parent as relative layout i have textview (for title) and linearlayout for viewgroup in that by id am accessing viewgroup. and inside child linear layout i have textview and relative layout for image and textview .after viewgroup in my above linear layout i want to access one viewgroup how to do that?
Did not understand what do you want to achieve, but you must remember, that layout structure in Android is a tree. Every two View Groups can have a parent View Group above them. So just instantiate a root layout and then place any number of View Groups you need there. Good luck!
Related
I'm new to Android development so this might be an obvious question, but I've looked at multiple sources and can't find the answer. If you put widget elements inside a layout element then the parent of those widget elements is the layout element, right? So what is the parent element of the layout? Because in the default generated file, activity_main.xml (for the layout), there is the attribute android:layout_width="match_parent" for the topmost constraint layout element. So, what is the parent of this constraint layout element?
Your ConstraintLayout is the root layout of your Activity but it is just part of a layout created by the system.
You can for example get the reference of the parent layout of your ConstraitLayout:
ViewGroup layoutRoot = findViewById(android.R.id.content);
When you set match_parent, your View (a Layout is a ViewGroup which is just a View) will try to fill the space available in its parent layout. So, in a certain way, it just tell to how much your view can grow in the X/Y-axis. In your case, your ConstraintLayout will grow in order to match that android.R.id.content
Of course, there's one View on the top of the stack (probably the decorView of your Window) which is created by the System and is assuming whole area available on the Window created by the system.
Basically we use parent layout as Linear Layout/Relative Layou/ConstraintLayout/Frame Layout etc. So all are classes which extends ViewGroup. Please refer to Google developer documentation for better understanding.
Read this -
https://developer.android.com/reference/android/view/ViewGroup.html
match_parent is a fixed value for views to stretch according to their parents.
For example let's say you have a Textview inside a RelativeLayout. If the Textview is set to match parent then it would stretch according to its parent/rootview which is the Relative layout.
So basically it would have as the same height and width as the parent layout.
How to create a whole layout (Relative/Linear) multiple times in Android? I want the same layout to be created multiple times inside a horizontal scroll view.
You can use RecyclerView for Horizontal scrolling-
or-
Take horizontal scrollview reference in java code by findViewById.
Create one other xml for view which you want to display multiple
time.
inflate that view by getlayoutinflator. Create a loop in
view.
create a linearlayout at runtime and add those view to it by add
view
and add linearlayout to horizontal scroll view. by addview()
take a idea and modify the below code
scrollview = findViewByID(scrollview);
LinearLayout ll = new LinearLayout(this);
for(your loop){
View v= getLayoutInflator().inflate(R.layout.xml);
ll.addView(v);
}
scrollview.addView(ll);
Either you need to add inflated child views to the root view like below
RelativeLayout rootView = (RelativeLayout)findViewById(R.id.rootView);
View child = getLayoutInflater().inflate(R.layout.child, null);
rootView.addView(child);
OR you can define and include that layout multiple times inside other.
Check this link http://developer.android.com/training/improving-layouts/reusing-layouts.html
Include your reusable layout like this
<include
android:layout_width="fill_parent"
android:layout_height="wrap_content"
layout="#layout/reusabelLayout" />
I'm a bit confused, when I declare a layout in XML, and I call the:
R.layout.idname
is this considered the ViewGroup?
It depends on the widget you declared inside your layout. For instance you can declare a single TextView inside your layout. TextViews are views, not ViewGroup. If you declare a LinearLayout for instance, it will be a ViewGroup. If you take a look to the documentation you can see the direct and indirect subclass of ViewGroup
is this considered the ViewGroup?
No, this is the complete layout file.
Are layouts same as ViewGroups?
No, one is the file. A ViewGroup would be any View such as a RelativeLayout, LinearLayout, etc... that holds other Views.
From the docs
A ViewGroup is a special view that can contain other views (called children.)
Not really. It depends on which xml layout you have given R.layout.idname to.
TextView, ImageView, EditText for examples are NOT viewgroups.
FrameLayout, RelativeLayout, LinearLayout etc are considered viewgroups.
A clue is in the name really... viewgroup. a view that can be a grouping of views.
No, Layouts are not same as ViewGroups. While every Layout is a ViewGroup, there are ViewGroups that aren't layouts (e.g. ViewPager, ScrollView). Regarding an XML file in R.layout, it depends on the root element of the XML: if for example it's a LinearLayout - you'll be able to cast it to ViewGroup, if it's an ImageView - it is considered a View.
View group: is a combination of views
Layouts: how views should sortup
View group has views inside it, but how the views should be arranged, the arrangement of views is known as layouts.
For examples, linear layout and relative layout are both layout and view group because they have views inside and the arrangement of views in them are known as layouts.
I want to set a ScrollView for some views. I need to merge some view into one view and add to ScrollView.
The three views are listView, custorm view and Gallery.
Who knows how to merge the three views into a blank view and display?
In XML you can structure your app like the following snippet:
<ScrollView>
<LinearLayout>
<CustomView/>
<ListView/>
<Gallery/>
</LinearLayout>
</ScrollView>
Alternatively in code, you can do it like so:
ScrollView SV = (ScrollView) findViewById(R.id.my_scrollview);
LinearLayout LL = (LinearLayout) findViewById(R.id.my_linear_layout);
LL.addView(my_customView)
LL.addView(my_istView)
LL.addView(my_gallery)
SV.addView(LL);
hope that gives you some pointers in how to achieve what you'd like to
You can create those objects and assign them inflated elements. I mean, if the listView is in listView.xml you can inflate it with getLayoutInflater().inflate(R.layout.listView,null) and put in a ListView object. Then you can add it to a ViewGroup.
Inflate the ScrollView, you can create programmatically too. ScrollView scroll=new ScrollView(this). Don't forget adding LayoutParams to the view if you do it programmatically.
ViewGroup scrollView = (ViewGroup) getLayoutInflater().inflate(R.layout.scrollView, null);
Then you inflate or create the other views the same way. Or you can get it from an activity with findViewById(R.id.idOfView1).
Finally just add the views you've created, inflated... with scrollView.addView(View child).
You need a ViewGroup to add views as childs.
I have a layout xml file with a linear layout. One of the children is again a ViewGroup Relative layout. In my java code i want to change the width of this child Viewgroup for my requirements. I tried this
enter code here
ViewGroup childViewGroup = (LinearLayout)findViewById(childViewGroup);
LayoutParams l = childViewGroup.getLayoutParams();
l.width = 360;
childViewGroup .setLayoutParams(l);
I couldn't do this because findViewById(childViewGroup) doesn't fetch ViewGroups it does only for Views.
Note: I cant define a whole new layout.xml for this minor requirement since it is huge layout file and might cause performance overhead. I wanted to just change the width of the child view group in my java activity code.
Thanks in advance for your help.
ViewGroup is a subclass of View so findViewById should work fine. You're casting the result to LinearLayout, is the childViewGroup a LinearLayout or RelativeLayout as you specified in the question? – codelark Oct 6 at 23:21
You may use ViewStubs.
You can find a reference here:
http://developer.android.com/resources/articles/layout-tricks-stubs.html