title: How to fix x Error parsing XML: unbound prefix in android
body: <p>I am creating an android application consists of login page, I created login page with two buttons but the xml showing an error called <strong>error: Error parsing XML: unbound prefix</strong> please tell me how to fix it.?</p>
  
  <p>This is my xml</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context="com.developer.milanandroid.Login" &gt;
  
      &lt;LinearLayout
          android:id="@+id/linearLayout1"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_alignLeft="@+id/linear_1"
          android:layout_alignRight="@+id/linear_1"
          android:layout_below="@+id/linear_1"
          android:layout_marginTop="56dp" &gt;
  
          &lt;TextView
              android:id="@+id/password"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="PASSWORD :"
              android:textAppearance="?android:attr/textAppearanceMedium" /&gt;
  
          &lt;EditText
              android:id="@+id/editTextusername"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:ems="10"
              android:inputType="textPassword" /&gt;
      &lt;/LinearLayout&gt;
  
      &lt;LinearLayout
          android:id="@+id/linear_1"
          android:layout_width="450dp"
          android:layout_height="wrap_content"
          android:layout_alignParentTop="true"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="108dp"
          android:orientation="horizontal" &gt;
  
          &lt;TextView
              android:id="@+id/username"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="USER NAME: "
              android:textAppearance="?android:attr/textAppearanceMedium" /&gt;
  
          &lt;EditText
              android:id="@+id/editTextpassword"
              android:layout_width="350dp"
              android:layout_height="wrap_content" /&gt;
      &lt;/LinearLayout&gt;
  
      &lt;LinearLayout
          android:layout_width="450dp"
          android:layout_height="wrap_content"
          android:layout_alignLeft="@+id/linearLayout1"
          android:layout_below="@+id/linearLayout1"
          android:layout_marginTop="63dp" &gt;
  
          &lt;Button
              android:id="@+id/clear"
              style="?android:attr/buttonStyleSmall"
              android:layout_width="225dp"
              android:layout_height="wrap_content"
              android:text="clear" /&gt;
  
       &lt;!--     &lt;Button
              android:id="@+id/Login"
              style="?android:attr/buttonStyleSmall"
              android:layout_width="225dp"
              android:layout_height="wrap_content"
              android:text="login" /&gt;--&gt;
          &lt;com.developer.milanandroid.buttonlib.ActionProcessButton 
              android:id="@+id/btnSignIn"
              android:layout_width="match_parent"
              android:layout_height="48dp"
              android:layout_marginBottom="16dp"
              android:text="Sign_in"
              android:textColor="@android:color/white"
              android:textSize="18sp"
              custom:pb_colorComplete="@color/green_complete"
              custom:pb_colorNormal="@color/blue_normal"
              custom:pb_colorPressed="@color/blue_pressed"
              custom:pb_colorProgress="@color/purple_progress"
              custom:pb_textComplete="Success"
              custom:pb_textProgress="Loading" /&gt;
  
      &lt;/LinearLayout&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>