Is there a way to determine if a list view needs to scroll to display all of its contents?
In other words, are the combined heights of all the children greater than the height of the list view itself.
I have not tried using it this way, but in principle if getLastVisiblePosition() equals getCount()-1, all items should be visible. It's possible that there is still a bit of scrolling needed, less than the height of a row, and I don't know if that matters in your case or not.
If it does, you could always iterate over the visible children and sum their heights.
I tried some ways a while ago and ended with simply calculating and comparing the height of the list view with the sum of the heights of all items and the sum of all separators.
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I'm trying to align some items inside a RecyclerView with others outside it. However, seems like all my tries are failing.
What I'm trying to do specifically: I have a couple of views as a header which are aligned using various methods* then a RecyclerView just below it, in its same parent, stretching the whole width, that inflates views.
The problem: Items inside the RecyclerView do not align perfectly to the items outside of it. Knowing that I'm using the same layout for both the parent and the items! And knowing that whatever method I used for horizontal alignment for the header items, is exactly used the same way for each item inflated for the RecyclerView. AND knowing that both items have same properties (they're TextViews, same size, width, height, etc...)
What methods have I tried? FOR BOTH SIDES (up and down), I tried the following:
Using ConstraintLayout for both parent and item layouts, and stretching the items between both start and end of parent, then using the constraint ratio to position it exactly where I want. Outcome for header is different from that of RecyclerView holders.
Using a TableLayout with children stretched across the whole width, same number of columns, same stretching, still different outcome, not pixel perfect.
Placing the header views exactly how I want, but not using any Android placement 'methodology' at all, but instead getX() and setX() later inside the adapter (using .post() so I ensure the position is accurate after inflation) and STILL the same wrong placement.
What am I missing? Shouldn't a RecyclerView inflating children that span the whole width when I specify they should match_parent? I tried debugging the X values for header and view holders, THEY'RE THE SAME but my eyes see different things. I delayed it for some milliseconds but this didn't change a thing.
So the problem turned out that whatever method I used, if the TextViews widths were wrap_content it'll always fit the word inside it. The solution was setting the width to 0dp and let the parent ViewGroup balance everything evenly. In my case I used a TableLayout.
I am trying to move my app from using GridView to using RecyclerView with GridLayoutManager. I am new to RecylcerViews, but have successfully converted my ListViews, now working on my GridView. A couple things I am unsure about:
My current GridView has a certain number of columns, determined at runtime, with each grid column the same, hard-coded width. It is scrollable both horizontally and vertically (I wrap my Gridview in a HorizontalScrollView). So I basically need to have a view with a set number of columns that are a set width, irrespective of screen width.
I have been having problems finding a method to set the column(span) width for GridLayoutManager, so I assume that is not how GridLayoutManager. It almost sounds like it is built to always fit all columns on the screen, rather than letting them spill off the screen? What is the best way to tell GridLayoutManager that I want, for example, 6 columns that are each 150 units wide (either dp or pixels)?
For scrolling in both directions, it sounds like I can use my current approach and just wrap my RecyclerView in a HorizontalScrollView, is that correct?
Make the width of the RecyclerView wrap_content and set the number of spans you want. (Make sure parents of the RecyclerView are also wrap_content.) When you create the item views in the RecyclerView's onCreateViewHolder() make sure that it is the width that you want. The RecyclerView will grow to the width of the view holder layout times the number of spans.
All you need to do now is to wrap everything in a HorizontalScrollView.
So i'm trying to hack away an issue I'm having. To reach my goal of not having views i set the height of the view, in the adapter, to 5 pixel. To make sure they're being drawn i also set the background color to a whole different one.
When calling getChildCount in the custom listView It doesn't seem to count the smaller views even though they are clearly visible and on the screen.
I'm wondering if the listview is miscalculating the number of views in the screen due to the difference in height and if so how should i fix it.
I have a list view which is rendered each time with a different list of items, with variable height.
What I want is to set all the Views in the list view to the same layout height according to the view with the highest layout_height, when setting it to layout_height="wrap_content" for each View.
Also I would like to apply min and max values for the height.
So if I define min=30dp,max=100dp, and the biggest View is automatically rendered with 70dp
all Views in the ListView should be set to 70dp.
I have no idea how to go about it, expect for calculating in the code the max view height values, and setting them to all views, but this doesn't seem very elegant to me, especially as I need to translate it to DPs in the code.
Any simpler ideas?
Your right what you try to achieve wont be as pretty as the regular way, but it'll work ;) usually you would decide height beforehand and then go with it :)
I need to calculate the measured height of my views without measuring all views, because these views contain images fetched from the internet. When I measure the views, they download images to memory and I an catch out of memory exception. I use custom ScrollViews, which work like ListViews, display some part of views and when scroll, add to bottom or top.
How can I calculate the height of all my views without throwing out of memory exceptions?
Or how can I make ListView calculate its height before rendering views?
You can use getLeft(), getTop(), getRight() and getBottom() these method's on view. for more information . see following link
http://developer.android.com/reference/android/view/View.html
You answered your own question:
display some part of views and when scroll, add to bottom or top.
ListView does NOT know the heights of items it has not yet seen. It lays out some or all of the items it knows, adds an extra bit of UI at top and bottom to visually indicate that there may be more items, and scrolls that. The total scrollable range for ListView can change as it adds more items.