question:

Defanging an IP Address

Given a valid (IPv4) IP address, return a defanged version of that IP address.

A defanged IP address replaces every period "." with "[.]".

Example 1:

Input: address = "1.1.1.1"
Output: "1[.]1[.]1[.]1"
Example 2:

Input: address = "255.100.50.0"
Output: "255[.]100[.]50[.]0"

Constraints:

The given address is a valid IPv4 address.

Ideas:

1.use StringBuffer,

 public String defangIPaddr(String address) {
  
         StringBuffer a =new StringBuffer();
        char[] chars = address.toCharArray();
        for (int i = 0; i < address.length(); i++) {
            if(chars[i]=='.'){
                a.append("[.]");
            }else{
                a.append(chars[i]);
            }
        }
        return  a.toString();        
   }

2.use replace

public class test {
    public String defangIPaddr(String address) {
        return address.replace(".", "[.]");
    }