How to make Retrofit execute methods in exact order?

Question

I have a method that calls three(foo1(), foo2(), foo3()) api method inside it and each method is dependant on another method's response. I want to call foo1() and when it get response from api then call the foo2() and so on. I am eleborating the process below : 

public class Order{ 

   private String mResponse1 = ""; 

   private String mResponse2 = "";

   private String mResponse3 = "";

 

   public boolean CreateOrder(String param1, String param2, String param3)

   {

      foo1(param1);

   

      // Wait until foo1() get response

      if(!mResponse1.IsEmpty())

      {

         //There is some line of code here then call below method. 

         foo2(param2);

      } 

   

      // Wait until foo2() get response

      if( !mResponse2.IsEmpty())

      {

         //There is some line of code here then call below method.  

         foo3(param3);

      } 

 

      //There is some line of code here .  

      return true; 

   } 

 

   private void foo1(String param1)

   {

        ----

        ----

       mResponse1 = //Set api response

   } 

 

   private void foo2(String param2)

   {

      ----

      ----

      mResponse2 = //Set api response

   }

 

   private void foo3(String param3)

   {

        ----

        ----

        mResponse3 = //Set api response

   }

}

Now how to acheive the above senario using retrofit asynchronous calling. I can't break method CreateOrder() into three.