For an Android App, I'm using a GridView and extending BaseAdapter to organize its contents. For the function getView that I override in my extended BaseAdapter class, I create a LinearLayout, which I attach an ImageView and 3 TextViews to. Now, I need to implement convertView, but because I created my views programmatically, I didn't think I can use findViewById to find these child views to change their properties (like text and bitmaps).
I had the idea of assigning a unique ID pertaining to different types of views for each one when I create them (example: give my name textview the id of 1, description textview the id of 2, etc), but I was not sure if the ids have to be unique among every view, whether they're the same kind of view or not.
Ultimately, how do I find a child view that's part of a linearlayout view which were all created programmatically?
You can get children of LinearLayout via getChildAt() but it's hard to distinguish what child exactly you get.
I think assigning IDs is better way. You can assign IDs to your views and later get views via findViewById(). IDs doesn't need to be unique for each LinearLayout.
Something like this:
// Give more sensible names to ID's
int IMAGEVIEW_ID = 0;
int TEXTVIEW1_ID = 1;
int TEXTVIEW2_ID = 2;
int TEXTVIEW3_ID = 3;
imageView.setId(IMAGEVIEW_ID);
textView1.setId(TEXTVIEW1_ID);
textView2.setId(TEXTVIEW2_ID);
textView3.setId(TEXTVIEW3_ID);
...
// somewhere later
ImageView imageView = (ImageView) convertView.findViewById(IMAGEVIEW_ID);
Related
I am adding multiple XML Views programmatically. I'm using a layout inflater to add them and there are no problems with that.
But I'm not able to modify the TextView in each of them.
For example, consider I am adding a LinearLayout three times in my final View. I have a TextView in that linear layout. I extract it using findViewById and if I setText("hello"); it is being reflected in the first layout, but not the second and third.
Will the inflater create new ids dynamically when adding multiple XML elements?
To answer part of your question, no: Ids are not dynamically generated by LayoutInflater.
When you say you are adding the views, where are you adding them? You mention a final View.
You don't include your code, but I assume you are calling Activity.findViewById. If you call this.findViewById from your Activity, you are traversing the entire View hierarchy and finding the first view with such an Id.
What you need to do, is iterate through all of the LinearLayouts that contain your TextViews and call findViewById on each of them.
for (LinearLayout layout : <fill in>) {
((TextView) layout.findViewById(R.id.yourid)).setText("hello");
}
As for the <fill in>. Hard to tell how to fill it in without your code. It seems like you are adding these into a parent view right? Let's assume we have a parent View parent = some view;.
You just have to get all of its children and iterate. There are a few ways you can do it depending on which subclass of View the parent is. Let's keep it simple and assuming the parent is just another LinearLayout.
In that case the for loop changes to something like:
for (int i = 0; i < parent.getChildCount(); i++) {
final LinearLayout layout = (LinearLayout) parent.getChildAt(i);
((TextView) layout.findViewById(R.id.yourid)).setText("hello");
}
Short Story:
I have a layout "layout.xml", which gets replaced by another layout "success.xml" after a successful web request. Both layouts have an ImageView that provides the backgrounds to the layouts. These 2 backgrounds both need to be the same, and both are dependent on a user preference.
Longer Story: This all happens in a Fragmnet with an AsyncTask replacing the contentView with "success.xml" in onPostExecute after the web request. This happens as follows:
View view = getView();
view = null;
view = View.inflate(context, R.layout.success, null);
What I tried to do is give both ImageViews the following android:id="#+id/background_image" and then call
ImageView background = (ImageView)view.findViewById(R.id.background_image);
background.setImageResource(R.drawable.bg1);
This background-setting works for the initial view (layout.xml), but on trying to change to "success.xml", I get a NullPointException because background is null.
I've checked and the View's id is set to -1 while the original view's background_image id is set to something sensible and valid.
I've also tried setting the second view's background id like this: android:id="#id/background_image", i.e. without the '+', but still no luck.
The added complication is that it's not just 2 layouts, but about 5 that I need to do this for, so it would be really handy to recycle view id's.
Any help would be greatly appreciated.
Your code for replacing the fragment's view will not do what you want, the original view will remain the same as you change only a reference to that view and not the actual object.
To replace the view of the fragment with the new layout you could have another ViewGroup(for example a FrameLayout) in the basic layout (layout.xml) wrapping your current content(don't forget to give it an id) of layouts.xml(as I understand this is the basic layout). Then, when it's time to replace the layout you could simply do:
// remove the current content
((ViewGroup) getView().findViewById(R.id.yourWrapperLayout)).removeAllViews();
// add the new content
View.inflate(context, R.layout.success, ((ViewGroup) getView().findViewById(R.id.yourWrapperLayout)));
You could avoid adding an extra layout if, by any chance, all your five layouts have the same type for the root view(like a LinearLayout etc). In this case you would use the same code as above but you'll modify the other layouts file to use a merge tag. Also, you'll be looking for the id of the root in the layout.xml layout into which you'll add the content of the other files.
Then you could have the same ids, but you'll have to reinitialize any reference to the views(meaning that you'll have to search for the view again if you store a reference to the view(like a Button field in the fragment class)).
Is there a way to create an array containing actual instances of views. For example, if I have one LinearLayout called Container that has within it 3 other LinearLayouts with the same Tag attribute and I wanted to get a list containing all 3 LinearLayouts so I can loop through and handle each.
Tried:
LinearLayout[] layouts = (LinearLayout[]) Container.FindViewWithTag(tag);
and
List<LinearLayout> layouts = (List<LinearLayout>) Container.FindViewWithTag(tag);
and
foreach(LinearLayout layouts in Container.FindViewWithTag(tag))
None of these have been acceptable to Android so far. Another acceptable way to handle my situation would be to just be able to assign each LinearLayout a Parent. But I haven't found a way to programatically set a view's parent, only how to get a view's parent.
What I have understood from your question that you want the child of Linear Layout. Yes, you can get the child of linear layout by container.getChild(index)
for(int i=0;i<container.getChildCount();i++){
View child=container.getChildAt(i);
//your processing....
}
I have an android app which asks a question followed by x number of options.
Each option contains a textview, ImageView and a radio button.
The value of x (i.e. the number of options) is not constant. I want to dynamically add UI content to satisfy this requirement.
At the moment I have written the code in the layout's xml to display a maximum of 4 options. If number of options is 2 I hide the options 3 and 4 using something like
tvoption1.setVisibility(View.GONE);
tvoption2.setVisibility(View.GONE);
However this is not very scalable. Can anyone tell me how to add options for java dynamically. Or is there a better approach?
A View can be added at runtime by using the inflater like this:
LinearLayout linearLayout = (LinearLayout)inflater.inflate(R.layout.news_categories_item, null);
TextView categoryValueTextView = (TextView)linearLayout.findViewById(R.id.news_category_item_value);
mMainLinearLayout.addView(categoryValueTextView);
In this example, a LinearLayout containing a TextView is inflated. A reference to the constituent TextView is then obtained, and the TextView is dynamically added (at runtime) to the main linear layout (mMainLinearLayout).
The inflater object may be obtained in an Activity by using getLayoutInflater().
create your row layout separately, from the main xml
Get LayoutInflater service from context:
LayoutInflater inflater=(LayoutInflater)getSystemService(LAYOUT_INFLATE_SERVICE);
use following method to addview to main xml, I assume you have parent layout llParent in xml and you want to add items in this llPaent, from list list.
for(int i=0;i<list.size();i++)
{
LinearLayout llView=(LinearLayout)inflater.inflate(R.layout.row);
//get view id and set values
TextView txt=(TextView)llView.findViewById(R.id.text);
}
A ListView is a good view for displaying several similar items. Here is a tutorial (Other views with adapters are good too, such as GridView or Gallery).
You will probably want to create your own adapter for the list, so you can display all three views (checkbox, image and text) as one item, but there are lots of examples on that available on the net as well as here on SO.
I am trying to create a simple game. I would like to populate a LinearLayout which I have defined in an XML with several RelativeLayouts. Each time the user presses a button I would like a child View to be added to the LinearLayout. Each RelativeLayout would change slightly based on the users input (which buttons were pressed, etc).
I essentially want to create a new RelativeLayout based on an XML layout file. I then want to manipulate some attributes of the RelativeLayout's child Views (specifically the src of some ImageViews) and add it to a LinearLayout. This in itself is not particularly difficult. I can get at each of the RelativeLayout's children using findViewById but I start having problems when I want to create n number of RelativeLayouts based on the same XML. I'm pretty sure duplicate IDs are causing crashes. Can a RelativeLayout work without using IDs? Should I try and find a different way of constructing the interface using different ViewGroups?
I'm not sure if what I am asking is even possible but I know that creating these items on-the-fly using the code alternative to the XML layouts is a horrible thought.
Thank you in advance.
EDIT: I lost my train of thought halfway through, the previous example had some bugginess. I've updated.
pedr0 has the right idea, but to clarify, you could try something to this effect (assuming you have a RelativeLayout defined in relative.xml). This isn't tested, but the general idea should be valid. You don't even have to do a separate method, you can do it inline in a click handler, or whatever, but I just did the addChildView method for the sake of example:
LayoutInflater inflater;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//get the LinearLayout that you plan to add rows to
LinearLayout linearLayout = (LinearLayout)findViewById(R.id.linear_layout);
//get the LayoutInflater from the system
inflater = getSystemService(LAYOUT_INFLATER_SERVICE);
//call getNewChildView with whatever drawable id you want to place
//as the source. If you want to pass in other types, just change
//the parameters (e.g. Drawable, Bitmap)
linearLayout.addView(getNewChildView(R.drawable.my_image));
}
public RelativeLayout getNewChildView(int resId) {
//inflates a copy of your RelativeLayout template
RelativeLayout rl = (RelativeLayout)inflater.inflate(R.layout.relative, null);
//this assumes an ImageView in your RelativeLayout with an id of image
ImageView img = (ImageView)rl.findViewById(R.id.image);
img.setBackgroundResource(resId);
return rl;
}
EDIT: I couldn't even work out how to use the code tags properly sigh
Thank you both for your quick responses. I had something very similar in mind and in fact was on the same track and using the LayoutInflator. I simplified your example a little as I do not need to pass the id of a drawable around.
LayoutInflater inflater;
private void drawGuess() {
// The top level LinearLayout to add to
LinearLayout topLevel = (LinearLayout) findViewById(R.id.guessList);
// get the inflater`
inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
// add the view (based on stored data elsewhere)
topLevel.addView(getLatestGuess());
}
private RelativeLayout getLatestGuess() {
//inflates a copy of your RelativeLayout template
RelativeLayout rl = (RelativeLayout)inflater.inflate(R.layout.guess_layout, null);
//this assumes an ImageView in your RelativeLayout with an id of image
ImageView guessOne = (ImageView)rl.findViewById(R.id.guess1);
guessOne.setImageResource(R.drawable.red);
}
Running this code works, the catch is it only works the first time you call it. The second time you call getLatestGuess() it crashes. Removing the IDs in the XML (e.g. guess1) from all the child views of the RelativeLayout results in no more crashing. Unfortunately now I have a fairly useless RelativeLayout that I can no longer get at the child views of as they do not have IDs. Presumably, IDs are required to be unique.
I think you have to create an root element, and then add the new child.
Like this:
RelatoveLayout root = ....;
RelativeLayout toadd = inflate(your XML);
apply by code change depending of users input, for example:
toadd.setBackgroundResource(....);
and finally add the result to the root :
root.addView(toadd).
I really hope to help you!
Bye!