Hello,

I'm working on some code that reads in millions of lines of data from a CSV and performs some rudimentary correlation analysis on that data. The code is working and running well how I have it implemented now BUT I am currently calling split() on every record I read in from the CSV and I'm aware that calling string splits in a loop can cause massive memory usage.

Anyone have any interesting/clever thoughts on how to achieve this without using split() to make it more efficient? I could write my own method to split the string but I'm just curious about any alternatives.

Edit: Just wanted to add that any clever ideas are appreciated but I'm more interested in being pointed in the right direction, rather than having someone solve this for me.

Hello Night Owls,

I have seen a lot of frustration over Practice Assessment Lab question 20.6 and Lab 3.26 (Section 3 practice lab of a similar or exact same nature).

Students, including myself, were struggling to solve this using only what zyBooks provides us, and that does *not* include the .split() method. So, seeing this as the only suggestion was a little annoying, and it also shows a reliance on chatGPT, which some students may want to avoid for the sake of it.

So, I am providing my solution and breakdown (with full explanation) here to give back to this community for the help it provides, and to, hopefully, ease some frustrations.

——————————————————

The lab itself asks students to write a program that accepts a full name and formats it into “lastInitial., fullFirstName middleInitial.”

So “Aye Bee Cee” formats to “C., Aye B.” and “Aye Cee” formats to “C., Aye”.

To solve this, we are going to use .substring(), .indexOf(), and .lastIndexOf() from lesson 3.16.

——————————————————

Your final code will look something like this (aka TLDR;):

import java.util.Scanner; 
public class LabProgram {
   public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
       
String fullName = scnr.nextLine();

int firstSpaceIndex = fullName.indexOf(" ");
int lastSpaceIndex = fullName.lastIndexOf(" ");

String firstName = fullName.substring(0, firstSpaceIndex);  
String middleInitial;
String lastInitial;
/* OR String lastInitial = fullName.substring(lastSpaceIndex + 1, lastSpaceIndex + 2); */

if (firstSpaceIndex != lastSpaceIndex) {
middleInitial = fullName.substring(firstSpaceIndex + 1, firstSpaceIndex + 2);
lastInitial = fullName.substring(lastSpaceIndex + 1, lastSpaceIndex + 2);
System.out.println(lastInitial + "., " + firstName + " " + middleInitial + ".");
}

else {
lastInitial = fullName.substring(firstSpaceIndex + 1, firstSpaceIndex + 2);
System.out.println(lastInitial + "., " + firstName);
}
   }
}

——————————————————

Scanner should already be established as “Scanner scnr = new Scanner(System.in);” to take in user input.

——————————————————

String fullName = scnr.nextLine();

Start by establishing getting the user input through scanner.
We declare the data type as String, provide a variable name (fullName in this case) and initialize it with user input through scanner.
~Recall that .nextLine() takes in a full singular line as it is written out by the user. (Versus .next(), which only takes in each element up to the next whitespace — you’ll see why we‘re not using this).

——————————————————

int firstSpaceIndex = fullName.indexOf(“ “);

Next, we need to establish where the whitespace is in our full string to help separate each section of the name. We do this by referencing the index in which the whitespace is to give us starting points.

So we declare the data type as int, provide a variable name (firstSpaceIndex in this case — the index number of the first space in our string) and initialize it with the method .indexOf(). We use variable fullName, since that is where the whitespace is coming from, and .indexOf() inherently locates the FIRST instance of whatever is referenced in the parentheses (in this case, a space, denoted as “ “). We will later reference this as a starting point for substrings firstName, middle name, and last name.

——————————————————

int lastSpaceIndex = fullName.lastIndexOf(” “);

Next, we establish the index of the LAST instance of a whitespace in the string fullName. The last name is located after the last whitespace as seen in Aye Bee Cee (Aye_Bee**_**Cee).

Again, we declare the data type int (since index is an integer), provide a succinct variable name, and initialize it with the .lastIndexOf() method used on the fullName variable. .lastIndexOf() does what it says, inherently locating the last instance of whatever is in the parentheses.
So if the user input were to be a full name with multiple middle names, such “Salvador Felipe Jacinto Dali”, .lastIndexOf(” “) would refer to the space just before Dali. Remember, this lab works under the assumption of 1 or 0 middle names, but this is to clarify how .lastIndexOf() works. It serves as a starting point for the input last name.

——————————————————

String firstName = fullName.substring(0, firstSpaceIndex);
String middleInitial;
String lastInitial;

Next, we make a few more necessary declarations. Firstly, our constant is the display of the full first name, so we declare it as a String, provide a variable name (firstName), and initialize it using the .substring() method because the firstName is a substring of the full String fullName. The substring firstName starts at index 0, always, because it’s -duh- the first name, and it goes up to the first whitespace in fullName (aka firstSpaceIndex).

The syntax for the substring method is “variableName.substring(x, y);“ with x being the index of the first element to be included in the result and y being the last element minus 1, meaning y is not included in the result; rather, the element before y is. **The “minus y” is inherent in the method.

The other declared variables are both Strings (even though the result is a character, we need to reference the individual character in the full string of the middle and/or last name). You may name them as you see fit, but in order to apply the substring method, it must be applied to a String data type (it cannot be applied to a char data type).

Now that we have our variables declared, we are going to use an if branch to configure and output the properly formatted result being asked of us.

——————————————————

Our if-branch will determine: if the index for firstSpaceIndex is NOT the same as lastSpaceIndex (meaning there are minimally 2 white spaces, indicating the presence of a middle name), then we determine and output the first letter of both the middle name and last name as “C., Aye B.”.

if (firstSpaceIndex != lastSpaceIndex) {
middleInitial = fullName.substring(firstSpaceIndex + 1, firstSpaceIndex + 2);

To find the first letter of the middle name, we reference the substring of the fullName string, starting at the index after the first whitespace (firstSpaceIndex + 1) and ending at firstSpaceIndex + 2, which is simply the ending point and not included in the result, making the only position to print the letter at index (firstSpaceIndex + 1).

So, with Aye Bee Cee:

Aye is from index 0 - 2. The first whitespace is at index 3. Bee is from index 4 - 6. The next/last whitespace is at index 7. Cee is from index 8 - 10.

——————————————————

Within the same if-section, we do the same with lastInitial as we did with middleInitial (using the reference point of lastSpaceIndex), then print the formatting.

lastInitial = fullName.substring(lastSpaceIndex + 1, lastSpaceIndex + 2);
System.out.println(lastInitial + “., “ + firstName + “ “ + middleInitial + “.”);
}

——————————————————

Then, we finish off with the else branch, which will cover the formatting for if no middle name exists. It is implied that the else branch executes if firstSpaceIndex == lastSpaceIndex.
So, in the name “Aye Cee”, there is one whitespace that serves as both the first (fullName.indexOf(“ “)) and last instance (fullName.lastIndexOf(“ “)) of the whitespace “ “ referenced in the parentheses.

else {
lastInitial = fullName.substring(firstSpaceIndex + 1, firstSpaceIndex + 2);
System.out.println(lastInitial + “., “ + firstName);
}

You can also use *lastInitial = fullName.substring(*lastSpaceIndex + 1, lastSpaceIndex + 2) in the else-branch, since it gives the same result.
You can also simplify your code a bit and just establish this in the declaration for lastInitial before your if-branch (keep in mind, this will only work using lastSpaceIndex, not firstSpaceIndex).

——————————————————

I hope this breaks it down in a way that makes sense for you guys.
If you find any issues with running the code, or any typos or syntax errors, let me know, and I will correct it.

Be sure to try this on your own to work out the concept of it and not just copy and paste.

If you choose to use the much simpler .split() method, more power to you.

Thanks for your time, everyone.