java - Need some help to understand what is done in the second line of code? -

 public <t> void addtorequestqueue(request<t> req, string tag) {     req.settag(textutils.isempty(tag) ? tag : tag);     getrequestqueue().add(req); } 

what done in second line? can't understand (tag) ?tag :tag.

here full code

{ import android.app.application; import android.text.textutils;  import com.android.volley.request; import com.android.volley.requestqueue; import com.android.volley.toolbox.volley;  public class appcontroller extends application {      public static final string tag = appcontroller.class.getsimplename();      private requestqueue mrequestqueue;      private static appcontroller minstance;      @override     public void oncreate() {         super.oncreate();         minstance = this;     }      public static synchronized appcontroller getinstance() {         return minstance;     }      public requestqueue getrequestqueue() {         if (mrequestqueue == null) {             mrequestqueue = volley.newrequestqueue(getapplicationcontext());         }          return mrequestqueue;     }      public <t> void addtorequestqueue(request<t> req, string tag) {         req.settag(textutils.isempty(tag) ? tag : tag);         getrequestqueue().add(req);     }      public <t> void addtorequestqueue(request<t> req) {         req.settag(tag);         getrequestqueue().add(req);     }      public void cancelpendingrequests(object tag) {         if (mrequestqueue != null) {             mrequestqueue.cancelall(tag);         }     } } 

here full code tell me , please explain if can done in method second line

translation of second line

public static final string tag = appcontroller.class.getsimplename();  public <t> void addtorequestqueue(request<t> req, string tag) {     req.settag("is tag empty?" yes, use `tag` : no, use `tag`);     getrequestqueue().add(req); }  

in words:

if(tag.isempty()){   res.settag(tag)  } else {   res.settag(tag)  }