title: Android Studio Cannot resolve symbol StringRequest, POST, or Response
body: <p>I am writing a java class on android studio to connect with a mysql database, but i keep receiving "cannot resolve symbol" error. No idea why. Any Help.
  Here is a part of the program:</p>
  
  <pre><code>import java.lang.reflect.Method;
  import java.net.ResponseCache;
  import com.android.volley.RequestQueue;
  import com.android.volley.Response;
  import com.android.volley.VolleyError;
  import com.android.volley.toolbox.StringRequest;
  import com.android.volley.toolbox.Volley;
  import java.util.HashMap;
  import java.util.Map;
  
  public class RegisterRequest extends StringRequest {
      private static final String REGISTER_REQUEST_URL = "****/Register.php";
      private Map&lt;String, String&gt; params;
      public RegisterRequest(String username, String password, String email, Response.Listener&lt;String&gt; listner){
          super(Method.POST, REGISTER_REQUEST_URL, listner, null);
          params = new HashMap&lt;&gt;();
          params.put("username",username);
          params.put("password",password);
          params.put("email",email);
  }
      @Override
      public Map&lt;String, String&gt; getParams() {
          return params;
   }
   }
  </code></pre>
  
  <p>I receiving error "Cannot resolve symbol" for: StringRequest, Response, POST
  Also error "Method does not override Method from it superclass" for: @Override</p>
  
  <p>Note: all volley imports are marked as unused.</p>
  
  <p>Any Help ?!!</p>