Question

How to replace two characters with one character in a char array? Let me explain a bit more. I have a char array of length n . In this char array i want to replace two characters with one character in a specified index i. In this process the array length is going to decrease by 1.
The idea which i came to my mind is, first create a new char array of length n-1 then copy all elements from index 0 to index i (i excluding) then insert desired character at index i then copy elements from index i+2 (i including) to the index n-1. But this process require two times for loop. Is there any better approach which can do the same in efficient manner.

Answer 1

Or a more efficient way of doing this is to use a StringBuilder which is a wrapper for char[] and let it do it for you.

char[] chars = "Hello".toCharArray();
StringBuilder sb = new StringBuilder();
sb.append(chars);
sb.replace(2, 4, "L");
System.out.println(sb);

prints

HeLo

You can look at the code for replace to see how it does it.