title: XML/Android: No resource found that matches the given name error
body: <p>I looked up some question posted here, but nothing worked so far, so I figured I'd ask my own. I keep getting the "No resource found that matches the given name(at 'text' with value '@strings/button_name')." error for this .xml file(error is in the last line of the Button tag):</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"
      android:paddingBottom="@dimen/activity_vertical_margin"
      android:paddingLeft="@dimen/activity_horizontal_margin"
      android:paddingRight="@dimen/activity_horizontal_margin"
      android:paddingTop="@dimen/activity_vertical_margin"
      tools:context="com.example.app2.MainActivity" &gt;
  
      &lt;TextView
          android:id="@+id/textView1"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="@string/req_input" /&gt;
  
      &lt;EditText
          android:id="@+id/editText1"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_below="@+id/textView1"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="39dp"
          android:ems="10"
          android:inputType="number" &gt;
  
          &lt;requestFocus /&gt;
      &lt;/EditText&gt;
  
      &lt;Button
          android:id="@+id/button1"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_below="@+id/editText1"
          android:layout_centerHorizontal="true"
          android:layout_marginTop="20dp"
          android:text="@strings/button_name"
          /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>This is my strings.xml:</p>
  
  <pre><code>    &lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;resources&gt;
  
      &lt;string name="app_name"&gt;App2&lt;/string&gt;
      &lt;string name="hello_world"&gt;Hello world!&lt;/string&gt;
      &lt;string name="action_settings"&gt;Settings&lt;/string&gt;
      &lt;string name="req_input"&gt;Please input the number&lt;/string&gt;
      &lt;string name="button_name"&gt;Squared&lt;/string&gt;
  
  &lt;/resources&gt;
  </code></pre>
  
  <p>strings.xml is located in values directory, which is inside res directory. I tried changing <code>android:text="@strings/button_name"</code> to <code>android:text="@+strings/button_name"</code> but instead of button text saying "Squared" it says "false". All other references to strings.xml are working fine. I'm new to Android programming so please explain as simple as possible.</p>