Java CharAt() and deleteCharAt() performance

Question

I\'ve been wondering about the implementation of charAt function for String/StringBuilder/StringBuffer in java what is the complexity of that ? also what about the deleteCha

Answer 1

Since we all know that the string is implemented in JDK as a character array, which implements the randomAccess interface. Therefore the time complexity of charAt should be int O(1). As other arrays, the delete operation has the O(n) time complexity.