This week’s homework in the android class was to create a simple ListView using ArrayAdapter instead of generic ListAdapter.
ArrayAdapter
ArrayAdapter is a special kind of ListAdapter which supplies data to ListView. You can refer to my notes for last week to know about ListView and ListAdapter. You can also read about ArrayAdapter in android documentation.
Adding views
First create an empty android project. Then edit the main.xml layout file to add a ListView. Then create another layout xml file which will contain the TextView (or any component) that will be displayed within the ListView.
Editing Activity
The next step is to change the generated activity class to extend from ListActivity. This is very important because only a ListActivity will be able to display the ListView.
Binding the adapter
The next step is to bind the ArrayAdapter to the ListActivity. We can do this by calling the setListAdapter() method.
To this method we have to pass an object of type ArrayAdapter. You can pass an object reference to this method or we can even create a new anonymous method like below.
We have to override the getView() method of the ArrayAdapter class to create the TextView (or any other component) which will be created for each list.
Finishing up
So that’s it, you are done. 🙂 All you have to do now is to save the project and run it in the emulator. If everything is done properly, then you can see the list of items displayed in the ListView like below.
Source code
I have uploaded the entire project source code into github and you download it from there and verify it with your code.
Try to complete the homework, before the next session and do come back to view the notes and the homework for the next session too. 🙂
You can also subscribe to my blog’s RSS feed or follow me in Twitter to receive updates about my notes for the next sessions.
thank you very much… this is the first example of an listView which is working and easy 2 understand!
Nice to know that it was helpful to you.
It will also help you alot
http://mfarhan133.wordpress.com/2010/10/14/list-view-tutorial-for-android/
Sudarmuthu,
As tomig stated, I have to reiterate, “this is the first example of an listView which is working and easy 2 understand!”
All of the other tutorials were a rehash of Google’s which are valuable, but they are built upon a mountain of “simplified” “helper” classes. I wanted to get back to basics as I will be binding some arbitrary data to some simple lists, therefore, I cannot rely upon the SimpleList2Adapter (or whatever).
I do want to point out a problem I had when I created my layout with the ListView. I like to provide my own @+id and this caused the error below until I looked at your solution and found:
android:id=”@android:id/list”
Without this attribute set, I did not understand the error, nor did I know how to fix it:
08-13 17:49:58.148 E/AndroidRuntime(19308): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobibob.android.myapp/com.mobibob.android.myapp.HomeActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is ‘android.R.id.list’
-Regards,
mobibob
Mobibob,
Nice to know that my article was helpful to you 🙂
android:id=”@android:id/list” is a predefined id which is created by the platform. You can either use it or create your own id.
greate job,dude,thank you so much
hi,
can you give an example where i can update the listview dynamically..
say for example i have a search app, i need to show the results as they are found…
This tutorial is crap; you speak of using a ListView, but you’re not…you’re using a ListActivity, which means your activity can have only one single list view and zero additional functionality.
You are always welcome not to use the stuff from here, if you find it to be crap 🙂
Hey!
Could you please explain “row = mInflater.inflate(R.layout.list_item, null);” I am a total noob at android and I don’t know what a inflater is. Thanks!
It basically converts your layout from XML into views. It is a built-in function in Android.
Thank you, thank you, thank you!!!
You have no idea how many hours I’ve spent on this. Ironically, this is part of a homework number 2 I am working on as well. The key “thing” you said in your write-up was that you needed a SEPARATE layout .xml for the TextView item that populates the ListView. That was the key… NOWHERE on developer.android does it make that clear.
again, thanks!
Nice to know that it was useful to you. Comments like this really motivate me to write more posts 🙂
“This is very important because only a ListActivity will be able to display the ListView. ” This is incorrect. A ListView can be shown by any activity
check this androidguide tutorial http://sanathnandasiri.blogspot.com/2011/11/how-to-work-with-android-listview.html
Hi,
Thank you for your post. I found it very helpful. I’ve been trying to find some good examples or something that explains well ListAdapter, however, all the examples on the web are pretty useless. Then I came across your posting and it was well explained. Thank you!!
Can you help me to clearly understand this… You mentioned that it should be extended from a ListView, and you mentioned the generated Activity. Which one exactly are you talking about ? the mainActivity.Java or the separate class ?
I am talking about the main Activity class in your app, that you have mentioned in the manifest file.
hi,
can you give an example where i can update the listview dynamically..
say for example i have a search app, i need to show the results as they are found…
I am working on a project that requires me to retrieve info from GAE Datastore and display it on the android app in a list view… can you help me on this pls ?? how do i go about this task.. ?
Hey,
I need to add data to list view from two EditTexts using Add Button.I can add data ,but I can’t increment the row count.So,if I add new one even it is display on previous row without adding new row.Please tell me how can I increase a row…
Thank you
how do i add images to list view??
Hello,
I am looking for small story app, I have some images and audio file using that i want create an app for kids, where kids can do horizontal swipe and behind that image the audio file will run describing what image is all about.
Do you have any sample source code which does the similar stuff on Android, or link to similar open source code will help me to go ahead.
Thanks,
I need explanation & use of ARRAYADAPTER
Iam getting this error what to do???
“The method setListAdapter(new ArrayAdapter(){}) is undefined for the type Main”
very nice and informative
thank you it helped to solve my problem
Iam getting this error what to do???
“The method setListAdapter(new ArrayAdapter(){}) is undefined for the type Main”
replyy me please…