Currently I have implemented Expandable List View referencing from the following website:
http://www.androidhive.info/2013/07/android-expandable-list-view-tutorial/
Now, how do I download a jpeg from a url(e.e. h--p://www.test.com/image.jpg) and display this image within each list child when that list child is chosen? Currently it only shows data.
The reason is being, I don't want to download the images and store within the assets folder which will increase the size of the application, that's why use url to show only when that list child is chosen.
Is it possible? Or I could only do so by downloading the image beforehand and storing under assets?
Yes it is possible. If you want to implement this then you should grab a lazy loading library. For that you may use aquery just google it, its a nice library to provide the required mechanism.
Also Expandable istview is nothing but a listview so whatever you want to do inside a listviewcan be done within ExpandableListView as well.
Related
I'm developing my first app and have been reading a LOT here.
I've been trying to find a solution for the following issue for over a week with no luck.
I have an Adapter that extends ArrayAdapter to show image and 3 lines of text in each row.
Inside the getView I assign relevant information for the TextViews and use ImageLoader class to download image and assign it to the ImageView.
Everything works great! I have 4.5 rows visible on my screen (out of total of 20). When I scroll down for the first time the images continue to download and be assigned in right order to the list.
BUT when I scroll back the list looses all the images and start redrawing them again (0.5-1 sec per image) in correct order. From what I've been reading it's the standard list performance but I want to change it.
I want that, once the image was downloaded, it will be "sticked" to the list for the whole session of the current window. Just like in Contacts list or in the Market. It is only 20 images (6-9kb each).
Hope I managed to explain myself.
you need to cache each image after download it, and each time the adapter need it check if its already downloaded get it from cache (disk or memory) otherwise download it.
at first i recommended you to read this tutorial from android dev site http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html
or use an external lib like this one https://github.com/koush/UrlImageViewHelper
The problem here is that the ArrayAdapter is reusing the list view rows as you scroll, so as you scroll down, the top row will be reused and inserted at the bottom of the list (for performance reasons).
Your best bet here is to try to cache the images locally on your device to avoid calling the ImageLoader every time.
One pretty good library that solves this problem is ignition. It's open source and available here: https://github.com/kaeppler/ignition
Take a look at RemoteImageView for a good example of the caching mechanism.
I'm developing an Android App and I need to display some data in a scrollable Listview.
I will extract some strings from objects that I right now have stored in linked lists (until i come up with a better solution).
I want to display a view that looks almost like the contacts app. A list with a small picture to the left and a larger text to the right of the picture with a smaller text the bigger one. When I click on one of the items it should open a new activity.
How do I create the view? If I adds an object in the linked list it should appear in the list.
I have checked some sample code, but they all uses Arrayadapter and I dont understand how I am supposed to do.
Check this article about Adapters: http://www.vogella.com/articles/AndroidListView/article.html
If you want to add new objects in ListVew use:
adapter.notifyDataSetChenged();
Check the libraries in this question, you have what you need there:
Lazy load of images in ListView
What is the best practice for loading images from the Web into a ListView?
Do I have to load them first into SQLite database or should I load them directly into a ListView?
And also after clicking an item in the ListView I have to show the same image in another activity. Is it the right way to pass this image to another activity or it is better to load it from Web / SQLite once again?
Look here Lazy loading of images
Loading them directly into the listview will make scrolling in it slow, as it will reload them everytime they get visible.
do that Google recommended http://developer.android.com/training/displaying-bitmaps/index.html
hi i am going to make a to-do list so what i need is that to assign my task and view it as a list view in those list view need 3 text view and 3 images in this 3 images represent 3 activity like alarm, calendar and so on when i click these images its open seperatly i had i know to retrieve the data's from database to list view but did not know how to set multiple image in a single list.and make those images click able.now how can i do that i tried the lazy adaptor but it is used in the parsing phases there is no parsing in my application please help me
there are many different post all over the place about creating custom ListView items. this one is very helpfull and similar to what you want to do.
when working with images and ListViews, it's very important to implement Lazy image loading. the best implementation I know, is ferdovlasove's LazyAdapter.
enjoy...
Hi can anybody tell how to add webview in list view in android
Thanks
What exactly do you want to archive by doing that? You can use something like list_item.xml to create a layout for a single item of ListView. But the content of your items is provided by an adapter, which provides data fast. To load web content may take time, consider that your list should enable fluent scrolling.