How to use DecimalFormat

I'm a new programming student...this is an assignment so I really need guidance or suggestions on how to make it work correctly.

I have the below code that provides conversion for a selected currency. I need to format the results with two decimal places. I think the DecimalFormat class is need somehow but I am not sure exactly where to insert the class. I tried inserting within the switch statements but keep getting an unreachable statement error (really not sure what that means).

import java.io.*;                  // required for BufferedReader


//gives my Java program the name Currency_wj
class Currency_wj {
      
      //the main part of the program begins here      
      public static void main(String[] arguments) throws Exception {
      
      //"throws Exception",
      //throws Exception needed when reading
      //from keyboard. Says you will take
      //responsibility for errors.
      

      //reads selection number from menu entered by user
      BufferedReader      br = new BufferedReader(
      new InputStreamReader(System.in));
      
      //reads amount entered by user
      BufferedReader money = new BufferedReader(
      new InputStreamReader(System.in));
                                    
      double ArgentinaCurrency = 2.95;  //declare and initialize  
      double CanadaCurrency = 1.32;       //declare and initialize
      double calculate = 0.00;            
      String cname1 = "Argentina Peso";  //declare and initialize string
      String cname2 = "\nCanada Dollar"; //declare and initialize string
      String cnames = cname1.concat(cname2); //concatenate two Strings
      String intro = "Welcome to the "; //declare and initialize String
      String name = "Currency Exchange Program!"; //declare and initialize String
      String title = intro.concat(name); //concatenate two Strings
      double dollar; //delcare and initialize
            
      //display combination of concatenated string             
      System.out.println(title + "\n\nThe currency exchange program shows\n"+
      "the exchange rate of $1 American dollar\n" +
      "for the following currencies:\n\n" + cnames);      
            
      // prints a blank line
      System.out.println();
            
      //display current currency rates
      System.out.println(cname1 + " = " + ArgentinaCurrency + cname2 + " = " +  CanadaCurrency);
            
      //prints a blank line
      System.out.println();
            
            
      char keep_going = ' ';          // initialize, set initial value
      String inString;            //declare
      char MenuChoice;            //delcare
      dollar = 0.00;            //declare and set initial value
      double amount = 0.0;      //delcare and set initial value
      String data = "oo";            //
      

      while (keep_going != 'q')       // will continue loop until condition met
      {
            //displays to screen statement in quotes
            System.out.println("\nSelect a currency to convert:\n");
            System.out.println("      1. Argentina Pesos");
            System.out.println("      2. Canada Dollars");
            System.out.println("      3. Exit.");    
                                       

            // Send all output to the monitor and make the
            // cursor visible before the user begins typing.
            System.out.flush();
            
            // "readline()" returns a String which is
            // assigned to a String variable, inString
            inString = br.readLine();
            
            MenuChoice = inString.charAt(0);
            // get first char of String
                                       
            
            //switch case statement, displays data to screen depending on user selection
            switch(MenuChoice)
            {
                  case '1':           
                  //displays data in quotes to screen      
                  System.out.println("You want to convert Argentina Pesos");
                        
                  //displays data in quotes to screen
                  System.out.print("Enter dollar amount to convert: ");
                        
                  //displays data and displays cursor
                  System.out.flush();
                        
                  //stores amount entered by user
                  data = money.readLine();
                        
                  //converts string to double
                  amount = Double.parseDouble(data);
                         
                  //displays amount entered, currency name, calculates conversion and  displays results
      System.out.println(amount + " Argentina Pesos equal " + amount*ArgentinaCurrency + " American Dollars");
      break;
                                    
                            case '2':
                  //displays data in quotes to screen
                  System.out.println("You want to convert Canada Dollars");
                        
                  //displays data in quotes to screen
                  System.out.print("Enter dollar amount to convert: ");
                        
                  //displays data and displays cursor
                  System.out.flush();
                        
                  //stores amount entered by user
                  data = money.readLine();
                        
                  //converts string to double
                  amount = Double.parseDouble(data);
                        
                  //displays amount entered, currency name, calculates conversion and displays results
                  System.out.println(amount + " Canada Dollars equal " + amount*CanadaCurrency + " American Dollars");
                  break;                  
                        
                  case '3':
                  //condition met -- program exits
                  keep_going = 'q';
                  break;
                  
                  default:
                  //displays data to screen when invalid entry entered
                  System.out.println("You entered an invalid number, please enter 1-3");                  break;
                        
            } // end switch
      }      // end while


      //displays data in quotes to screen      
      System.out.print("\nThank you for using the Currency Exchange Program\n");
      
      
            
            }//end main
      }//end class




Any suggestions would be greatly appreciated.