Develop Reference

Android Studio, cant add a button to viewpager

Im totally new to android studio and tried creating a simple app. When creating the project, I chose "Tabbed Activity" which is working as intended.
But when I go to the Design manager and add a button, it is not possible to move it using the mouse because it disappears as soon as I try to move it.
As said, Im totally new to this and written/youtube guides didn't help me either.
Feel free to ask for any information if you need it.
Thanks in advance.
EDIT:
This is my activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/Theme.RiseUpdates.AppBarOverlay"
android:background="#color/light_gray">
<TextView
android:id="#+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:minHeight="?actionBarSize"
android:padding="#dimen/appbar_padding"
android:text="#string/app_name"
android:textAppearance="#style/TextAppearance.Widget.AppCompat.Toolbar.Title" />
<com.google.android.material.tabs.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
app:tabSelectedTextColor="#color/rise_orange"
app:tabTextColor="#color/white"
app:tabBackground="#color/light_gray" />
</com.google.android.material.appbar.AppBarLayout>
<androidx.viewpager.widget.ViewPager
android:id="#+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/dark_gray"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Your ViewPager have attributes:
android:layout_width="match_parent"
android:layout_height="match_parent"
It means, that it takes all space in your CoordinatorLayout. And as the result, you button is hided under the ViewPager.

Android Studio is not showing Design Preview But Application is running

I have updated my android studio. In my layout preview my design is not showing it says
NOTE: One or more layouts are missing the layout_width and layout_height attributes, required in most layouts.
OR: Automatically add all missing attributes. There is no error in application. It's running well. I have uninstalled my android studio but same issue occurred. In all my projects occurs the same issue.
I have updated SDK as well.
Here is layout.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:local="http://schemas.android.com/apk/res-auto"
android:id="#+id/coordinate_layout_sheet"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar_series"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/colorPrimaryDark"
local:popupTheme="#style/ThemeOverlay.AppCompat.Light"
local:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
</android.support.v7.widget.Toolbar>
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
</LinearLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="gone">
<ProgressBar
android:id="#+id/pb_product"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:visibility="visible" />
<TextView
android:id="#+id/tv_no_record"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:gravity="center"
android:text="No record Found"
android:textSize="18sp"
android:visibility="visible" />
</RelativeLayout>
<!-- <android.support.v4.widget.NestedScrollView
android:id="#+id/bottom_sheet_registration"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#EEEEEE"
android:clipToPadding="true"
android:visibility="gone"
app:layout_behavior="android.support.design.widget.BottomSheetBehavior">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="14dp"
android:orientation="vertical">
<include layout="#layout/bottomsheet" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>-->
<View
android:layout_width="match_parent"
android:layout_height="60dp" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true">
<Button
android:id="#+id/btn_add_tocart"
style="#style/Base.Widget.AppCompat.Button.Colored"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:layout_weight="1"
android:backgroundTint="#863029"
android:text="Add To Cart"
android:textAllCaps="false" />
</RelativeLayout>
</RelativeLayout>
</android.support.design.widget.CoordinatorLayout>

This happens to me sometimes. What I do to fix this is to check styles.xml from res folder and check that the style AppTheme is correctly defined.
For example, if I want my app style to be without action bar, I use this as AppTheme:
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
...
and add required items such as colorPrimary etc.
Then after rebuilding the gradle I usually can see my layout design again

One of the possibility is that your Theme changes. Try changing it to Material -> Dark in the Preview view.
Link to the similar topic:
android studio preview not displaying? version 1.5.1

Umano SlidingUpPanel not working in CoordinatorLayout

I'm using Umano SlidingUpPanel to set a view like the following:
But no matter what I do, It can't be shown hidden. Instead, it's "peeking":
I need it to hide completely. This is my XML resource
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_height="match_parent"
android:layout_width="match_parent"
xmlns:sothree="http://schemas.android.com/tools"
android:id="#+id/coordinator_layout"
tools:context="com.pocket.poktsales.activities.InventoryActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<ProgressBar
android:id="#+id/progressBar"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical|center_horizontal"
app:layout_anchorGravity="center_vertical|center_horizontal" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#drawable/ic_box_add" />
<com.sothree.slidinguppanel.SlidingUpPanelLayout
android:layout_height="wrap_content"
android:layout_width="match_parent"
sothree:umanoDragView="#+id/sliding_up_panel"
android:gravity="bottom"
sothree:overlay="false"
sothree:umanoPanelHeight="0dp"
sothree:umanoParalaxOffset="100dp"
sothree:umanoShadowHeight="4dp">
<include
android:id="#+id/include"
layout="#layout/content_inventory" />
<include android:id="#+id/sliding_up_panel"
layout="#layout/content_product_detail"/>
</com.sothree.slidinguppanel.SlidingUpPanelLayout>
</android.support.design.widget.CoordinatorLayout>
I have tried:
use 0 dp for panel height, no results. Actually it'snot even affected by that attribute no matter what's the value.
Wrap it inside a frame Layout with no result.
Can anyone help me to hide it completely?

In my particular case, I added the panel height programatically:
panel.setPanelHeight(0);
And now it's working!

RecyclerView and Toolbar, can't scroll bottom item into view

EDIT: See Using the Master/Detail template in ViewPager Fragments (download link) for full code
I have a toolbar and a recyclerView. When the layout is first inflated the last item of the recyclerView is out of the scroll-able region of the screen and is therefore not visible. After rotating the item appears. It is apparent that the toolbar is pushing the recyclerView outside the boundaries of the screen. If I add padding to the bottom of the recyclerView with the height of the toolbar the issue is resolved BUT only for the initial inflation of the layout. After rotation I am left with a gap on the bottom of the screen. I'm using sdk 23.
A possible workaround would be to programmatically remove the padding after the very first inflation of the layout. I assume I could use:
onCreateView(){ if (onSaveInstanceState != null) removePadding();}
However, I'd rather not have to do a dodgy work-around.
My app is basically exactly the same as the Master/Detail-flow template supplied in Android Studio, except that I use fragments and a single Activity. There is no such issue in the template.
Any ideas?
fragment_item_list.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<FrameLayout
android:id="#+id/frameLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<include layout="#layout/item_list" />
</FrameLayout>
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
item_list.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/item_list"
android:name="com.idragonit.scrolltabs.ItemListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="16dp"
android:layout_marginRight="16dp"
app:layoutManager="LinearLayoutManager"
tools:context="com.idragonit.scrolltabs.ItemListActivity"
tools:listitem="#layout/item_list_content" />
item_list_content.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="#+id/id"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="#dimen/text_margin"
android:textAppearance="?attr/textAppearanceListItem" />
<TextView
android:id="#+id/content"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="#dimen/text_margin"
android:textAppearance="?attr/textAppearanceListItem" />
</LinearLayout>
snippet of ItemListFragment.java
Toolbar toolbar = (Toolbar) root.findViewById(R.id.toolbar);
toolbar.setTitle("List");

I added:
android:layout_gravity="fill_vertical"
android:layout_marginBottom="?attr/actionBarSize"
to item_list.xml. The issue persists. The first time the layout is inflated it shows the bottom element as expected. After rotating to landscape and back to portrait it leaves a margin the size of the actionBar at the bottom of the screen.
This issue does not happen in the Master/Detail-flow template available in Android Studio and the code for item_list.xml, item_list_twopane.xml and activity_item_list are exactly the same as the code used in item_list.xml, land/item_list.xml and fragment_item_list.xml in my project. Yet, as the attached images show, the preview of the AppBar shows the flexible space in the Android template but not my code.
EDIT: When I click on the reference for "?attr/actionBarSize" in the template it navigates to a different line in android SDK's values.xml, which starts with <declare-styleable name="AppCompatTheme">. The same line of code in my app references a different line starting with<declare-styleable name="Theme">.
Screenshots:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns: android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
android:orientation="vertical">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<android.support.v7.widget.RecyclerView
android:id="#+id/item_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp"
android:scrollbars="vertical" />
</LinearLayout>
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_gravity="bottom|right"
android:layout_marginBottom="#dimen/activity_vertical_margin"
android:layout_marginRight="#dimen/activity_horizontal_margin"
android:src="#drawable/ic_add"
app:backgroundTint="#color/colorPrimary" />
</android.support.design.widget.CoordinatorLayout>

You must add
android:layout_paddingBottom="?attr/actionBarSize
Instead of
android:layout_marginBottom="?attr/actionBarSize
This works for me

Putting content below AppBarLayout in a CoordinatorLayout

I'm very new to Android and I intended to post this to the Android Developers - Google Groups but they seem to say that newbies need to post to Stack Overflow. So I'm here.
I downloaded the most recent version of Android Studio 1.4.1 yesterday, and I followed the instructions on Building Your First App. I did everything up to Starting Another Activity. It seems these instructions are a bit old i.e. for a previous version of the SDK, because they do not reference CoordinatorLayout and AppBarLayout though they appear in the code if you follow the steps. Obviously, I did make minor changes in the code to get this app to work, but not completely.
My Problem: If you look at the images at the bottom of Starting Another Activity you will see that both of them have the title My First App. In my modifications of the code, I could not get this title on both the images/screens. (I should mention that I want to use the more recent version of AppBarLayout and CoordinatorLayout)
Let's focus on the first screen, the activity_my.xml is
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".MyActivity">
<include layout="#layout/content_my" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
As mentioned at the bottom of Building a Simple User Interface the content_my.xml looks like:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage"/>
</LinearLayout>
Is there anyway, I can add the AppBarLayout to the activity_my.xml. I have tried something like:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".MyActivity">
<android.support.design.widget.AppBarLayout
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="#layout/content_my" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
The problem with this is that the content in content_my.xml goes behind the Toolbar of AppBarLayout rather than below it. Any ideas how to fix this issue?

Layouts in a CoordinatorLayout need to define a layout_behavior. Change your content to this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
>
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage"/>
</LinearLayout>