??IDE:Android Studio
??無法使用Recyclerview，android.support.v7.widget中并沒有。
??解決辦法如下：(https://stackoverflow.com/questions/24441107/recyclerview-is-missing)
You have to update the android repository, the support library and you have to use this dependency:

compile 'com.android.support:recyclerview-v7:+'

You can refer the stackoverflow documentation for more details.
UPDATED 16/10/2015:
Using the + is not a good option because you are not able to replicate the build in the future.
You can use one of these versions. Check your sdk for updated version:

  //it requires compileSdkVersion 25
  compile 'com.android.support:recyclerview-v7:25.1.0'  
  compile 'com.android.support:recyclerview-v7:25.0.0'  

  //it requires compileSdkVersion 24
  compile 'com.android.support:recyclerview-v7:24.1.1'  
  compile 'com.android.support:recyclerview-v7:24.1.0'  

  //it requires compileSdkVersion 23
  compile 'com.android.support:recyclerview-v7:23.4.0'
  compile 'com.android.support:recyclerview-v7:23.3.0'
  compile 'com.android.support:recyclerview-v7:23.2.1'
  compile 'com.android.support:recyclerview-v7:23.2.0'
  compile 'com.android.support:recyclerview-v7:23.1.1'
  compile 'com.android.support:recyclerview-v7:23.1.0'
  compile 'com.android.support:recyclerview-v7:23.0.1'
  compile 'com.android.support:recyclerview-v7:23.0.0'

  //it requires compileSdkVersion 22
  compile 'com.android.support:recyclerview-v7:22.2.1'
  compile 'com.android.support:recyclerview-v7:22.2.0'
  compile 'com.android.support:recyclerview-v7:22.1.1'
  compile 'com.android.support:recyclerview-v7:22.1.0'
  compile 'com.android.support:recyclerview-v7:22.0.0'

  //it requires compileSdkVersion 21
  compile 'com.android.support:recyclerview-v7:21.0.3'
  compile 'com.android.support:recyclerview-v7:21.0.2'
  compile 'com.android.support:recyclerview-v7:21.0.0'