Develop Reference

How to make a WhatsApp like `RecyclerView`?

This may be possible of duplicate question i have tried all things none of it works i need to make whatsapp like chat model using RecyclerView and at the bottom EditText and a Button bottom my problem is i can have EditText and bottom at the bottom but i need scroll to view that EditText and Button, what i should have when user enter that page EditText and Buttonb should appear without scrolling and one more problem there is lots of space between two items in thatRecyclerView` how to reduce that space let me post what i did so far:
My Recyclerview ChatLayout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<android.support.v7.widget.RecyclerView
android:id="#+id/constraint_recyclerview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:orientation="horizontal"
android:weightSum="4">
<EditText
android:id="#+id/message"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:hint="Enter Message"
android:lines="1" />
<Button
android:id="#+id/btn_send"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="3"
android:text="Send" />
</LinearLayout>
</RelativeLayout>
How to do this as am new for android development someone please help me!

You should change the android:height in layout that u use in your RecyclerViewAdapter to wrap_content
And also in your manifest
<activity
...
android:windowSoftInputMode="adjustPan"
...
></activity>

Their are many libraries out there.This library is a sample Android App which can be used as a starter application for a chat application.You can take reference or implemented this library in your project

check your row item(layout xml file) which is used in your viewholder. I think you have used match_parent in your parent view. Make it as wrap_content.
For that scrolling issue, check your code for smoothScrollToPosition(int). may be you have used this method in your code.

Soft Keyboard Hiding ActionBar while using adjustPan

I need to set visible all these three items
1. ActionBar
2. ListView
3. EditText (at Bottom)
When i click on EditText, it pushed the background image and squeezed it. i saw some tutorials and used android:windowSoftInputMode="adjustPan" that solved the squeezing issue but created a new one. When the SoftKeyboard appears, it also hides the ActionBar. I have visited many questions , but none of them was actually helpfull. IS there any way to set ActionBar always visible whatever happening on screen etc...
EDITED
The xml of fragment used to display the ListView and EditText is :
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/RelativeLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ListView
android:id="#id/android:list"
style="#style/ContactListView"
android:layout_width="match_parent"
android:layout_height="389dp"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:isScrollContainer="false" />
<TextView
android:id="#id/android:empty"
android:layout_width="match_parent"
android:layout_height="80dp"
android:layout_above="#+id/editText1"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:fontFamily="sans-serif-light"
android:gravity="center"
android:text="#string/no_contacts"
android:textAppearance="?android:attr/textAppearanceLarge" />
<EditText
android:id="#+id/editText1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentBottom="true"
android:background="#android:color/holo_blue_dark"
android:ems="10"
android:imeOptions="flagNoExtractUi"/>
</RelativeLayout>
Edited (2nd)
Snapshots are:

Try using android:windowSoftInputMode="adjustResize|stateHidden" in your activity tag.

I have the same problem as yours with EditText inside a Relative layout before, after searching several thread all over internet I have failed, but I solve it by experimenting on it through adding bottom_padding to the EditText which fixed it.

try this code to manifest file and activity to change layout.
android:windowSoftInputMode="stateAlwaysVisible|stateHidden"

Switch between button bars

I have a layout xml file:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#000000" >
<FrameLayout
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:layout_above="#+id/taoFooter">
<com.example.gamedice.DrawingPanel
android:id="#+id/taoCanvas"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:background="#000000" />
</FrameLayout>
<LinearLayout
android:id="#+id/taoFooter"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_alignParentBottom="true"
style="#android:style/Holo.ButtonBar">
<Button
android:id="#+id/roll1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="#string/roll1"
android:layout_weight="1"
style="#android:style/Widget.Holo.Button.Borderless"
android:onClick="rollTaoDice" />
<Button
android:id="#+id/roll2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="#string/roll2"
android:layout_weight="1"
style="#android:style/Widget.Holo.Button.Borderless"
android:onClick="rollTaoDice" />
<Button
android:id="#+id/roll3"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="#string/roll3"
android:layout_weight="1"
style="#android:style/Widget.Holo.Button.Borderless"
android:onClick="rollTaoDice" />
<Button
android:id="#+id/roll4"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="#string/roll4"
android:layout_weight="1"
style="#android:style/Widget.Holo.Button.Borderless"
android:onClick="rollTaoDice" />
</LinearLayout>
</RelativeLayout>
In addition to other items in the layout, this layout has a button bar consisting of four buttons at the bottom of the screen. Based on user input, I want to be able to replace this button bar with another predefined set of buttons, and then be able to change back later.
Since I know what the alternate set of buttons will be ahead of time, I thought it might be possible to use an alternate layout xml file, but I couldn't figure out how to do that. Can anyone give me some guidance?

You can add your second set of buttons in a layout like you did with the first, then in the layout xml file set the attribute android:visibility="gone" on the second layout. In your code you can call setVisibility(View.GONE) for one layout (e.g. taoFooter) and setVisibility(View.VISIBLE) on the other layout when you need to switch the buttons out.
Alternatively, if you easily want to add some animations you can add a ViewFlipper around your two alternate button layouts. Only the first one is visible by default. You can switch to the next layout with showNext(). Add calls to setInAnimation() and setOutAnimation() before that to enable the animations.

On an Android app layout how would I position a view so that it always appears half the distance below the middle?

I'm using a Relative layout as the root or parent container and I have two buttons to place inside this Layout. The buttons need to be placed one on top of the other. The problem is that I want to position these buttons so that they appear below the center of the view but not directly below. That is within the bottom half of the view I want the buttons to appear halfway along that half portion. I tried adding a the buttons as children of a RelativeLayout (that was centered in the middle) inside the parent RelativeLayout and that sort of achieves what I'm trying to but then the Eclipse complains with a warning stating that one set of Relative Layout tags is useless and that I should consider getting rid of it.
Then I tried giving a one of the buttons a top margin with respect to its parent and then placing the other button under the this button with the top margin. This seems to work until I try it out in other virtual devices and I find out that depending on the screen sizes and dimensions it might or might not appear where I want it to (especially not the case with tablet devices).
Ok, so then I'm not sure how to achieve what I want the right way (without warnings or errors). Here's my current code
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/default_real" >
<Button
android:id="#+id/sm_panel_email_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="300sp"
android:background="#drawable/info_view_email_button" />
<Button
android:id="#+id/sm_panel_web_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_below="#+id/sm_panel_email_button"
android:background="#drawable/info_view_web_button" />
</RelativeLayout>

How about using two layouts and the android:layout_weight attribute
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/default_real"
android:orientation="vertical" >
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1"/ >
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1" >
<Button
android:id="#+id/sm_panel_email_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:background="#drawable/info_view_email_button" />
<Button
android:id="#+id/sm_panel_web_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/sm_panel_email_button"
android:layout_centerHorizontal="true"
android:background="#drawable/info_view_web_button" />
</RelativeLayout>
</LinearLayout>

Crashes whenever I try to use a custom view object in XML layout

I have made myself a custom LinearLayout by the name of com.theflyingnerd.DroidMe.DiscreteNumericalRangeSelectorWidget that hosts a couple of spinner widgets. This custom LinearLayout inflates the following XML layout (You might not need to look at this too carefully but it's here for completeness):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<!-- Min value Spinner -->
<Spinner
android:id="#+id/discrete_numerical_range_selector_min_value_spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="left"
android:layout_weight="1" />
<TextView
android:id="#+id/to_text"
android:text="to"
android:textSize="14sp"
android:paddingLeft="10sp"
android:paddingRight="10sp"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="center"
android:layout_weight="0">
</TextView>
<!-- Max value Spinner -->
<Spinner
android:id="#+id/discrete_numerical_range_selector_max_value_spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="right"
android:layout_weight="1" />
I have placed one such object in the layout for one of my activities like so:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<include layout="#layout/search_form_section_generic_top"/>
<include layout="#layout/search_form_section_car_specific"/>
<com.theflyingnerd.DroidMe.DiscreteNumericalRangeSelectorWidget/>
<include layout="#layout/search_form_section_advanced_options" />
</LinearLayout>
The problem is that my app force closes immediately upon startup. I've checked by putting breakpoints in my custom LinearLayout that none of my custom code is even being run yet. Furthermore, if I copy-paste the layout code for my compound widget in place everything works, which indicates to me that I probably haven't left any important XML attributes out. What could be going wrong?

I fixed it by making the LinearLayout XML element in the widget layout into a merge instead, and moved all of the layout parameters out of the widget XML file and into the activity XML itself, thus replacing
<com.theflyingnerd.DroidMe.DiscreteNumericalRangeSelectorWidget/>
with
<com.theflyingnerd.DroidMe.DiscreteNumericalRangeSelectorWidget
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
If someone could tell me why this worked, it might help me and others doing it again, and you can take credit.

because you must specify the width and height of every view you use in you xml?