Develop Reference

What exactly is runtimeOnly on androidx.appcompat:appcompat

I'm working with old version of appcompat, but error after migrate to androidX.
implementation 'com.android.support:appcompat-v7:28.0.0'
Should i use implementation instead of runtimeOnly ?

After androidx migration your dependency would have been changed to following:
implementation "androidx.appcompat:appcompat:1.5.1"
If above is already present in your build.gradle then you can safe remove appcompat-v7 dependency.
As far as using implementation or runtimeOnly it totally depends upon dependency usage. If its usage in compile time then use implementation or if this just require in runtime use runtimeOnly.

To get your answer please refer to the link: Dependency configurations
According to the description mentioned in above link:

error: package android.arch.lifecycle does not exist

I am getting error: package android.arch.lifecycle does not exist and i tried to resolve it,
i used below links : but none of these resolve it:
Failed to resolve: android.arch.lifecycle:extensions:1.0.0-alpha1 android studio 3.0
Could not resolve android.arch.lifecycle:extensions:1.1.0
i have below dependencies :
// Room components
implementation "android.arch.persistence.room:runtime:$rootProject.roomVersion"
annotationProcessor "android.arch.persistence.room:compiler:$rootProject.roomVersion"
androidTestImplementation "android.arch.persistence.room:testing:$rootProject.roomVersion"
// Lifecycle components
implementation "android.arch.lifecycle:extensions:$rootProject.archLifecycleVersion"
annotationProcessor "android.arch.lifecycle:compiler:$rootProject.archLifecycleVersion"
Recently I got this link:
https://developer.android.com/jetpack/androidx/releases/lifecycle#java
which says : The APIs in lifecycle-extensions have been deprecated. Instead, add dependencies for the specific Lifecycle artifacts you need.
Does this mean now I need to use individual packages?

The android.arch packages have been deprecated, try using androidx packages instead. Also make sure you've added google() in your build.gradle.

Finally i got the answer.
android.support is deprecated , i migrated to androidx via following links:
https://medium.com/androiddevelopers/migrating-to-androidx-tip-tricks-and-guidance-88d5de238876
https://developer.android.com/jetpack/androidx/migrate
And at last if you get error like buttler knife/ (or any third party lib) not resolved, find android x compatible version
i used:
// butter knife
implementation 'com.jakewharton:butterknife:10.0.0'
annotationProcessor 'com.jakewharton:butterknife-compiler:10.0.0'

androidx.lifecycle.DefaultLifecycleObserver not found

I am having a problem where my build cannot find one of the androidx classes, specifically:
androidx.lifecycle.DefaultLifecycleObserver
Here are my gradle deps:
annotationProcessor "androidx.lifecycle:lifecycle-compiler:2.0.0"
implementation "androidx.lifecycle:lifecycle-runtime:2.0.0"
implementation "androidx.lifecycle:lifecycle-extensions:2.0.0"
I don't have any other problems getting androidx classes, just this one.
I have tried to invalidate caches in android studio and restart with no luck. Also a build clean as well as a gradle sync.
I verified here:
https://developer.android.com/jetpack/androidx/migrate
The mapping of that class from the support library to androidx:
android.arch.lifecycle.DefaultLifecycleObserver ->
androidx.lifecycle.DefaultLifecycleObserver
Any ideas on why this is happening?

I think that's because you're missing one dependency:
implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"
Get the latest version of lifecycle-common-java8 here
See the documentation:
If you use Java 8 Language, then observe events with
DefaultLifecycleObserver. To include it you should add
"androidx.lifecycle:lifecycle-common-java8:" to your
build.gradle file.

How to take webkit in use from androidx support library

How do I get webkit in use from androidx support library?
I have added this for example:
import androidx.webkit.WebSettings;
but it's not resolved
I have added to gradle
implementation 'androidx.appcompat:appcompat:1.0.2'
and to gradle.properties
android.enableJetifier=true
android.useAndroidX=true

I figured this out just needed to add webkit as separate dependency in gradle.
implementation 'androidx.webkit:webkit:1.0.0'

Import new Android Design Support library

Hi i'am trying to import the new android support library like this com.android.support:support-design:22.0.0 but i got this error after sync the gradle : failed to find

You have to update your Android Support Repository in SDK Manager, then just add this dependency to your build.gradle:
compile 'com.android.support:design:22.2.0'
com.android.support:support-design:22.0.0 is wrong.

dependencies {
implementation 'com.android.support:design:28.0.0'
}

New Android Design Libraries usually start with androidx word, such as:
AppCompat androidx:
implementation 'androidx.appcompat:appcompat:1.2.0'
CardViex androidx:
implementation 'androidx.cardview:cardview:1.0.0'
However be careful because everything is not start with androidx. For example, old design dependency is:
implementation 'com.android.support:design:28.0.0'
But new design dependency is:
implementation 'com.google.android.material:material:1.1.0'
Recyclerview dependency is:
implementation 'androidx.recyclerview:recyclerview:1.2.0'
So, you have to search and read carefully.

The docs has it wrong.
It should actually be 'com.android.support:design:22.2.0'
as mentioned in their official blog.

With gradle 3 it should be:
dependencies {
implementation 'com.android.support:design:27.0.2'
}

You can use:
compile 'com.android.support:design:22.2.0'
I built a complete example. I hope it helps! https://github.com/erikcaffrey/AndroidDesignSupportLibrary
Remember now is available!
Android Support Library, revision 22.2.1 (July 2015)

ctrl+alt+shift+s in the androidstudio window...
project structure window will appear..
click the app in the menu bar at the left then click dependencies..
then add `com.android.support:design:26.1.0

implementation 'com.android.support:design:28.0.0'
Click on 'File' --> 'Project Structure' (or CTRL+ALT+SHIFT+S) --> Select 'Dependencies' --> Click on '+' in the 'All Dependencies' section --> Select '1.Library Dependency'--> here you can search for any library to implement in your android studio project.

i was facing the same problem actually this is old one.
Just replace it with the following code:
implementation 'com.google.android.material:material:1.1.0'