flags. I want to add a save function that adds the current flag to a separate list. Right now, this is what I do when they click the "save" button:
saveListGC.add(playList.get(1));
(playList.get(1) is the current flag). The problem is, I have to re-define the saveListGC every time the script starts, and that empties the contents:
public static ArrayList<String> saveListGC = new ArrayList<String>();
So what I'm wondering is how can I save this data, and re-load it later? I've seen things about using SharedPrefernces, but I don't really understand it. If someone could please explain it as easily as possible, I would really appreciate it. Thank you!
This a simple example of how you can use SharedPreferences:
//intiat your shared pref
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode
Editor editor = pref.edit();
//store data to pref
editor.putString("myString", "value 1");
editor.commit();
//retrieve data from pref
String myString = pref.getString("myString", null);
But the real problem here is that SharedPreferences can not store an Object of type List (ArrayList), but you can store an Object of type Set (like Hashset) using this method
Set<String> mySet = new HashSet<String>();
mySet.add("value1");
mySet.add("value2");
mySet.add("value3");
editor.putStringSet("MySet", mySet);
So to answer your second question, this what i propose for you to do:
//This is your List
ArrayList<String> saveListGC = new ArrayList<String>();
//Convert your List to a Set
Set<String> saveSetGC = new HashSet<String>(saveListGC);
//Now Store Data to the SharedPreferences
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0);
Editor editor = pref.edit();
editor.putStringSet("MySet", saveSetGC);
editor.commit();
//After that in another place or in another Activity , Or every where in your app you can Retreive your List back
pref = getApplicationContext().getSharedPreferences("MyPref", 0);
Set<String> mySetBack = pref.getStringSet("MySet", null);
//Convert Your Set to List again
ArrayList<String> myListBack = new ArrayList<String>(mySetBack);
//Here you can se the List as you like...............
Log.i("MyTag", myListBack.get(0));
Log.i("MyTag", myListBack.get(1));
Good Luck :)
I save a string set in the shared preferences, if I read it out it's ok. I start other activities, go back and read it again, it's ok. If I close the application, and start it again, I get the set, but with only 1 item instead of 4. It happens all the time. Is there a known issue? What could I do wrong?
In a class, what is created in the application's oncreate method I have a SharedPreferences and a SharePreferences.Editor variable. I use them in the save and load methods.
public void saveFeedback(FeedbackItem feedbackItem) {
checkSp();
Set<String> feedbackSet = getFeedbacksSet();
if(feedbackSet == null){
feedbackSet = new HashSet<String>();
}
JSONObject json = createJSONObjectfromFeedback(feedbackItem);
feedbackSet.add(json.toString());
ed.putStringSet(CoreSetup.KEY_FEEDBACK, feedbackSet);
ed.commit();
}
public Set<String> getFeedbacksSet(){
checkSp();
Set<String> ret = sp.getStringSet(CoreSetup.KEY_FEEDBACK, null);
return ret;
}
private void checkSp(){
if(this.sp == null)
this.sp = applicationContext.getSharedPreferences(applicationContext.getPackageName(), Context.MODE_PRIVATE);
if(this.ed == null)
this.ed = this.sp.edit();
}
I just can't understand how could it happen, to store perfectly all items while the app is running, then after a restart not all items are in the set. And I think if all items are removed it could be more acceptable than some items are gone, and one item is still there. Is there an explanation?
Based on your question, you should call commit only after 4 items have been added to the set.
In your code, you are calling commit for each feedback which will overwrite the previous feedback.
Update:
http://developer.android.com/reference/android/content/SharedPreferences.html#getStringSet(java.lang.String, java.util.Set)
Note that you must not modify the set instance returned by this call. The consistency of the stored data is not guaranteed if you do, nor is your ability to modify the instance at all.
This is exactly what you are doing
This "problem" is documented on SharedPreferences.getStringSet().
getStringSet() returns a reference of the stored HashSet object inside SharedPreferences. When you add elements to this object, they are added in fact inside SharedPreferences.
The workaround is making a copy of the returned Set and putting the new Set into SharedPreferences. I tested it and it works.
In Kotlin, that would be
val setFromSharedPreferences = sharedPreferences.getStringSet("key", mutableSetOf())
val copyOfSet = setFromSharedPreferences.toMutableSet()
copyOfSet.add(addedString)
val editor = sharedPreferences.edit()
editor.putStringSet("key", copyOfSet)
editor.apply() // or commit() if really needed
Try to create Copy of your set, and than you can save it in same prefs:
private Set<String> _setFromPrefs;
public void GetSetFromPrefs()
{
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
Set<String> someSets = sharedPref.getStringSet("some_sets", new HashSet<String>() );
_setFromPrefs = new HashSet<>(someSets); // THIS LINE CREATE A COPY
}
public void SaveSetsInPrefs()
{
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
SharedPreferences.Editor editor = sharedPref.edit();
editor.putStringSet("some_sets", _setFromPrefs);
editor.commit();
}
Ran into this same problem. Solved it by clearing the editor after instantiating and before committing.
sPrefs = PreferenceManager.getDefaultSharedPreferences(context);
sFavList = sPrefs.getStringSet(context.getResources().getString(R.string.pref_fav_key), null);
sEditor = sPrefs.edit();
sEditor.clear(); // added clear, now Set data persists as expected
if (sFavList == null) sFavList = new HashSet<>();
sFavList.add(title);
sEditor.putStringSet(context.getResources().getString(R.string.pref_fav_key), sFavList).apply();
I tried creating a copy as others suggested, but that didn't work for me.
Found this solution here.
According to the document, the String Set in SharedPreferences should treated as immutable, things go south when trying to modify it. A work around would be:
Get the existing set, make a copy of it, update the copy and then save it back to the shared preferences like it was a new set.
Set<String> feedbackSet = getFeedbacksSet();
if(feedbackSet == null){
feedbackSet = new HashSet<String>();
}
//make a copy of the set, update the copy and save the copy
Set<String> newFeedbackSet = new HashSet<String>();
JSONObject json = createJSONObjectfromFeedback(feedbackItem);
newFeedbackSet.add(json.toString());
newFeedbackSet.addAll(feedbackSet);
ed.putStringSet(CoreSetup.KEY_FEEDBACK, newFeedbackSet);
ed.commit();
public void saveFeedback(FeedbackItem feedbackItem) {
checkSp();
Set<String> feedbackSet = getFeedbacksSet();
if(feedbackSet == null){
feedbackSet = new HashSet<String>();
}
JSONObject json = createJSONObjectfromFeedback(feedbackItem);
feedbackSet.add(json.toString());
ed.putStringSet(CoreSetup.KEY_FEEDBACK, null);
ed.commit();
ed.putStringSet(CoreSetup.KEY_FEEDBACK, feedbackSet);
ed.commit();
}
To save string in sharedprefernces
SharedPreferences.Editor editor = PreferenceManager.getDefaultSharedPreferences(this).edit();
editor.putString("text", mSaved.getText().toString());
editor.commit();
To retrieve data from shared preference
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
String restoredText = prefs.getString("text", null);
I have an ArrayList that can contain 1 to 15 strings. Those strings need to be saved in my shared preferences, now I know how to iterate trough the array to get the strings. What I don't know, is there a clean way to dynamically add the strings to my shared preferences file? I could do this on a sluggish way by creating 15 strings and using an if statement to fill the shared preference, but I would like to know if there is a better way.
Thank you.
If its about naming, you can use something like this:
public static final String mPrefix = "mArray";
SharedPreferences prefs;
prefs = this.getSharedPreferences("PREF", 0);
prefsEditor = appSharedPrefs.edit();
//mAL is your ArrayList
for(int i=0; i<mAl.size(); i++){
prefsEditor.putString(mPrefix + "-" + i, mAl.get(i));
}
prefsEditor.commit();
You can use the putStringSet method available in SharedPreferences.Editor to store string arrays. For example:
String[] array = new String[]{"this", "is", "a", "string", "array"};
SharedPreferences.Editor edit = sharedPrefs.edit();
edit.putStringSet("myKey", new HashSet<String>(Arrays.asList(array)));
edit.commit();
Or if your API is below 11 then you may convert your string array into a single string and save it just like an ordinary string. For example:
edit.putString("myKey", TextUtils.join(",", array));
and later use the following to rebuild your array from string:
array = TextUtils.split(sharedPrefs.getString("myKey", null), ",");
Mainly to edit the shared prefernces data you need to take the Editor Object from it so you could edit it freely so to put data in it:
SharedPrefernces preferences = mContext.getSharedPreferences(MODE_PRIVATE);
Editor prefEditor = preferences.edit();
prefEditor.putString("this is a key object","this is value of the key");
You can also put inside different kinds of object for example : boolean , int , float , double and etc....
Just look up the editor class in android developers website...
In order to read the data from the sharedPrefrences it is even more simplier
SharedPrefrences pref = mContext.getSharedPreferences(MODE_PRIVATE);
pref.getString("the key of the value");