使用数组存储来自用户输入的多个变量

Question

I am relatively new to Java and would like to know how to store variables separately from a single line of user input.

At the minute the user is prompted to enter football results in the following format

home_name : away_name : home_score : away_score

and I am using a while loop to continue to ask user for input until they enter "stop"

(while (input != "stop))

Once the loop is broken I would like my program to output a variety of data such as total games played, but I'm struggling to store the home_name , away_name etc.. especially if the user wishes to enter multiple lines of results.

Answer 1

Two mainstream ways to store a "record" are:

• Maps
• Data objects

A map is more generic:

Map<String,String> match = new HashMap<>();
match.put("home_name", "Alvechurch Villa");
match.put("away_name", "Leamington");
match.put("home_score", "0");
match.put("away_score", "6");

You can add a map to a list:

List<Map<String,String>> matches = new ArrayList<>();
matches.add(list);

... and retrieve them:

Map<String,String> match = matches.get(0);
System.out.println(match.get("away_score"));

---

A data object is more tuned to your data format, but you have to write the class yourself.

public class Match {
    public String homeName;
    public String awayName;
    public int homeScore;
    public int awayScore;
}

Now you can use this class:

 Match match = new Match();
 match.homeName = "Studley";
 // etc.

You can add and retrieve these from lists too:

 List<Match> matches = new ArrayList<>();
 matches.add(match);
 Match aMatch = matches.get(0);

This is simple, but it's considered bad practice to have public fields like this - it's better to get at them via methods. For brevity, here's a data class with only one field:

 public class Player {
     private String name;
     public Player(String name) {
         this.name = name;
     }

     public String name() {
         return name;
     }
 }

 Player neilStacey = new Player("Neil Stacey");

You can use the same technique with all the fields in Match .

(A common style is to name a method like this getName() , and also to have a setName() . I have used a different style and made the object immutable , in an effort to set a good example!)

---

One advantage of the data object is that it has different types for different fields: homeName is a String, homeScore is an integer. All the fields in the Map are Strings. You can get around this by using Map<String,Object> but then as a consumer you have to cast to the right type when you read.

 String homeName = (String) match.get("home_name");

Data objects allow the compiler to do a lot of compile-time checking that helps you know your code is correct. If you use a map, you won't find out until runtime.

Answer 2

Prompt the user separately for each input.

System.out.println("home_name: ");
String hN = scan.next();
System.out.println("away_name: ");
String aN = scan.next();
System.out.println("home_score: ");
String hS = scan.next();
System.out.println("away_score: ");
String aS = scan.next();