String types not allowed (at 'id' with value ' @id/bAdd')

Question

I am getting an error saying String types not allowed (at 'id' with value ' @id/bAdd')

• I've cleaned the project.

• Everything was working earlier, I don't what happened, causing this error.

   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" >
  
  <TextView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_centerVertical="true"
      android:text="Your total is 0"
      android:textSize="45dp"
      android:layout_gravity="center"
      android:gravity="center"
      android:id="@+id/tvDisplay"
      tools:context=".StartingPoint" />
  
   <Button 
      android:layout_width="250dp"
      android:layout_height="wrap_content"
      android:text="Subtract One"
      android:layout_gravity="center"
      android:textSize="20dp"
      android:id="+@id/bSub"
      />
  
  
  <Button 
      android:layout_width="250dp"
      android:layout_height="wrap_content"
      android:text="Add One"
      android:layout_gravity="center"
      android:textSize="20dp"
      android:id="+@id/bAdd"
  
      />
  

Answer 1

You can give your id as @+id/bAdd

instead of +@id/bAdd

Also edit in

android:id="@+id/bSub"
            ^^

instead of

android:id="+@id/bSub"
            ^^

Answer 2

+ Symbol must be after @ Symbol.

android:id="+@id/bAdd" to  android:id="@+id/bAdd"

 and also change

android:id="+@id/bSub" to android:id="@+id/bSub"

OR

you can declare is it

android:id="@id/bSub"

but you have to declare bSub value in ids.xml file located in values folder.

Example

<resources>
  <item type="id" name="bSub" />