Switch statement 與 expression

Java 12之前

String day = "Mon";
String fullDayName = "";

switch(day){
  case "Mon": 
    fullDayName = "Monday";
    break;
  case "Tue"  :
    fullDayName = "Tuesday";
    break;
  default:
    fullDayName = "Nah";
}

Java 12之後

String day = "Mon";
String fullDayName = "";

switch(day){
  case "Mon" -> fullDayName = "Monday";
  case "Tue" -> fullDayName = "Tuesday";
  default -> fullDayName = "Nah";
}

也可以直接回傳結果給指定的參數

String day = "Mon";
String fullDayName = "";

fullDayName = switch(day){
  case "Mon" -> "Monday";
  case "Tue" -> "Tuesday";
  default -> "Nah";
}; // 注意，因為此時是expression，因此最後要加上分號

也可以使用yield關鍵字的寫法 (不想使用arrow表示式的話，應該是沒這麼堅持吧哈哈)

String day = "Mon";
String fullDayName = "";

fullDayName = switch(day){
  case "Mon" : yield "Monday";
  case "Tue" : yield "Tuesday";
  default : yield "Nah";
}; // 注意，因為此時是expression，因此最後要加上分號