Develop Reference

How do i change the backgroud color of a button in kotlin [duplicate]

This question already has answers here:
How to add button tint programmatically
(22 answers)
Android button background color
(12 answers)
Closed 2 years ago.
I am new to kotlin programming and i can't resolve the problem that i am facing in android studio. I followed a course on youtube, and at one point the video teaches you how to build an actual app. I want to change the backgroud color of a button that i made but whatever i do, the button keeps having the color purple.
I tryed this 2 methods:
android:background="#android:color/white"
android:background="#FFFFFF"
Can you help me guys, i would be really thankful
the entire code is: ( please do not mind the names i chose for the colors, im romanian)
<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:id="#+id/padding"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/backgroundColor"
android:gravity="center_horizontal"
android:orientation="vertical"
android:padding="16dp"
tools:context=".MainActivity"
>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:background="#android:color/white"
android:backgroundTint="#color/white"
android:text="Selecteaza data"
android:textColor="#color/culoarePrimara"
android:textSize="20sp"
android:textStyle="bold"
/>
</LinearLayout>
This is the color:

instead of android:background="#color/backgroundColor"
use: android:backgroundTint="#color/backgroundColor"

For button background color either use custom style or android:backgroundTint="#color/white" (or your preferred color)

You can use:
<Button
app:backgroundTint="#color/..."/>
May be you are using a Theme.MaterialComponents.* theme and the default background color of the Button (which is replaced by a MaterialButton) is the colorPrimary defined in your app theme.

Overdraw issue in fragment layout with both background color and theme existing

Hi I am a newbie to Android Programming using AS. This should be a common/easy problem but I have not found a solution so far.
I was creating left_ and right_fragments tags in activity_main.xml for tablets, in which I wanted to have a background color in right_fragment(temporarily set to #ffffff and keep left_fragment as default). Then the Android Lint warned that I got an Overdraw: Painting regions more than once on the right_fragment:
I tried to create a new theme:
<style name="NoBgTheme" parent="android:Theme.Material.Light.DarkActionBar">
<item name="android:windowBackground">#null</item>
</style>
and added android:theme="#style/NoBgTheme" to right_fragment.xml, but it did not work.
Screenshot of this app w/ Debug GPU Overdraw enabled.
If I change android:theme= from "#style/AppTheme" to "#style/NoBgTheme" in AndroidManifest.xml, it worked, but all other layouts lost their backgrounds.
Any idea how to fix this OVERDRAW? Thx in advance.
activity_main.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:baselineAligned="false"
android:orientation="horizontal">
<fragment
android:id="#+id/left_fragment"
android:name="jerryc05.fragmenttest.LeftFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1" />
<fragment
android:id="#+id/right_fragment"
android:name="jerryc05.fragmenttest.RightFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1" />
</LinearLayout>
left_fragment.xml is so simple that we can just ignore it.
right_fragment.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:theme="#style/NoBgTheme"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#ffffff">
<TextView
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="This is right fragment"
android:textSize="20sp"
tools:ignore="HardcodedText" />
</LinearLayout>
AndroidManifest.xml remains unchanged.
MainActivity.java remains unchanged.

A little bit of overdraw will happen. You need to set the nobgtheme to your main activity if you want to fix the overdraw on your left fragment and right fragment display. If this only happens during tablet layouts you can check to see if this is a tablet layout being used and set the no background theme at runtime using methods described here: How to change current Theme at runtime in Android

Alright, I got an alternative solution.
I added android:theme="#style/NoBgTheme" after <activity android:name=".MainActivity" before >.
Then I manually specified android:background="#f0f0f0" and android:background="#ffffff" to left_ and right_fragment.xml respectively.
It worked so well!!!
But the Android Lint Warning still exists...(is this a bug or still my fault?)

Ripple Effect Duration in Android XML

I am Learning Material Design. I tried ripple effect on button using this gradle
dependencies {
compile 'com.github.traex.rippleeffect:library:1.3'
}
from this https://github.com/traex/RippleEffect link
there are many attribute which are not working
such as
app:rv_rippleDuration="1200"
app:rv_color="#d3d3d3"
I have event on button and ripple effect but when I click on button method is get called. What I want is first ripple effect should get complete then action should occur.
XML code
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp">
<com.andexert.library.RippleView
android:id="#+id/ripple1"
android:layout_width="match_parent"
android:layout_height="match_parent"
rv_centered="true"
app:rv_rippleDuration="1800"
app:rv_color="#000000">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="New Button"
android:id="#+id/fromDateButton" />
</com.andexert.library.RippleView>
</LinearLayout>
user cannot experience animation.

You need to add xmlns:app="http://schemas.android.com/apk/res-auto" as an xmlns in your RippleView before using the app resource.

Problem in the example on the page of description in GitHab.
Change
rv_centered="true"
to
app:rv_centered="true"
and all will be done.
All attribute of ReppleView must contain app:

Change background color of tabBar in v4 viewPager

I'm building an app for Android using a viewPager, and things work just fine on a phone, but on a tablet there is a gray background on both sides of the tabs, the need is to change this background color to white.
On a phone it Looks just fine, sorry for ugly censoring
On a tablet the gray background appears
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:id="#+id/pager"
android:layout_width="match_parent" android:layout_height="match_parent"
tools:context=".MainActivity"
android:background="#color/white" />
The styles I've tried to override are the ones below, I've tried to set most properties that contain the word "color" to white, but nothing has worked.
android:actionBarStyle
android:actionBarTabStyle
android:actionBarTabBarStyle
I base my theme on Theme.AppCompat.Light
I've also tried setting the background of the viewPager and actionBar in code, but it did nothing, I'm guessing it's a subview I need to get to. I've been googling my heart out but I can't find anything about this specific styling.

You can do something like this.
<?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"
tools:context=".MainActivity"
android:background="#android:color/white" >
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/white" />
</RelativeLayout>

Android elevation property not working

Since upgrading to SDK 21 I've been trying to use the elevation property but it never seems to work.
I want to elevate a frame above others so I'm setting the following
android:elevation="4dp"
but there's no sign of shadow. I've tried buttons and framelayouts but not got any elevation
So here's the full tag
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/panel_card"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#ffffff"
android:elevation="4dp"
>
Am I missing something else I need to add

Make sure that the background for the container holding the FrameLayout is not transparent.

According to this Z = Elevation + TranslationZ
so try this:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/panel_card"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#ffffff"
android:elevation="4dp"
android:translationZ="4dp">

You need to add a background to it something like:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/panel_card"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="4dp"
android:background="#drawable/dialog_background">
Instead of using white color. Otherwise the shadows won't work. Also, is it not necessary to use android:translationZ attribute since that just adds to the elevation, but is not required if you don't want animation.