title: how to make animation for popup window in android
body: <p>I hava a popup window in my application, its appears when some button clicked
  I want to set fade in animation to this window,
  I put the xml file in "res/anim" folder and set the animation style for the popup window but the animation does not work? 
  here is my codes:</p>
  
  <p>myanim.xml...</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;set xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;alpha android:fromAlpha="0.0"
          android:toAlpha="1.0" 
          android:interpolator="@android:anim/accelerate_interpolator" 
          android:duration="4000"
          android:repeatCount="1"/&gt;
  &lt;/set&gt;
  </code></pre>
  
  <p>===============================================</p>
  
  <p>Create the popup window</p>
  
  <pre><code>private PopupWindow showOptions(Context mcon){
      try{ 
          LayoutInflater inflater = (LayoutInflater) mcon.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
          View layout = inflater.inflate(R.layout.options_layout,null);
          layout.setAnimation(AnimationUtils.loadAnimation(this, R.anim.myanim));
          PopupWindow optionspu = new PopupWindow(layout, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
  
          optionspu.setFocusable(true);
          optionspu.showAtLocation(layout, Gravity.TOP, 0, 0);
          optionspu.update(0, 0, LayoutParams.WRAP_CONTENT, (int)(hei/5));
          optionspu.setAnimationStyle(R.anim.myanim);
          return optionspu;
      }
      catch (Exception e){e.printStackTrace();
      return null;}
  }
  </code></pre>
  
  <p>=================================================
  onClick method... (optionsPopup is global variable of type PopupWindow)</p>
  
  <pre><code> @Override
  public void onClick(View v) {
                 switch (v.getId()) { 
          case R.id.options:
                  optionsPopup=showOptions(this);
              break;  
  }
  </code></pre>