string - 在 Groovy Switch-Case 语句中使用静态字符串

Question

我是一名 Java 程序员，正在涉足 Groovy。您会注意到，在我的代码中，我混合了一些 Java 特定的语法，这对于 Groovy 来说应该是没问题的。

谁能向我解释为什么 Groovy 不接受静态变量作为 CASE 参数？或者如果会的话，你能看到我在这里做错了什么吗？

public static final String HIGH_STRING = "high";
public static final String LOW_STRING  = "low";

... //other code, method signature, etc.

def val = "high";
switch (val) {

   case HIGH_STRING:
     println("string was high"); //this won't match
     break;

   case LOW_STRING:
     println("string was low");  //this won't match
     break;

   //case "high":
   //  println("string was high"); //this will match because "high" is a literal
   //  break;

   default:
     println("no match");
}

... //other code, method closeout, etc.

Answer 1

我知道这并不能回答你为什么你的代码不适合你的问题，但是如果你想要一个稍微更时髦/更好的方法来实现你的代码，你可以将你的值放入映射中，这样你就不会必须使用 switch 语句:

class ValueTests {
    public static final String HIGH_STRING = "high"
    public static final String LOW_STRING  = "low"

    @Test
    void stuff() {
        assert "string was high" == getValue("high")
        assert "string was low" == getValue("low")
        assert "no match" == getValue("higher")
    }

    def getValue(String key) {
        def valuesMap = [
            (HIGH_STRING): "string was high", 
            (LOW_STRING):"string was low"
        ]
        valuesMap.get(key) ?: "no match"
    }

}

在我看来，比开关干净一点。