Question

If I use an example for this question, it is very simple to understand:

ArrayList<String> array;
String str = toString(array);

String toString(ArrayList<String> array) {
    StringBuilder sb = new StringBuilder();
    for( String string : array ) {
        sb.append(string);
    }
    return sb.toString();
}

The question is:
How to get str‘s length efficiently without converting the array to string explicitly?

Answer 1

int length = 0;
for(String str : array){
  length += str.length();
}