string replace spaces

Title:
Please implement a function that replaces each space in the string s with "%20".
Example 1:
Input: s = “We are happy.”
Output: “We%20are%20happy.”
Analysis:
Because String typeImmutable, so StringBuilder is needed to recreate a String back.

Code:

public class ReplaceSpace {public String replaceSpace(String s) {StringBuilder stringBuilder = new StringBuilder();for (int i = 0; i <s.length(); i++) {if (s.charAt(i) == ' '){stringBuilder.append("%20");}else {stringBuilder.append(s.charAt(i));}}return stringBuilder.toString();}}