I am using a ListView in combination with a HashList to show data from an SQL Database through JSON. Everything works fine. But now I want to have a special feature.
In the ListView are round about 400 Items. So if i click one of the item to view its content and switch via Backbutton back to the Listview, i want to have the viewed Item from the Listview being marked in another color so that the user sees directly which oh the items he already has clicked.
I painted an little grafik for you, for better understanding
On the left side, the original View. After i View the 1st,5th and 8th Item of the list, the list should look like at the right side.
Is this possible?
You can implement your own adapter, then have an boolean array to store the current status of every row, and in the getView function assign a different color to the background of the selected rows based on your boolean array.
For this you will need also to set an onClick event in your rows to open the previsualization view and there also check the boolean array as "visited".
For more info about how to make custom efficient adapters, please read this
To simply let the user choice more than one row you can use
listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
in your list
Related
I'm stuck on a little problem.
When I click on a row in my RecyclerView, I'd like to change its color to some other color (i.e.: red).
Then, if I click this row again, I would like to set its color back to the normal one (i.e.: white).
Then, if I click on a second row or n-th row, I would like to do the same.
I've tried to work on the RecyclerView Adapter class, in my ViewHolder I tried some ideas counting user clicks, setting a boolean to check the colored rows, and getAdapterPosition to know what is the row's position... but actually all my tries failed!
Would you please help me with that problem?
It seems that I'm close to the solution, but need a little help
You're going to need to keep track of which items were selected on the list (otherwise any changes to the view will simply be recycled).
Keep a list of selected items within your adapter. In the adapter's onBindViewHolder you can check against the list and if the list contains the view/item, you can color the view accordingly.
Edit: Refer here for a working example
How to properly highlight selected item on RecyclerView?
I'm building an android app and I'm trying to replace a list view with another list view if you click a button, like the notifications page on Instagram. On that page, if you click on the top "following" button it will show you a listview of what your followers have liked. If you click on the "you" button it will show you a listview of what people have liked your photos.
Any help would be greatly appreciated!
You can do it by following ways,
1. add Two listviews and can change the visibility as per your requirement.
2. On button click you can load the other data into same list view and can update your adapter in the same list view.
in 1 you have to load two list view at first which will consume more time if data is larger sure you can write a login in asynctask to load list views in background thread.
in 2 you have to update your adapter at the button so you will have to provide some progress bar of dialog for user while you list view is getting update.
You can use either of this whichever suites you best.
Simply , You don't need to switch Listview , you only need to switch adapters .
eg, you can switch to mFollowingAdapter when clicked on Following button and switch to mYouAdapter when you select "You" tab. that's it.
You should write a list, that has a custom adapter. This adapter will be able to display BOTH views you want to display.
If the data to be displayed is the same format (ie. both have an imageview next to a textview), you are in good shape.
When you want to switch to a different list, get the information you would like to display, replace the data in your the collection backing your list, then notify the list that the data has changed, and it should redraw.
So, this might look like:
create ArrayList() with data A
setup List, with this data and display
replace the ArrayList() with data B
call listView.notifyDataSetChanged
You can still do this if the Data A, and Data B have different views, in this case, you would need to handle this logic in your custom adapter.
I am trying to better understand the internal functioning of ListView as it pertains to selecting one or multiple items- it's actually amazing how difficult it was for me to even get this far in my understanding.
By default a regular click on a ListView item is setting the 'checked' state for that item to true. How do I override this behavior so this selection does not happen?
And more fundamentally, what are the underlying ListView mechanics here? Is the row view's default onClick then calling the ListView's onItemClick/LongClick handlers, or how does this click handling get sequenced?
I do want to allow a choiceMode of multipleChoice, but I only want to select it onItemLongClick. Overriding onItemClick does not change this behavior, and overriding the row view's onClick handler in the adapter getView() function seems to prevent the ListView onItemClick and onItemLongClick from ever happening.
Below is more detailed context on my application
My goal is to have my ListActivity display a ListView, which functions as follows:
Clicking an item performs a non-selecting action (expands the row to show more info)
Long clicking an item selects it. Selecting an item is indicated by highlighting the background of the row (as in the Gmail app)
You can select multiple items
My application structure is:
Activity is an extension of ListActivity
Adapter is an extension of ArrayAdapter<>
ListView row layouts are completely custom layouts (not any sort of built-in ListView row layout)
My understanding of the built-in functionality for ListView has me to the point where I am
setting choiceMode to multipleChoice
using the ListView 'checked' functionality for making and tracking the selections
using a custom selector as an 'activatedBackgroundIndicator' to show the highlighting (example here)
Keep an ArrayList to maintain ListView items selected position. When a ListView item is selected check in that ArrayList whether item position is in ArrayList or not. If item is not in ArrayList change state of Item to checked else change state to unchecked and remove the position object from ArrayList. This worked for me.
I want my ListView to work something like the following:
When I press a button (probably from context-menu), I want the user to be able to select more then one item from ListView (probably using check-boxes), but those check-boxes should not be visible before that.
So, the point is, after the user presses a button (let's say "Delete more items"), the listview, should update itself, and appear on every row of the list, a checkbox should appear (allowing me to select the items ID to pass those to server).
How can I achieve that, without having to recreate the list from zero? (how to setVisibility ON, keeping the other content of the ListView as it is, and not doing another request to server).
PS. If you guys, have another better idea, on achieving the Delete More Items, would be much appreciated!
This is just an idea, haven't tried it myself: you build in a checkbox in your listitem layout. Normally, in the getView of your adapter, you set it invisible with
checkBox.setVisibility(8);
When you want to show them, you set some boolean
showBoxes
of your adapter to true, then in the getView oyu don't hide the checkboxes.
Then
notifyDataSetChanged
on the adapter.
Hope it's clear what I mean.
I have created a custom ListView.. every element of my ListView constructing from a layout.
My layout will have some TextViews and a ToggleButton. My ListView will have some 50 elemnts and my device screen can show 2 elements at a time.
Now if we select ToggleButton on a Item and scroll down my ListView , the selected item will be out of screen and when I come back to the previous selected item I am observinf that selection for that toggle button is gone.
I know that this is a normal behavior in android that It will construct the elements which is currently displaying.
But I want to keep that value.. Is there any way that we preserve selection. or can I tell ListView to donot construct every time.. memory is a not a issue for my application.
Please let me know if there's any good solution for this.
You could store the states of the checkbox in a map with the position as the key. So whenever the list reloads after scroll, it loads based on the hashmap state. You should write this logic in the getView()