kotlin函数的举例

fun theAnswer() = 42

实际上等于

fun theAnswer ():Int{
return 42;
}

类似java的switch逻辑分支函数

fun transform(color: String): Int = when (color) {
    "Red" -> 0
    "Green" -> 1
    "Blue" -> 2
    else -> throw IllegalArgumentException("Invalid color param value")
}

等于

fun transform(color: String): Int {
return  when (color) {
    "Red" -> 0
    "Green" -> 1
    "Blue" -> 2
    else -> throw IllegalArgumentException("Invalid color param value")
}

如果用java表达 那么是

public int transform(String color){
  switch(color){
  case "Red"
  return 0;
  case "Green";
  return 1;
  case "Blue":
  return 2;
  default:
  throw new IllegalArgumentException("Invalid color param value");
}
}