糟糕的 if-else 或 switch 结构的 Java 替代方案

Question

寻找现代方式来实现字符串转换以替换难看的 if-else 或 switch 结构:

if ("UK".equals(country)) 
     name = "United Kingdom";
  if ("GE".equals(country))
     name = "Germany";
  if ("FR".equals(country))
     name = "France";
  if ("IT".equals(country))
     name = "Italy";
  [...]

或

switch (country) {
      case "UK": name = "United Kingdom"; break;
      case "GE": name = "Germany" break;
      case "FR": name = "France"; break;
      case "IT": name = "Italy" break;
  [...]

Answer 1

您可能需要一个枚举。

public enum Country {
    UK("United Kingdom"),
    GE("Germany"), // sure this isn't DE?
    FR("France");
    // and so on
    private String countryName;
    private Country(String n) { countryName = n; }

    public String getCountryName() { return countryName; }
}

现在你可以

Country c = Country.valueOf(countryString); // throws exception when unknown
name = c.getCountryName();