kotlin - Is it considered bad convention when in iterating through two maps, I don't check if key exists in one of them?

Question

I have two maps, let's call them oneMap and twoMap.

I am iterating through all the keys in oneMap, and if the key exists in twoMap I do something like

fun exampleFunc(oneMap: Map<String, Any>, twoMap: Map<String, Any>) {
   for((oneMapKey, oneMapVal) in oneMap) {
      if (twoMap.containsKey(oneMapKey)) {
         val twoMapVal = twoMap[oneMapKey]
         if (twoMapVal == oneMapVal) {
            //do more stuff
         }  
         //do more stuff, I have more if statements
      }      
   }
}

To avoid having more nested if statements, I was wondering if instead I could get rid of the

if (twoMap.containsKey(oneMapKey)) check. if twoMap doesn't contain the oneMapKey, we get a null object, and my code still works fine. I was wondering if this is considered bad convention though

fun exampleFunc(oneMap: Map<String, Any>, twoMap: Map<String, Any>) {
   for((oneMapKey, oneMapVal) in oneMap) {
      
      val twoMapVal = twoMap[oneMapKey]
      if (twoMapVal == oneMapVal) {
         //do more stuff
      }  
      //do more stuff, I have more if statements
        
   }
}

question from:https://stackoverflow.com/questions/65602476/is-it-considered-bad-convention-when-in-iterating-through-two-maps-i-dont-chec

Answer 1

It depends. Do you wanna execute the "more stuff" or not?

If you do not wanna execute it you should keep the if condition. Though, if you are concerned about indentation (and deep if hierarchies) you can consider breaking out of the loop:

for((oneMapKey, oneMapVal) in oneMap) {
  if (!twoMap.contains(oneMapKey)) continue // continue with next iteration

  // do more stuff
}

If your map does not contain null values you can also get the value and check if the result was null (which means the key was not present in the map):

for((oneMapKey, oneMapVal) in oneMap) {
  val twoMapVal: Any = twoMap[oneMapKey] ?: continue // continue with next iteration

  // do more stuff
}

So its always good practice the remove useless code and (in my opinion) to have less if-hierarchies, as you can easily loose focus when you have lots of nested conditions.