Extract value of the key from a map basis on a priority?

Question

I have a map of String and String. I want to extract key value and assign it to another String variable but in a priority order.

• If abc key is present, then assign value of abc to clientId variable and we are done.
• Buf if abc key is not present, then look for this key pqr and assign value of pqr to clientId variable and we are done.
• But if pqr key is also not present, then look for this key def and assign value of def to clientId variable and we are done.
• But if none of those keys are present, then value of clientId will be null.

Below is the code:

Map<String, String> holderMap = populateHolderMap<>();
String clientId = null;

if (!holderMap.isEmpty()) {
  clientId = holderMap.get("abc");
  if (Strings.isNullOrEmpty(clientId)) {
    clientId = holderMap.get("pqr");
    if (Strings.isNullOrEmpty(clientId)) {
      clientId = holderMap.get("def");
    }
  }
}

Is there any better way to write this thing? Or may be one liner using ternary operator?

There is a possibility that all three keys can be present or two keys can be present and I always have to stick to my order only. If abc key is present, then we will use that no matter whether other keys are presents or not.

Answer 1

Please go for code readability over lesser lines of code. what you have is fine.

Using ternary operator: The syntax is condition ? if_condition_true : if_condition_false;

if (!holderMap.isEmpty()) {
  clientId = holderMap.get("abc") == null ? 
             holderMap.get("pqr") == null ? 
             holderMap.get("def") == null ? 
             null : holderMap.get("def") : holderMap.get("pqr") : holderMap.get("abc");
}

Using if and else if

if (!holderMap.isEmpty()) {
    if( holderMap.get("abc") != null ) {
       clientId = holderMap.get("abc");
    } else if ( holderMap.get("pqr") != null ) {
       clientId = holderMap.get("pqr");
    } else if (holderMap.get("def") != null ) {
       clientId = holderMap.get("def");
    }
}