title: Cleaned project, my R.java file won't generate because of error in XML file?
body: <p>I was trying to run my project in my Genymotion emulator, but none of the new updated buttons that I added were showing when I ran my Android application. So, I made a copy of my project to run a "clean" on it because I've had problems with my R.java file not being generated after cleaning it, and I was right as the R.java file didn't generate in the copied project. I'm almost sure it's a problem in my XML file, but my XML file shows no errors. </p>
  
  <p>I also had the same error before, which I posted about here: <a href="https://stackoverflow.com/questions/21768370/r-cannot-be-resolved-to-a-variable">R cannot be resolved to a variable?</a></p>
  
  <p>The R file is not being generated so all my calls in MainActivity like <code>mBitmap = BitmapFactory.decodeResource(getResources(),R.drawable.crayon);</code> are stating "R cannot be resolved to a variable" which I know points to a problem in my XML file.</p>
  
  <p>Here is my activity_main.xml file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout 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:orientation="vertical"
     android:paddingBottom="@dimen/activity_vertical_margin"
     android:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
     android:gravity="center"
     tools:context=".MainActivity" &gt;
  
  &lt;LinearLayout
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:gravity="center_horizontal|fill_horizontal|center"
      android:orientation="horizontal" &gt;
  
      &lt;RadioGroup
          android:id="@+id/greyorcolor"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:orientation="horizontal" &gt;
  
          &lt;RadioButton
              android:id="@+id/grey"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:checked="true"
              android:text="@string/reyscale" /&gt;
  
          &lt;RadioButton
              android:id="@+id/color"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:checked="true"
              android:text="@string/color" /&gt;
      &lt;/RadioGroup&gt;
  
      &lt;RadioGroup
          android:id="@+id/smallorlarge"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:orientation="horizontal" &gt;
  
          &lt;RadioButton
              android:id="@+id/large"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:checked="true"
              android:text="@string/large" /&gt;
  
          &lt;RadioButton
              android:id="@+id/small"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:checked="true"
              android:text="@string/small" /&gt;
      &lt;/RadioGroup&gt;
  &lt;/LinearLayout&gt;
  
  &lt;edu.berkeley.cs160.opalkale.prog2.DrawingView
      android:id="@+id/drawing"
      android:layout_width="fill_parent"
      android:layout_height="0dip"
      android:layout_marginBottom="3dp"
      android:layout_marginLeft="5dp"
      android:layout_marginRight="5dp"
      android:layout_marginTop="3dp"
      android:layout_weight="1"
      android:orientation="vertical"
      android:src="@drawable/ic_launcher" /&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <hr>
  
  <p>My strings.xml file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;resources&gt;
  
     &lt;string name="app_name"&gt;Drawing&lt;/string&gt;
     &lt;string name="greyscale"&gt;Greyscale&lt;/string&gt;
     &lt;string name="color"&gt;Color&lt;/string&gt;
     &lt;string name="small"&gt;Small Brush&lt;/string&gt;
     &lt;string name="large"&gt;Large Brush&lt;/string&gt;
     &lt;string name="hello_world"&gt;Hello world!&lt;/string&gt; &lt;/resources&gt;
  </code></pre>
  
  <p>My MainActivity.java file:</p>
  
  <pre><code>package edu.berkeley.cs160.opalkale.prog2;
  
  import android.os.Bundle;
  import android.app.Activity;
  import android.view.Menu;
  import android.graphics.Bitmap;
  import android.graphics.BitmapFactory;
  import android.graphics.Canvas;
  
  public class MainActivity extends Activity {
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      Bitmap munBitmap = BitmapFactory.decodeResource(getResources(),
              R.drawable.crayon);
      Bitmap mBitmap = munBitmap.copy(Bitmap.Config.ARGB_8888, true);
      Canvas canvas = new Canvas(mBitmap);
  
      DrawingView drawingView = (DrawingView) findViewById(R.id.drawing);
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.main, menu);
      return true;
  }
  
  }
  </code></pre>
  
  <p>Problems window: 
  <img src="https://i.stack.imgur.com/pptGU.png" alt="enter image description here">
      enter code here</p>