LinkedHashMap keys to ArrayList

Question

What is the easiest way to add the keys of a LinkedHashMap to an ArrayList? I would like to increase performance by removing loops. Is there a more efficient way?

for(String key : map.keySet()){
 array.add(key);
}

• Ricardo: Why not array.addAll()?
• Ernir Erlingsson: FYI: You are not necessarily improving performance with shorter code, especially when it comes to for loops, the compiler now a days is very good at optimizing those for you.
• stefana: @ErnirErlingsson If for example the method addAll contains the same loop but has null checks, it is slower??
• Ernir Erlingsson: addAll() will be faster or the same, but should not be slower although you never know what the compiler does to your code without directly checking for it. My point is just that shorter code does not always mean faster code as I felt you were implying with your question.

Answer 1

List array = new ArrayList(map.keySet());