Android Studio Unknown attribute in xml and Namespace not found

Question

I recently got this warning in Layout and manifest files. I have attached those images below just check those in case for further clarification.

The problem is I'm getting Namespace " is not bound warning and I cannot use the autocomplete code for xml files which can be generally used in android studio.Please help for this issue. The unknown xml attribute warning is displayed for each and every android attribute.

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
              xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent"

              >
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/blue"

            >
    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="text"
        android:textColor="@android:color/white"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:layout_margin="10dp"
        android:layout_above="@+id/editText"
        android:layout_alignLeft="@+id/editText"
        android:layout_marginBottom="15dp"/>
    <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="number"
            android:ems="15"
            android:padding="10dp"
            android:id="@+id/editText" android:layout_gravity="center"
            android:layout_centerInParent="true"
            android:background="@color/white"/>
    </RelativeLayout>

</RelativeLayout>

Answer 1

It is very simple. Delete .caches file:

1. Just close your AS.
2. Go to .AndroidStudio3.2 folder.
3. Delete the Caches file (path is: C:\Users\user\AppData\Local\Google\AndroidStudio2020.3\caches)
4. Restart your AS.
5. Enjoy.

NB: This Solution is for Android Studio 4+

if you are using Android Studio 3+ then delete cache from the following path

C:\Users\user.AndroidStudio3.x\system\caches

Answer 2

Ran into the same issue. I think that there's some specific bug related to this for Android Studio 3.2. My solution on Windows was to delete everything withing the cache/ folder in the .AndroidStudio3.2/ folder.

I tried everything that other's mentioned, sync gradle files, invalidate cache, removed the whole project and added it again. The only thing that worked for me was reinstalling the Android Studio. The second time that happened to me I decided to look for a better solution than reinstalling the whole Android Studio. Started playing with the cache files and figured out that deleting everything under the cache/ folder in the configuration folder of the Android Studio solved the problem.

Answer 3

This is problem with Android studio caches.

most probably syncing the project with gradle files will help

If no, you can manually delete cached files located on $HOME/.AndroidStudio3.2/system/caches and rebuild your project.

UPDATE: Gradle sync cache isses fixed in android studio 3.5 version. Update android studio to latest version can help.

Answer 4

100% Working

Do this two steps:

1. Go to folder where you android studio caches are located. I have android studio 3.6.3 For me it's C:\Users\User_folder\.AndroidStudio3.6\system\caches.
2. Go to the folder where you android studio projects are located. Open the project >then .idea folder and delete the caches. For me its C:\Users\User_folder\AndroidStudioProjects\Project_name\.idea\caches.