The grid looked at the menu and said "Something with class, please"

This is a follow up on my previous question:

A grid and a menu walked into a program

• I integrated classes into the mix.

• The program now asks how big you want the grid to be.

```
import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;

class NumberGrid {
private static final int RANDOM_NUMBER = 10;
static Random rand = new Random();
public int numberColumns;
public int numberRows;
int [][] grid;
public NumberGrid (int chosenNumberRows,int chosenNumberColumns ){
numberColumns = chosenNumberColumns;
numberRows = chosenNumberRows;
grid = new int [numberRows][numberColumns];
}

private static int randomInt(int from, int to) {
return rand.nextInt(to - from + 1) + from;
}

public void amountOfSpecificNumbers() {
int[] numbers = new int[11];
for (int y = 0; y < numberRows; y++) {
for (int x = 0; x < numberColumns; x++) {
int value = grid[y][x];
numbers[value]++;
}
}
for (int i = 1; i < numbers.length; i++) {
System.out.println(" " + numbers[i] + " " + i + "s" );
}
}

public void sumOfColumns() {
int sumOfColumns[] = new int[numberColumns];
for (int x = 0; x < numberColumns; x++) {
for (int y = 0; y < numberRows; y++) {
sumOfColumns[x] += grid[y][x];
}
}
System.out.println(Arrays.toString(sumOfColumns));
}

public void sumOfRows() {
int sumOfRows[] = new int[numberRows];
for (int y = 0; y < numberRows; y++) {
for (int x = 0; x < numberColumns; x++) {
sumOfRows[y] += grid[y][x];
}
}
System.out.println(Arrays.toString(sumOfRows));
}

public void newField() {
for (int x = 0; x < numberColumns; x++) {
for (int y = 0; y < numberRows; y++) {
int randomNumber = (randomInt(1, RA

private static final int RANDOM_NUMBER = 10;

Everyone knows the true random number is 4.

Less jokingly, what's the RANDOM_NUMBER for? Consider adding comments to explain the purpose of your variables... or better yet renaming them (to RANDOM_GRIDVALUE_MAX, perhaps).

static Random rand = new Random();
public int numberColumns;
public int numberRows;
int [][] grid;

You're missing visibility modifiers on some of your variables. Is this intentional?

Additionally, rand could be final, because it's only set once and then never set again. Perhaps (hint: there are) some of the other variables could be final too.

public NumberGrid (int chosenNumberRows,int chosenNumberColumns ){

private static int randomInt(int from, int to) {

Check your IDE for consistent syntax formatting. As an example, for Eclipse:

Ctrl + Shift + F

Or, in the main menu > Source > Format

String prompt = ("Pleas enter number 1, 2, 3, 4, 5, or 6");

Typo ("Pleas" -> "Please").

public void showField() {
    for (int y = 0; y < numberRows; y++) {
        for (int x = 0; x < numberColumns; x++) {
            if (grid[y][x] < 10) {
                System.out.print(" " + grid[y][x] + " ");
            } else {
                System.out.print(grid[y][x] + " ");
            }
        }
        System.out.println();
    }
}

You're printing SPACE + cell + SPACE if it's less than 10, or cell + SPACE if it isn't.

This was rather unclear to me... until I realized it's for padding.

I recommend moving the if statement to a separate function such as printNumberSpacePadded(int number, int toLength).

class GridColumns {
    public static int readInt(Scanner scanner){
        String prompt = ("Pleas enter the number of columns you want");
        System.out.println(prompt);
        while(!scanner.hasNextInt()) {

            System.out.println("That's not a number");
            System.out.println(prompt);
            scanner.next();
        }
        return scanner.nextInt();
    }
}

class GridRows{
    public static int readInt(Scanner scanner){
        String prompt = ("Pleas enter the number of rows you want");
        System.out.println(prompt);
        while(!scanner.hasNextInt()) {

            System.out.println("That's not a number");
            System.out.println(prompt);
            scanner.next();
        }
        return scanner.nextInt();
    }
}

Hello duplication.

Meet readInt:

public static int readInt(Scanner scanner, String inputMessage, String errorMessage) {
    System.out.println(inputMessage);
    while(!scanner.hasNextInt()) {
        System.out.println(errorMessage);
        System.out.println(inputMessage);
        scanner.next();
    }
    return scanner.nextInt();
}

Stick it somewhere, maybe in a class ScannerUtils or InputHandler (the latter one, I would make responsible of all input).

But wait, it doesn't support this version:

public static int readInt(Scanner scanner){
    String prompt = ("Pleas enter number 1, 2, 3, 4, 5, or 6");
    System.out.println(prompt);
    while(!scanner.hasNext("[1-6]")) {
        System.out.println(prompt);
        scanner.next();
    }
    return scanner.nextInt();
}

For that, simply add a String validInputPattern or something like that.

I don't think you understood classes yet. Or maybe you did, but only in a functional sense.

You've got classes that contain no variables and don't have any non-static methods. Because of that, they're little more than utility boxes...

NumberGrid is good, though.

Lastly... That menu at the end, I would rewrite it to use lambda's and some other clever trickery so that I can say something like this:

addMenuItem("Show current field", () -> numberGrid.showField());

This would then add the "2" in front of it on it's own.

Perhaps it's a bad idea, but I think it's worth a try. I don't like how case 5: means numberGrid.sumOfColumns() because there's a double duplication here...

System.out.println("5. Sum all columns"); the 5 duplicates case 5:, and System.out.println("5. Sum all columns"); the "Sum all columns" duplicates numberGrid.sumOfColumns();. Now this form of duplication isn't bad, it's just that as you add lines between the menu and the actions, it becomes harder to verify that the code is actually working as intended.

StackExchange Code Review Q#78208, answer score: 25