I am a newbie here and hope you can help me out to clear some of my understanding (or misunderstanding). I have been reading for days and trying out based on Android guide to implement search function but it really didn't work out well. Perhaps I've got the whole concept wrong so do help me out here if you can be kind.
I have an app which data is from remote xml and I want to implement search function. I have 1 main activity (under my SRC -> my package)that list all the data retrieved from the xml. My questions:
1) In the guide, it saws we must define a .Searchable Activity. I supposed this is to handle the search query and store the result? If this is a case, do I need to create a new activity or I can use my main activity as .Searchable Activity?
2) After the above item is done, I supposed I need to create an activity to receive the result and do something. I take it as I need to create "public class SearchableActivity extends ListActivity" in the activity I define in item 1? The problem is that I don't know what to do with this as the guide are incomplete.
3) Presumingly I did it successfully and upon search, there are some results return, how do I show (or filter to show the search result) in my main activity? I do not want to have another UI to show the result as I prefer it just get filter to show the matched records
4) Lastly, since my data is from remote xml, do I need to "search" based on remote xml or it will search based on cache info on the app?
I am sorry for being so ignorant but I am totally new here and hope you can help me out. So far I have no problem, getting the dialog shown on my action bar. The only problem is that the search didn't work at all :( upon search, there is just nothing happened.
Thanks very much in advance. Cheers!
For searching in a list you can use built-in functions of android, but if you want a good result you can use your own function. The simplest function is:
for(int i = 0 ; i < arraylisy.size() ; i++)
{
if(arraylist.get(i) == youobject)
return true;
}
return false;
but there are better functions like binary search that you can use.
Now, how to create search activity?
First: create XML file an add a listview in it.
Second: create java file and link xml file to it.
Now use above code to search an object on your list. If in every search you find several items then add them to new listview.
Now create an adapter and send your search list to that.
Finally set your adapter to listview.
Related
I am new to Android App development, working on an android app which populate a list of numbers, in a listview dynamically, depending on the choice of the user, but, the moment user closes the App, the items in the listview are lost. How can I maintain the state of the listview?
Examples with code would be highly appreciated.
When I open Activity A, it allows users to add friends, and this friend list is shown in the form of items of listview in the same Activity, however, when I move to Activity B, and then come back to Activity A, this friend list disappears. I need to make sure that this friend list should not be lost while moving between activities. Please help.
I think that for your purpose there are 3 main methods, i'll explain them from the easier to the most difficult (in my opinion).
Text File
A way to do this is to create two methods in a class:
one has to create the text file in the storage if it isn't created before and read that, the other has to append a String to a StringBuilder and write it on the previous text file.
For this method you need the uses-permission of reading and writing to storage.
This link can help you: http://developer.android.com/training/basics/data-storage/files.html
JSON (also XML)
With JSON file you can create a list of objects with your data that you can serialize when you update the list and deserialize when you want to read it. For this purpose you have to study JavaScript syntax or, at least, JSON one.
SQLite Database
Android SDK incorporate a class named SQLiteOpenHelper that you can extend to create a database inside your app.
This link can help you: http://developer.android.com/training/basics/data-storage/databases.html
There are also references saving methods but i think that aren't right for your purpose, they work betters to save something like preferences or single data like last login informations.
I went through your comment. I would personally suggest using SQLiteOpenHelper
You might need to understand the use of SQLite, hence the tutorial
Simple Flow. On your Activity 1 where person Add Friends save it to DB
Then refresh the List from the DB. So when you move to Activity 2 and come back again to Activity 1 your List will refresh from DB. Hence no loss of data as you want.
EDIT
As user wanted to know how to use the ListView with DB.
Following are my suggestion
Sai Geetha
Youtube
I am working on my second Android Application, first being, hello world. The application code is quite crazy looking because I love to test new libraries and ideas in it. I have been working on this application for well over 3 months and one of my activities is getting way to large and difficult to work with. I find myself getting lost in the code and it is taking longer to do simple things. There might be simple solutions to solving this issue. I really want to split my activity into two and reference each other if possible. Is there are any suggestions to simplifying and organizing code that would be greatly helpful. Even example will help me very much.
Part of my activity is adding a ton of data into a database and the other part is a long equation with multiple values. Another part is implementing the HoloGraphLibrary (Which I love). It is also implementing a listView with custom adapter. It also has a custom dialog............ I can go on and on. I hope you get my point.
EDIT
Going to work with this.
HoloGraphHelper holoGraph = new HoloGraphHelper();
holoGraph.initialize();
Try creating classes for each responsibility.
A Database Helper that has functions to insert data too:
DatabaseHelper database = new DatabaseHelper();
database .insertData(whatever);
A HoloGraphHelper that initializes the HoloGraph
HoloGraphHelper holoGraph = new HoloGraphHelper();
holoGraph.initialize();
And so on.
Break into multiple files. First classes defined in the Activity like the adapter. Change anonymous classes to classes defined in their own file. Look for ways to break out other related code into a class.
Right click on src folder of your Project and select new - class to create a new class. You can use a class for storing methods but you won't be able to display anything on screen.
To display contents to user, you can create a new Activity bu pressing Ctrl + N and selecting Android - Android Activity.
The best way is modularise your code.
I.e split your code into various related modules, for example a separate class for each part that your testing. So you could have a database entry class, a class for Gui testing, i.e. for your custom dialog. That class does all the work for that test, into various functions, I always try to keep functions as small as possible as they are easy to read.
As an example for your database entry, you could have a function which checks the database if the record already exists and then insert it. But a better way would be your insert function only performs the insert code and instead within this function it calls CheckIfDatAlreadyExists function which can return a bool so you know whether you should go ahead and insert the record. This would keep the code tidy and clean to manage.
Then from your main activity all would need to do is instantiate the relative class and call the relevant method.
I'm new to Android development and i would like to make a single activity to show featured results using Youtube API and when a search query is typed, i want to update the same list with search results.
I got stuck in my first step, which is configuring the SearchView and receiving data from it. After adding a SeachView to the layout, i made a reference for it in the Activity java code, then internet documentation went too fuzzy for and i couldn't understand what should i do in my case (dynamic results).
you need to make listView's adapter extend from Filterable, and use its getFilter() function according to the query that is changing in the SearchView, using the function setOnQueryTextListener() .
it's that easy.
i also suggest that you watch the "the world of listView" lecture in case you want to learn some tips about using a listView. they also explain how the filter works.
I am working a project. I have lots of word text data and don't want to add layout and class for each one. I want to use sqlite, but don't know how. For example, there is a button, id is cat.
When clicking the cat button, a new screen opens and shows information of cat. One layout, one class, but lots of screens. The data must come from sql because there are too many animals.
Thanks in advance.
You have given the answer already yourself: SQL database may be your friend. Work yourself through this tutorial and see how far that brings you. You'll have to manipulate the UI from code, that is doable as well.
Another approach you might want to consider is putting everything in XML into strings.xml file(s). This depends a bit on the size and structure of your data. From code you can reach this using getString( R.id.blah ).
Call other screen passing values.
In the button click do:
startActivity(new Intent(this, SecondScreen.class).putExtra('Identify', 'Value'));
In the Second Screen do:
String value = getIntent().getStringExtra('Identify');
Now, take that value and make the query in SqLite and display the result.
Hi I need a little help with an issue that I have.
I had to build an application which needs to show only a text information and pictures.The content was a lot, that's why instead of creating 200 single activities for very page I create one base activity which content I'm changing everytime depends on which listview item is clicked using putExtra(); and getExtra();. So the problem now is that they want me to create Favourites page, where the users can save some of the information and access them on a single activity.Actually it's really easy to do this using sqlite,but they want from me to finish the application today, within a few hours.My problem is that If i start coding it again and insert all that information in database it will take much more time for me.
So here is a little more explanation :
1.I have base activity with a listview.
2.When user click on listview item I send the content using putExtra in base activity.
So I need to learn how to save the id of listview item or something else and show that content in new Activity. I was thinking of using SharedPreferences but not really sure how to deal with that.
Any suggestions how I can do that...for a few hours.
Thanks in advance!
What kind of content is it? Is it over 200 entries and you don't save them locally?
Just knowing if it's a favorite or not can not be more than one hour job using sqlite. Just keep the id of the content and then a value to see if it's a favorite or not.
Noone will really do that for you since it's obviously your (paid?) job. The fact that you can't do it in time is really not a reason to skip the best option to use.
I would say don't be that optimistic about what you can achieve in which time. Manage your resources better and you will not have that problem.
You can achieve this with sharedpreferences too,but it's not a good idea.
The best way is to do it with database,but it's up to you.