Java switch/case 与 if 问题

Question

我一直在尝试使用java类来模拟Stack。这是我的类构造函数:

        public Stack(Class<?> type){

        if(type==String.class){

                //...

            }

            switch(type){

                    case (String.class):
                            //...
                    break;
                    case (Integer.class):
                            //...
                    break;

                    case (Double.class):
                            //...
                    break;

                    case (Byte.class):
                            //...
                    break;

                    default:
                    break;

            }

            this.counter = -1;

        }

但令我困惑的是，if block 工作正常。但对于 switch/case block ，它无法编译。

错误提示

incompatible types
                switch(type){
                       ^
  required: int
  found:    Class

还有

error: constant expression required
case (String.class):

这对 switch block 中的所有情况重复。

请指出这里是否缺少任何内容。

Answer 1

Java switch/case 仅适用于原语(byte、short、char 和 int)、枚举(来自 java 5)和字符串(来自java 7) 仅数据类型。查看oracle教程here

Unlike if-then and if-then-else statements, the switch statement can have a number of possible execution paths. A switch works with the byte, short, char, and int primitive data types. It also works with enumerated types (discussed in Enum Types), the String class, and a few special classes that wrap certain primitive types: Character, Byte, Short, and Integer (discussed in Numbers and Strings).

您可以像下面这样使用

switch(type.getName()){

  case ("java.lang.String"):
         //...
         break;
  ...
}