phone_number return
"01033334444" "***4444"
"027778888" "*8888"
class Solution {
public String solution(String phone_number) {
String answer = "";
int number;
number = phone_number.length();
for(int i=0; i<number-4; i++){
answer+="*";
}
answer += phone_number.substring(number-4);
return answer;
}
}