Question

I am new to Android Development and trying to create a sample application. Can anyone tell me whats wrong with following layout (activity_sample.xml)? –

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:orientation="vertical">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/app_name"
        tools:context=".SampleActivity" />
</LinearLayout>

On Build, I am getting following error –

error: Error parsing XML: unbound prefix    activity_sample.xml /Sample/res/layout  line 4  Android AAPT Problem

Answer 1

You haven’t declared the tools prefix in your XML. Try using:

<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="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/app_name"
        tools:context=".SampleActivity" />
</LinearLayout>