if you go to line 111 you'll see that the inside of a String is a char[] already More on reddit.com

Please ensure that: Your code is properly formatted as code block - see the sidebar (About on mobile) for instructions You include any and all error messages in full You ask clear questions You demonstrate effort in solving your question/problem - plain posting your assignments is forbidden (and such posts will be removed) as is asking for or giving solutions. Trying to solve problems on your own is a very important skill. Also, see Learn to help yourself in the sidebar If any of the above points is not met, your post can and will be removed without further warning. Code is to be formatted as code block (old reddit: empty line before the code, each code line indented by 4 spaces, new reddit: https://i.imgur.com/EJ7tqek.png ) or linked via an external code hoster, like pastebin.com, github gist, github, bitbucket, gitlab, etc. Please, do not use triple backticks (```) as they will only render properly on new reddit, not on old reddit. Code blocks look like this: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } } You do not need to repost unless your post has been removed by a moderator. Just use the edit function of reddit to make sure your post complies with the above. If your post has remained in violation of these rules for a prolonged period of time (at least an hour), a moderator may remove it at their discretion. In this case, they will comment with an explanation on why it has been removed, and you will be required to resubmit the entire post following the proper procedures. To potential helpers Please, do not help if any of the above points are not met, rather report the post. We are trying to improve the quality of posts here. In helping people who can't be bothered to comply with the above points, you are doing the community a disservice. I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns. More on reddit.com

char and all primitive types (int, boolean, etc.) are not objects, and thus do not have methods attached to them. If you want to compare the values of primitive types, just use double equals (==). The exception to this is a concept called "autoboxing" and "unboxing", which include the object forms of primitives (Character, Integer, Boolean, etc.), in which you can call methods such as equals(), toString(), and so forth. Unless you really have to, like with specifying generic types or supporting null, you'll use a primitive type instead of its boxed form. Here's some more reading if you like. More on reddit.com

You have the overall length of the string. You have the position of the decimal point. This is all you need. A little bit of mathematics will do the rest. Think about it: 123.4567 The overall length is 8 characters. The position of the decimal point is 3 (positions are 0-based) - it is the 4th character in the string. How many characters are before the decimal point? How many characters are after? (the length and the position of the decimal point are all you need to calculate the characters) Edit: if you are not allowed to use .indexOf, you could loop over the whole string, character by character (.charAt) and compare and count. If you reach the decimal point, you have the number of digits before the decimal point, and then either keep looping and count again (with the counter reset before restarting the count) to get the number of digits after, or, you calculate (again with the length). More on reddit.com