Implement a function that replaces a space in a string with "%20". For example, when the string is we are Happy. The string after substitution is we%20are%20happy.

Replace two ways to use: replace (int start,int end, String str)

Replace (char Oldchar, char Newchar)

public class Solution {
Public String replacespace (StringBuffer str) {
if (str==null) {
return null;
}
else{
StringBuffer newstr=new StringBuffer ();
for (int i=0;i<str.length (); i++) {
if (Str.charat (i) = = ")
Str.replace (i,i+1, "%20");
}
return str.tostring ();
}
}
}

Implement a function that replaces a space in a string with "%20". For example, when the string is we are Happy. The string after substitution is we%20are%20happy.