I am trying to store a Person object with ActiveAndroid. I set the birthdate like this: person.setBirthdate(new java.sql.Date((new Date()).getTime()));. After assigning all data i am calling person.save();.
I get a list of all persons from the database with this command: new Select().from(Person.class).execute();
If I do not close the app everything works fine (birthdate is always returned correctly from the database). However, when I close the app completely and then restart it, the birthdate is always null. All other fields (first name, last name etc.) are correct.
I really don't know why this is happening and would appreciate some help!
EDIT: After taking a closer look at my database I found out that the birthdate-column is not created. I am still not sure why the data is available when not closing the app though.
Second EDIT: I added a new column (a string) which is saved to the database and works just fine. So the problem is not an outdated database. All columns but the date column get created.
I also changed the date datatype to a string. The birthdate was then saved. Changing it back to a Date datatype resulted in the original problem again. Really weird... Does anyone know whats going on?
It should be some caching problem.
for saving Date try to use type serializer. it is so easy just read this page.
Related
I have been stuck on this problem for a few days and cannot find any help online. I want to take specific values from a .CSV depending on the user's location. My .CSV looks something like this:
State,Value
California,0.85
Arizona,0.95
New York,0.75
etc...
The app currently tracks the user's state and sets it to local like so:
final String local = address.get(0).getAdminArea();
I am trying to find a way to have the app look through the .CSV and find the row when local=[state] then take the value from the second column and set it to a double. I have no clue where to start and could really use any help anyone can provide! Thank you!
Just to clarify, I am not trying to print the .CSV, I only need to extract a single value.
Edit:
I solved the issue by using a buffered reader and reading the values into a HashMap then calling the correct key based on location.
I am trying to create an Exercise Tracker app in App Inventor 2 for a school project, and everything seemed to be going great until I made it to the third screen.
I hit my start button and it said Invalid Index 0, Size is 0.
This is my code: MY CODE.
Randy: Here is al link to an .aia file for my app. Using this, you should be able to view all my code. Let me know what you find!!!!
It will be in the comments-sorry!!!
First of all,your open another screen's screen no was invalid.
After i fixed it and tested it in the AppInventor's Emulator and it didn't show any error.
But I suspect that your problem was came from the data type of the global Time.The data type for the global Time is integer and the data that you store in the TinyDB is not only contents integer value (you can try to displays it in a label).So I would suggest you to store it in "Text/String" type rather than "Number/Integer".
Below is my way to store the Date and Time in the TinyDB after proper format it:
I need to work with a persistent String Array (n Rows, 1 column).
* On first running the app, the String Array needs to be created empty.
* On subsequent app executions the Array will be populated from a File and the contents need to be available throughout the rest of the app.
* As the app is executed, the Array needs to be able to 'grow' in row count
* As the app is executed, the Array rows need to be able to grow in length
* The user will have the option to Clear the Array of previous entries.
* At the end, the String Array contents will be written back to a File.
I find a lot of references to Putting and Getting from an existing SharedPreferences String[] but, in the newness of my Android development, I am struggling with how to proceed.
EDIT Follows...
The data itself suggests using an Array
Example:
MAIN ST. F55 63 KY08:57 12142015--------KY11:24 12142015345TMH KY13:57 12142015
MAIN ST. F56 WYE123 IN08:57 12142015--------KY11:24 12142015--------KY13:57 12142015
1ST ST. F57 --------KY08:57 12142015--------KY11:24 12142015789FPF KY13:57 12142015
1ST ST. F58 456FPF KY08:57 12142015998FPF KY11:24 12142015--------KY13:57 12142015
1ST ST. F59 789TTM KY08:57 12142015--------KY11:24 121420151234DG KY13:57 12142015
I first need to have this data in a File
Then in one GUI I check for the existence of the file.
If one exists, fine
If none exists, I create one.
Then, in subsequent GUI's, I must check for the existence of parameters
If they do not already exist, add them to the existing data lines.
If they already exist, notify the user
And so on and on.
Then when all of the current 'pass' data has been collected via multiple, separate GUI's, I have to write out the whole data-set into the file.
My reason for thinking that I need a SharedPreference approach is the need to find and check data from GUI to GUI as the user progresses through the app.
If that 'belief' is wrong, I am open to better approach suggestions.
EDIT 2 follows....
On further study of web references, I am beginning to think that perhaps the best approach for this data and how the data needs to change might be to use a SQLite approach. Any ideas about this?
Any assistance/suggestions you might have would be greatly appreciated.
i would discourage you from using sharedpreferences for anything else than preferences. means things that change rarely - really rarely and are really lightweight. do not put much data in there. less is better. the data structures underlying sharedpreferences are not a database.
another note. it is not a string list, but it would be a string set. sets are not necessarily ordered, nor do they necessarily keep their order. means - it is not rows. its a collection of strings that can come back in any fun order (usually there is some, but that depends on the implementation which i do not know)
now you could go and make your own list, your own data structure, save it into a string and read it out, use json to do exactly that or something similar, or better - use a database, which would exactly do that.
http://developer.android.com/training/basics/data-storage/databases.html
explains it, but as you'll see its something that might take some time.
now dont get me wrong, but i have to warn you about the following approach. it is valid, but has many problems and is far from thread safe. it will not be a problem as long as you only open it from the ui thread and do not keep anything in memory to cache - if you do it will create lots of problems.
your problem of adding a line and clearing can be solved by using a file. just a simple file
look here
http://developer.android.com/training/basics/data-storage/files.html#WriteInternalStorage
the change is to append when writing:
openFileOutput("filename", Context.MODE_APPEND);
see the context mode? now you can basically just write one line and append every time.
if you wanna clear the file, just deleteFile("filename")
this is as said not threadsafe, but can be a viable option if used carefully.
Please follow this step to achieve what you want with sharedPreference
create the class Parent for SharePreference
Create your empty Array
Convert Your empty array to String and put it on SharedPreference
to call your empty array from sharedPreference
Call your sharedPreference using your key
Convert the String to array
You get your array from the sharePreference
Hope it helps, and maybe this link will help you :
http://www.androidhive.info/2012/08/android-session-management-using-shared-preferences/
You can use my open-source library called prefser, which solves this problem and uses SharedPreferences and Gson under the hood. It's basically wrapper for default Android mechanism.
You can use it in the following way:
Prefser prefser = new Prefser(context); // create Prefser object
prefser.put("key", Arrays.asList("one", "two", "three")); // save array of Strings
String[] value = prefser.get("key", String[].class, new String[]{}); // read array of Strings
For more information check repository of the project, tests and README.md file.
Link: https://github.com/pwittchen/prefser
Please note, SharedPreferences have some limitations and shouldn't be used for storing large amount of data. If you expect a lot of data, consider using SQLite database or another type of database (e.g. with NoSQL or similar approach if you strive for simplicity).
OK, based on the data, how it needs to be manipulated and the pros and cons of using a SharedPreferences approach, I have decided to go with a SQLite approach.
With that approach I should be able to readily check:
* if the necessary table exists (if not create it)
* if the necessary Field1 + Field2 exists (if not create a new record)
* and I will be able to modify the record's Field3 contents as needed
Then when the user's actions are complete I can convert the SQLite table 'records' into strings and write them out as a File and then either DROP or PURGE the associated SQLite table (until needed next time).
I sincerely appreciate all of your suggestions.
Thank you.
Hey please pay attention to solve this problem I know this could be possible but I am not getting the way ..
I am using sqlite in android to store and manipulate the field as shown below in the figure
Figure http://s16.postimage.org/idc13pxdh/image.png
first_start_time,last_start_time,last_end_time are datetime field in SQLite database
I need to get the difference of last_start_time and last_end_time as mean of function so that I don't need to do it programatically
last_end_time = strftime('%Y-%m-%d %H:%M:%S','now','localtime')
last_start_time= strftime('%Y-%m-%d %H:%M:%S','2012-01-27 02:34:56')
,i,e if my firsttime is =2012-06-15 14:54:33
and Endtime is =2012-06-15 14:54:40
then time diff would be like this =00:00:14;
i want to have such difference time like last_end_time -last_start_time
i also want to use trigger to do use in sqlite data base in android
at the last I need that all my total_expended_time should get summed up like ...
select sum(total_expended_time) from study_result
.. one thing keep in mind the result should be in datetime stamp so that i can reflect it to my UI
Any suggestion will be appreciated
I have a question. In my app I have saved in my database some lists. Each list has asociated a date in this format 6-June-2011. How can I order these lists by date? I wrote I function like that :
public Cursor getAll(){
return (mDb.rawQuery("SELECT _id, Title, Shop , Data , Budget_allocated ," +
" Budget_spent FROM Lists ORDER BY Data",null));
}
but it doesn't work fine. I think it compare only the day. For example, if I have 31-May-2011 and 6-June-2011, it will say that the first date is after the second date.
It is possible what I am trying to do? Should I modify the date in format like this :6-06-2011?
Thanks..
I don't know anything about android development, but it sounds like your date field is stored as a string rather than a date, is that correct?
If so, you can either:
Change your table so that field is a date (then it should compare correctly)
Or store it in a standard format such that the default string comparison sorts dates correctly. Since string comparison sorts first on first character, second on second character, etc, this would be putting the biggest time difference first, ie. "2011-05-31" (include the zeroes).
(You should be able to convert the field by making a new field, copying the data from the old field into the new field in the correct format, and then deleting the old field and renaming the new one, or more simply if you simply want to change the format of the text. You should be able to do this either from code, or with an "update" query, AFAIK.)
Use a date format as follows...yyyy-MM-dd HH:mm:ss. This is guaranteed to be sortable in ascending or descending order.
If your Data column is not of type datetime there may be an issue. Take a look at this related SO question and answers:
SQL ORDER BY date problem