What Is the Class R in Android

Understand the R class in Android

R.java is the dynamically generated class, created during build process to dynamically identify all assets (from strings to android widgets to layouts), for usage in java classes in Android app. Note this R.java is Android specific (though you may be able to duplicate it for other platforms, its very convenient), so it doesn't have much to do with Java language constructs. Take a look here, for more details.

What is the class R in Android?

R is a class containing the definitions for all resources of a particular application package. It is in the namespace of the application package.

For example, if you say in your manifest your package name is com.foo.bar, an R class is generated with the symbols of all your resources in com.foo.bar.R.

There are generally two R classes you will deal with

1. The framework resources in android.R and
2. Your own, in your namespace

It is named R because that stands for Resources, and there is no point in making people type something longer, especially since it is common to end up with fairly long symbol names after it, that can cause a fair amount of line wrapper.

What is R class in android

Your question is duplicate of Understand the R class in Android

When your application is compiled, aapt generates the R class, which
contains resource IDs for all the resources in your res/ directory.
For each type of resource, there is an R subclass (for example,
R.drawable for all drawable resources) and for each resource of that
type, there is a static integer (for example, R.drawable.icon). This
integer is the resource ID that you can use to retrieve your resource.

I got this detail from the below link ,check this once for more details :
http://developer.android.com/guide/topics/resources/accessing-resources.html

What does R.id.myView refer to?

R - R.java is an auto-generated file by aapt (Android Asset Packaging Tool) which contains resource IDs for all the resources of res directory.

public final class R 
extends Object 

.id - Find view using its id "defined by you"

public static final class R.id 
extends Object 

myView - It is the view that you defined using the android:id="@+id/your_view" attribute in your XML file.

So, finally we can find or identify any view using R.id.your_view.

diferrence between R & android.R class

R.layout.*, R.id.*,in fact any R.something without the android.- part in front of it refers to some resource in your resources folders, e.g. drawables, strings, layouts, ids of widgets etc. android.R.* refers to standard android items that come shipped with your SDK

the R.java file in android studio 3.4

Try this:

\app\build\generated\not_namespaced_r_class_sources\debug\processDebugResources\r\<package_name_tree>\R.java

package_name_tree means : If package is a.b.c
the goto: /a/b/c/R.java

Android & Java: what is the odd object called `R`?

R is a static class that lists all your resources (usually defined in XML, but all available in your res folder).

For more info: Understand the R class in Android

edit: According to here: The android java class cannot recognize the R file
one of your classes might actually be importing the R.java class. Never do that. If there are imports of that class, remove them.

Also, You might to clean the project (project - clean - clean project)

Android studio hides R class

You can find R class by searching it with "shift + cmd + o" or "double shift".

I guess new android studio update directs to the xml source of the resource.

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