Kotlin常用文法

JAvaのswitch

int test=1;
switch(test){
    case 1:
      break;
   default:
      break;
}

kotlinはjavaのswitchの代わりにwhenを使用しますが、switchよりずっと強いです.

when(test){
 var test:Int =0
        when(test){
            is Int,0 -> Log.e("tag","test is int and test=0")
            1-> "test=1"
            
            else -> Log.e("tag","test is nothing")
        }
}
//            
val x:String=""
val isString = when(x){
      is String -> x is String
      else -> false
 }

forサイクル

java:
for(int i=0;i<10;i++){
}

kotlin:
 for (i in 0..4){
}
var list = listOf("1","2","3")
 //    
 for (i in list){
//      list  item  
    i.length
}
list.forEach { 
    it.length
}