Similar custom expandable listviews in android application - android

I would like to have a few similar expandable listviews in my android application across a few activities. They all have the same content, but use different designs. Some have buttons for example, and some not.
I would even want to have three expandable listviews that share everything except the background color for each cell.
Anyways, having a unique adapter for each listview seems like a bad design practice as they all very similar. I was thinking of making an abstract adapter and than extending it for every listview, would that work? Is there any other approach?
Thank you.

Having a unique adapter for each listview seems like a bad design practice as they are all very similar.
That is correct. Duplicated code is almost always a sign of bad code design.
I was thinking of making an abstract adapter and then extending it for every listview, would that work?
Yes.
Is there any other approach?
Yes. E.g. if you want to have an adapter that supports different backgrounds, your adapter should take a background resource/color as constructor parameter. This approach fits for minor changes. If you want to have some non-expandable and some expandable listviews I would favor the inheritance approach.
The problem is that some of my listviews would be expandable, so I could not use Recycler View.
Recyclerviews are a better design choice than listviews. Creating expandable ones isn't too hard, see Expandable list with RecyclerView?.

Related

Whats the best way to put a customized scrollable list in android studios?

I'm trying to make a android app with a scrollable list like this one...
When I made this app in iOS, I used a UICollectionView. What`s the best way to make this in android studios?
I tried using a list view, but I can't seem to customize it to my needs?
Any Ideas?
ListView was a great way to start and it is customizable to your needs.
However I would recommend to use RecyclerView which works almost on the same principle as ListView but it is a newer concept in Android. It handles the usage of the ViewHolder pattern for you which makes everything super easy.(With ListView, you would've had to implement your own ViewHolder pattern)
All you need to do is to have the RecyclerView in your activity/fragment as the view to hold your data. Then, the key component is to implement the RecyclerView's Adapter which will handle the inflation and setup of each list item.
Here is a really great and short tutorial to get you started with RecyclerView.
If you're done with that here is a bit more advanced video material on RecyclerView from Dave Smith explaining a lot of ways on how to understand and use RecyclerView in your apps.
A ListView fed by an ArrayAdapter of custom objects can do the job.
You might have a class that contains the text and the image of a single item.
Then you can create an ArrayList with items of that class, where you put in all the data.
This ArrayList can be used as dataset for a custom ArrayAdapter, which overrides the getView()-method.
The getView()-method must inflate the xml-layout for each item and attach the data from the ArrayList to the inflated view.
You might want to implement the Viewholder-pattern to achieve a good performance and avoid unnecessary inflations and getViewByID()-calls.
You can also use the new CardView, which can make it a lot easier, since it is made for the new material design in android 5, which looks similar to your item list.

RecyclerView vs. ListView

From android developer (Creating Lists and Cards):
The RecyclerView widget is a more advanced and flexible version of
ListView.
Okay, it sounds cool, but when I saw this example picture, I got really confused about the difference between these two.
The picture above can be easily created by ListView using custom adapter.
So, in what situation should one use RecyclerView?
RecyclerView was created as a ListView improvement, so yes, you can create an attached list with ListView control, but using RecyclerView is easier as it:
Reuses cells while scrolling up/down - this is possible with implementing View Holder in the ListView adapter, but it was an optional thing, while in the RecycleView it's the default way of writing adapter.
Decouples list from its container - so you can put list items easily at run time in the different containers (linearLayout, gridLayout) with setting LayoutManager.
Example:
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
//or
mRecyclerView.setLayoutManager(new GridLayoutManager(this, 2));
Animates common list actions - Animations are decoupled and delegated to ItemAnimator.
There is more about RecyclerView, but I think these points are the main ones.
So, to conclude, RecyclerView is a more flexible control for handling "list data" that follows patterns of delegation of concerns and leaves for itself only one task - recycling items.
For list views to have good performance you'll need to implement the holder pattern, and that's easy to mess up especially when you want to populate the list with several different kinds of views.
The RecyclerView bakes this pattern in, making it more difficult to mess up. It's also more flexible, making it easier to handle different layouts, that aren't straight linear, like a grid.
ListView is the ancestor to RecyclerView. There were many things that ListView either didn't do, or didn't do well. If you were to gather the shortcomings of the ListView and solved the problem by abstracting the problems into different domains you'd end up with something like the recycler view. Here are the main problem points with ListViews:
Didn't enforce View Reuse for same item types (look at one of the adapters that are used in a ListView, if you study the getView method you will see that nothing prevents a programmer from creating a new view for every row even if one is passed in via the convertView variable)
Didn't prevent costly findViewById uses(Even if you were recycling views as noted above it was possible for devs to be calling findViewById to update the displayed contents of child views. The main purpose of the ViewHolder pattern in ListViews was to cache the findViewById calls. However this was only available if you knew about it as it wasn't part of the platform at all)
Only supported Vertical Scrolling with Row displayed Views (Recycler view doesn't care about where views are placed and how they are moved, it's abstracted into a LayoutManager. A Recycler can therefore support the traditional ListView as shown above, as well as things like the GridView, but it isn't limited to that, it can do more, but you have to do the programming foot work to make it happen).
Animations to added/removed was not a use case that was considered. It was completely up to you to figure out how go about this (compare the RecyclerView. Adapter classes notify* method offerings v. ListViews to get an idea).
In short RecyclerView is a more flexible take on the ListView, albeit more coding may need to be done on your part.
The RecyclerView is a new ViewGroup that is prepared to render any
adapter-based view in a similar way. It is supossed to be the
successor of ListView and GridView, and it can be found in the
latest support-v7 version. The RecyclerView has been developed
with extensibility in mind, so it is possible to create any kind of
layout you can think of, but not without a little pain-in-the-ass
dose.
Answer taken from Antonio leiva
compile 'com.android.support:recyclerview-v7:27.0.0'
RecyclerView is indeed a powerful view than ListView .
For more details you can visit This page.
Following are few key points/differences between RecyclerView & ListView. Take your call wisely.
If ListView works for you, there is no reason to migrate. If you are
writing a new UI, you might be better off with RecyclerView.
RecylerView has inbuilt ViewHolder, doesn't need to implement our own
like in listView. It support notify at particular index as well
Things like animating the addition or removal of items are already
implemented in the RecyclerView without you having to do anything
We can associate a layout manager with a RecyclerView, this can be
used for getting random views in recycleview while this was limitation
in ListView In a ListView, the only type of view available is the
vertical ListView. There is no official way to even implement a
horizontal ListView. Now using a RecyclerView, we can have a
i) LinearLayoutManager - which supports both vertical and horizontal
lists, ii) StaggeredLayoutManager - which supports Pinterest like
staggered lists, iii) GridLayoutManager - which supports displaying
grids as seen in Gallery apps.
And the best thing is that we can do all these dynamically as we want.
Major advantage :
ViewHolder is not available by default in ListView. We will be creating explicitly inside the getView().
RecyclerView has inbuilt Viewholder.
Advantages of RecyclerView over listview :
Contains ViewHolder by default.
Easy animations.
Supports horizontal , grid and staggered layouts
Advantages of listView over recyclerView :
Easy to add divider.
Can use inbuilt arrayAdapter for simple plain lists
Supports Header and footer .
Supports OnItemClickListner .
I think the main and biggest difference they have is that ListView looks for the position of the item while creating or putting it, on the other hand RecyclerView looks for the type of the item. if there is another item created with the same type RecyclerView does not create it again. It asks first adapter and then asks to recycledpool, if recycled pool says "yeah I've created a type similar to it", then RecyclerView doesn't try to create same type. ListView doesn't have a this kind of pooling mechanism.
RecyclerView info
The RecyclerView was introduced with Android 5.0 (Lollipop). it is included in the Support Library. Thus, it is compatible with Android API Level 7.
Similarly to the ListView, RecyclerView’s main idea is to provide listing functionality in a performance friendly manner. The ‘Recycler’ part of this view’s name is not there by coincidence. The RecyclerView can actually recycle the items with which it’s currently working. The recycling process is done thanks to a pattern called View Holder.
Pros & Cons of RecyclerView
Pros:
integrated animations for adding, updating and removing items
enforces the recycling of views by using the ViewHolder pattern
supports both grids and lists
supports vertical and horizontal scrolling
can be used together with DiffUtil
Cons:
adds complexity
no OnItemClickListener
ListView info
The ListView has been around since the very beginning of Android. It was available even in API Level 1 and it has the same purpose as the RecyclerView.
The usage of the ListView is actually really simple. In this aspect, it’s not like its successor. The learning curve is smoother than the one for the RecyclerView. Thus, it is easier to grasp. We don’t have to deal with things like the LayoutManager, ItemAnimator or DiffUtil.
Pros & Cons of ListView
Pros:
simple usage
default adapters
available OnItemClickListener
it’s the foundation of the ExpandableListView
Cons:
doesn’t embrace the usage of the ViewHolder pattern
In addition to above differences following are few more:
RV separates view creation and binding of data to view.
In LV, you need to check if convertView is null or not for creating view, before binding data to it.
So, in case of RV, view will be created only when it is needed but in case of LV, one can miss the check for convertview and will create view everytime.
Switching between Grid and List is more easy now with LayoutManager.
No need to notify and update all items, even if only single item is changed.
One had to implement view caching in case of LV.
It is provided in RV by default. (There is difference between view caching n recycling.)
Very easy item animations in case of RV.
In my opinion RecyclerView was made to address the problem with the recycle pattern used in listviews because it was making developer's life more difficult.
All the other you could handle more or less.
For instance I use the same adapter for ListView and GridView it doesn't matter in both views the getView, getItemCount, getTypeCount is used so it's the same.
RecyclerView isn't needed if ListView with ListAdapter or GridView with grid adapters is already working for you.
If you have implemented correctly the ViewHolder pattern in your listviews then you won't see any big improvement over RecycleView.
I worked a little with RecyclerView and still prefer ListView.
Sure, both of them use ViewHolders, so this is not an advantage.
A RecyclerView is more difficult in coding.
A RecyclerView doesn't contain a header and footer, so it's a minus.
A ListView doesn't require to make a ViewHolder. In cases where you want to have a list with sections or subheaders it would be a good idea to make independent items (without a ViewHolder), it's easier and doesn't require separate classes.
You can use an interface to provide a click listener. I use this
technique with ListViews, too.
No divider: Simply add in your row a View with a width of
match_parent and a height of 1dp and give it a background color.
Simply use a StateList selector for the row background.
addHeaderView can be avoided in ListViews, too: simply put the
Header outside the View.
So, if efficiency is your concern, then yes, it's a good idea to replace a ListView with a RecyclerView.
Simple answer: You should use RecyclerView in a situation where you want to show a lot of items, and the number of them is dynamic. ListView should only be used when the number of items is always the same and is limited to the screen size.
You find it harder because you are thinking just with the Android library in mind.
Today there exists a lot of options that help you build your own adapters, making it easy to build lists and grids of dynamic items that you can pick, reorder, use animation, dividers, add footers, headers, etc, etc.
Don't get scared and give a try to RecyclerView, you can starting to love it making a list of 100 items downloaded from the web (like facebook news) in a ListView and a RecyclerView, you will see the difference in the UX (user experience) when you try to scroll, probably the test app will stop before you can even do it.
I recommend you to check this two libraries for making easy adapters:
FastAdapter by mikepenz
FlexibleAdapter by davideas
There are many differences between ListView and RecyclerView, but you should be aware of the following in particular:
The ViewHolder pattern is entirely optional in ListView, but it’s baked into RecyclerView.
ListView only supports vertical scrolling, but RecyclerView isn’t limited to vertically scrolling lists.
I want just emphasize that RecyclerView is a part of the compatibility package. It means that instead of using the feature and code from OS, every application carries own RecyclerView implementation. Potentially, a feature similar to RecyclerView can be a part of a future OS and using it from there can be beneficial. For example Harmony OS will be out soon.The compatibility package license can be changed in the future and it can be an implication. Summery of disadvantages:
licensing
a bigger foot print especially as a part of many apps
losing in efficiency if some feature coming from OS can be there
But on a good note, an implementation of some functionality, as swiping items, is coming from RecyclerView.
All said above has to be taken in a consideration.

Android engineering: ListView versus just a dynamic LinearLayout

When you are working with a long, big list, certainly one should use ListView because it handles cell recycling.
Notice here, for example Can i use nested linearlayouts instead of list view, for a big list? the OP is asking about ListView verses a dynamic LinearList -- the answer is "have to use a ListView, because of recycling"
Now, say you are making a short list -- imagine say a popup with only 10 or 20 items. It may even fit all on the one screen, so there's no recycling.
In fact, is there any difference between using a ListView and just using a LinearLayout, and dynamically populating the little views inside it?
It seems to me that the latter is in many cases much simpler, more elegant, and easier to work with. But I could well be missing something that seasoned Android engineers know about.
Should I just use an ordinary LinearList (populate it dynamically) for lists where recycling is not relevant? What's the usual, and why? Cheers!
{Incidentally, for popup cases, is there some better, lightweight method for "choose one from a popup-list" that I'm too silly to know about?! :) )
ListView(and other lists) supports very useful idea: splitting data and view. These parts could be changed at any time so it's important to support flexibility. And it could be solved by special mediator object: Adapter. Adapter roughly speaking says how to fill your view with particular data item.
So I'm sure that if you decide to use LinearLayout sooner or later you will implement you own Adapter.
If you used dynamic linear view then rendering the view will take more time as compare to listview. In listview we are rendering views which are visible only but if you used dynamic linear view then its problem.

Efficiency of Listview with the flexibility of the ScrollView

I am trying to figure out the best approach for a particular UI for a particular data capture application, where I have a bunch of form widgets (EditText's and Spinner's) at the top of a vertical scrolling view, then a number of checked entries (10-200), and then a number of additional widgets at the end.
I am trying to think of the best way to get utilise the efficiency of the ListView (with the view recycling and option of the custom adapter for the checked entries), but the flexibility to include the other widgets before and after the list.
I have eliminated the idea of putting a ListView inside a Scrollview, for the well documented reasons.
I have also considered breaking it into multiple views and using the ViewFlipper, but this does not flow as well for the user experience.
The only other idea I have encountered is to put my non-listview items in as the Listview header and footer. This way I can still use my custom adapter for the listview checked entries, and the rest of the widgets are where I want.
Does this sound like the most efficient and sensible approach? Any comments and advice appreciated.
I have a custom listview with widgets above and below it in my app. ListView without ListActivity
Just put the listview in it's own LinearLayout and it should work perfectly.

Should I use a ListView?

In order to enter information into my database, I'm currently using a scrollview (with a table layout, iirc). However, looking at the api demos, I'm wondering if I should switch to a listview. It seems a bit of a strange way to do it, as I'd have to hard code the numbers of items, it would all have to be in java rather than xml, and each one would need a separate onclicklistener, but as far as layout is concerned it sounds like by far the easier to maintain.
(I'm considering the switch now as I'm doing a major rewrite anyway, so now would be a good time)
Anyone have any opinions that they wouldn't mind sharing? Would this be a horrific abuse of a listview, and should I stick with what I have? Or should I move to something that I can much more easily theme later on (my current layout is pretty ugly)?
I think of ListView as being the exact opposite.
You don't have to hard code list items: they come from various adapters like CursorAdapter and ArrayAdapter.
You can use a single OnItemClickListener to handle the click events for all of your items. onItemClick provides you with the position of the item that was clicked.
Even your presentation can be dynamic, since you can easily switch out a GridView for the ListView later.
I would recommend trying ListView; it will give you another tool to work with and inform your design decisions in the future.

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