Array contains() without case sensitive lookup? [duplicate]

Answer 1

it will require you to write your own contains() method. pointers for custom contains():

1. iterate over all the elements in the list.
2. compare the parameter string with all the values in

3. to make comparison case-insensitive be sure to apply any of toLowerCase or toUpperCase on BOTH parameter and the current element.

   List list; public boolean contains(String str){

      for(int i=0;i<list.size();i++){
          if(list.elementAt(i).toLowerCase().Equals(str.toLowerCase())) return true;
      }
   return false;
   }
   

Answer 2

contains just check if an object is present in the List. So you can't do a case insensitive lookup here, because "three" is a different object than "Three".

A simple approach to solve this would be

public boolean containsCaseInsensitive(String s, List<String> l){
     for (String string : l){
        if (string.equalsIgnoreCase(s)){
            return true;
         }
     }
    return false;
  }

and then

containsCaseInsensitive("three", data);

Java 8+ version:

public boolean containsCaseInsensitive(String s, List<String> l){
        return l.stream().anyMatch(x -> x.equalsIgnoreCase(s));
    }