Array being continuously filled inside of a switch-case unintentionally

I am currently having trouble with something I was working on recently. To keep it short and simple, I wanted my program to function as follows:

1. User inputs a number, and that number is checked to see if it's a valid option. If it's not a valid option, an error message appears and makes the main menu appear again.

2. If a valid option is chosen, a switch case takes in the chosen option and runs the code that's inside of each case statement.

3. Once the code is done running in the switch-case portion, it would loop back up to the top and re-display the main menu, and process 1-3 would continue to run until the user selects option 4 to quit the program.

The problem that I've seem to run into is that when I go into case 1, it likes to loop through a certain piece of code that's not meant to be looped through and continues to add a Triangle object to the array, which is this piece here:

if((side1 == 0 || side2 == 0 || side3 == 0)) 
{
		// Problem with do-while loop begins here
		triangleArray[trianglesAdded] = new Triangle();
		System.out.println("Default triangle created");
		trianglesAdded += 1;
}

where triangleArray is an array of Triangle objects which has a size of 100, trianglesAdded keeps track of how many triangles are actually added to the array, as well as be a variable for the index of that array. Since it keeps adding Triangle objects to this array, I get an error since the array can't hold any more Triangle objects once it's hit its limit, meaning that I also cannot loop back up to the main menu.

So my question is: how can I make it to where it can stop looping through this portion (since it's only supposed to occur once and only add one Triangle object to the array at a time) and also make it to where it can come full circle and display the main menu once again after running through?

Full code is below:

do 
	{
		while(validMenuOption == false) 
		{
			System.out.println("1. Enter data for a new triangle.");
			System.out.println("2. Print all triangles sorted by area, smallest to largest.");
			System.out.println("3. Print only triangles with a specific color.");
			System.out.println("4. Exit the program.");
			System.out.print("\nPlease enter in a number to select an option: ");
			menuOption = sc.nextInt();
			
			if(menuOption >= 1 && menuOption <= 4) 
			{
				validMenuOption = true;
			}
			
			else 
			{
				System.out.println("Invalid menu choice. Please try again.\n");
				validMenuOption = false;
			}
			
			if(menuOption == 1 && trianglesAdded == triangleArray.length - 1)
			{
				System.out.println("The triangle array has hit the max. You are unable to add more triangles.");
				validMenuOption = false;
			}
		}
		
		switch(menuOption) 
		{
			case 1:
				... 
				
				// If one, two, or all of the side lengths given are zero and the color of the triangle is 1, creates a default triangle
				// with the sides being 1 and the color being 1
				if((side1 == 0 || side2 == 0 || side3 == 0)) 
				{
					// Problem begins here
					triangleArray[trianglesAdded] = new Triangle();
					System.out.println("Default triangle created");
					trianglesAdded += 1;
				}
				
				// If side lengths greater than zero were given, creates a triangle with the side lengths and color given
				else 
				{
					triangleArray[trianglesAdded] = new Triangle(side1, side2, side3, color);
					System.out.println("Triangle created with specified size and color");
				}
				
				break;
				
			case 2:
				...
				break;
				
			case 3:
				...
				break;
				
			case 4:
                ...
				break;
				
			default:
				...
				break;
		}
	} while(true);

Well, you have a bug. So you do what everybody does when you hit a bug: You calculate what your program is supposed to do, line-by-line, in your head. Then you compare it to what the computer tells you it thinks your code means. Where your brain and your computer disagree, you found a bug.

1. Your program says that 'validMenuOption' is false.
2. I enter '1'.
3. validMenuOption is set to true, and we loop the 'input while block'.
4. vMO is now true, so the while loop is ended, we continue.
5. The switch runs, and we do the 'add a triangle' part.
6. the outer loop loops.
7. validMenuOption is still true.
8. so.. that whole 'get some input' while loop runs zero times.

Presumably you either want to reset validMenuOption first, or you want that to be a do {} while (); loop.

I would remove validMenuOption variable completely and move it to separate function, something like this:

public int getMenuOption() {
        Scanner sc = new Scanner(System.in);
        int menuOption = 0;

        System.out.println("1. Enter data for a new triangle.");
        System.out.println("2. Print all triangles sorted by area, smallest to largest.");
        System.out.println("3. Print only triangles with a specific color.");
        System.out.println("4. Exit the program.");
        System.out.print("\nPlease enter in a number to select an option: ");
        
        menuOption = sc.nextInt();

        if(menuOption < 1 || menuOption > 4) {
            return 0;
        } else {
            return menuOption;
        }
    }

See how I return 0 when option is out of range and otherwise I return menuOption.

Now in your main or wherever you run switch statement do something like this:

        boolean run = true;
        int[] triangleArray = new int[100];
        int trianglesAdded = 0;

        while (run) {
            menuOption = getMenuOption();
            switch(menuOption) {
                case 0:
                    System.out.println("Invalid menu choice. Please try again.\n");
                    break;
                case 1:
                    if(trianglesAdded == triangleArray.length - 1) {
                        System.out.println("The triangle array has hit the max. You are unable to add more triangles.");
                        run = false;
                    } else {
                        triangleArray[trianglesAdded] = 1; // or whatevery number or object you want
                        System.out.println("Default triangle created");
                        trianglesAdded += 1;
                    }
                    break;
                default:
                    break;
            }
        }

For the sake of simplicity I have made triangleArray to be an int array.
I also added a boolean variable run which runs while it is set to true and upon entering while it gets menuOption value from getMenuOption() function.

Now if it gets 0 it prints that menu option is false breaks and goes back to beginning of the loop then to getMenuOption() again. If you enter 1 it enters case 1.

The problem that you mentioned:

> I get an error since the array can't hold any more Triangle objects once it's hit its limit

Is solved by adding condition that checks length before adding to it like I did.

To exit it you would add another case which will set run to false:

case 4:
     run = false;

etc.

Here is repl for you to test it right away. I have changed the size of array to 2 so you can see the it stops when you reach the limit.

you may try the following code

while(true){
System.out.println("1. Enter data for a new triangle.");
System.out.println("2. Print all triangles sorted by area, smallest to largest.");
System.out.println("3. Print only triangles with a specific color.");
System.out.println("4. Exit the program.");
System.out.print("\nPlease enter in a number to select an option: ");
menuOption = sc.nextInt();
switch(menuOption){
case 1:
if(trianglesAdded == triangleArray.length - 1)
{
System.out.println("The triangle array has hit the max. You are unable to add more triangles.");
return;
} 
// If one, two, or all of the side lengths given are zero and the color of the triangle is 1, creates a default triangle
// with the sides being 1 and the color being 1
if((side1 == 0 || side2 == 0 || side3 == 0)) 
{
// Problem begins here
triangleArray[trianglesAdded] = new Triangle();
System.out.println("Default triangle created");
trianglesAdded += 1;
}
// If side lengths greater than zero were given, creates a triangle with the side lengths and color given
else 
{
triangleArray[trianglesAdded] = new Triangle(side1, side2, side3, color);
System.out.println("Triangle created with specified size and color");
}
break;
case 2:
...
break;
case 3:
...
break;
case 4:
...
break;
default:
System.out.println("Invalid menu choice. Please try again.\n");
break;
}
}