Java || Array elements set to 0 after varArr[i] = varInt

I hope I can describe this adequately.

<h3>What the program does:</h3>
<p>This section of the program checks to see what items are available for purchase, displays those items and then asks the user which items they want to buy. Then it asks how many of that item they want to purchase and adds that number to an array of integers, where that arrays index corresponds to the index of item names (so the name and quantity are stored in two arrays, but are aligned by index). Once the integer has been entered into the array, the loop starts again asking for an item to purchase, until the user enters 'finish', which stops the loop. Another method uses that integer array to generate a receipt.</p>

<h3>My problem:</h3>
<p>When it comes time to enter the integer into the array, I print that array to console immediately after, and get this result.</p>

Say, the first loop adds '10' to index '1'.

element at index '0' = 0
element at index '1' = 10
element at index '2' = 0
element at index '3' = 0

Then say, the second loop adds '20' to index '3'.

element at index '0' = 0
element at index '1' = 0
element at index '2' = 0
element at index '3' = 20

My question is, why does index '1' revert to '0'?

<h3>What I expect:</h3>

<p>I expect the integers to just keep being added to the array. Using the above example, once the second loop is done, I expect the following result.</p>

element at index '0' = 0
element at index '1' = 10
element at index '2' = 0
element at index '3' = 20

<h3>The code:</h3>
Edit: Added the rest of this block to meet minimal, reproducible example.

do {
	System.out.println(saleMenu);
	String[] availArray = new String[stockName.length];
	for (int i = 0; i < stockLevel.length; i++) {
		if (stockLevel[i] > 0) {
			availArray[i] = stockName[i];
		}
	}
	for (int i = 0; i < availArray.length; i++) {
		System.out.println(availArray[i]);
	}
	System.out.println("\nType 'finish' to generate a receipt.");
	soldItems = new int[availArray.length];
	System.out.println(saleMenu2);										// Display menu.
	String input = console.nextLine().toLowerCase();					// Get input.
	if (!(input.contains("finish"))) {									// If input not "finish".
		for (int i = 0; i < availArray.length; i++) {					// Loop through availableArray
			if (availArray[i].equals(input)) {							// If stock present.
				available = true;										// Set available flag.
				index = i;												// Grab the index.
			}
		}
		if (available == false) {										// If input not available.
			System.out.print("That is not an option. Try again.\n");	// Display error.
		}
		if (available == true) {										// If input available.
			available = false;											// Reset available flag.
			System.out.println("How many would you like to purchase?");	// Display message.
			amountInput = console.nextInt();							// Get input.
			console.nextLine();											// Capture stray \n
			if (amountInput < 0) {										// Is input < 0.
				System.out.println("\nSorry, the number must be positive.");	// Display error.
			} else
				if (!(amountInput == 0)) {								// If input not 0.
					soldItems[index] += amountInput;					// Add input to array at 
																		// 'index' grabbed above.
				}
				else
					System.out.println("\nNothing added.");				// If input 0, display error.
			for (int i = 0; i < soldItems.length; i++) {								// Debugging
				System.out.println("sldItems at index '" + i + "' " + soldItems[i]);	// Debugging.
			}
		}
	} else
		finishedSale = true;
} while (finishedSale == false);
processSale(soldItems, stockLevel);
System.out.print(continueOption);
continueYN = console.nextLine().toLowerCase().charAt(0);
if (continueYN == 'y') {
	mainMenuSelect = 0;
}
break;

do {
    // [...]
    soldItems = new int[availArray.length];
    // [...]
} while (finishedSale == false)

You are resetting the array on each iteration. After each purchase, the array is wiped and newly instantiated -- containing zeroes. Move the instantiation outside the loop.

_{Btw, instead of finishedSale == false it is more idiomatic to write !finishedSale.}