Java – how do I traverse an array and check for duplicates?

I'm creating a program that allows you to store 10 items in an array What I can't let the program do is that if one of the input items already exists in the array, an error will occur

So, for example, if the array looks like [banana, potato, 3,4, yes,......] and I enter banana again, it should say "the item has been stored" and ask me to re-enter the value My current code is:

public static void main(String[] args) {
        Scanner keyboard = new Scanner(system.in);
        int stringNumber = 0;
        String[] stringArray = new String[10];

        for (int i = 0; i <= stringArray.length; i++) {

            out.println("\nEnter a string");
            String input = keyboard.next();
            stringArray[stringNumber] = input;
            out.println("\"" + stringArray[stringNumber] + "\"" + " has been stored.");

            PrintArray(stringArray);
            stringNumber++;

Solution

You can use nested loops to iterate through the array to see if new input exists It is better to do this in a function In addition, when performing this operation, you need to ensure that you are not in the first element, otherwise you will get a null pointer exception

for (int i = 0; i <= stringArray.length; i++) {

        boolean isInArray = false;

        System.out.println("\nEnter a string");
        String input = keyboard.next();

        if (i > 0) {

            for (int j = 0; j < stringArray.length; j++) {
                if (stringArray[j].equalsIgnoreCase(input)) {
                    isInArray = true;
                    break;
                }
            }
        }
        if (!isInArray) {
            stringArray[stringNumber] = input;
        } else {
            System.out.println("\"" + stringArray[stringNumber-1] + "\""
                    + " has been stored.");
        }
        PrintArray(stringArray);
        stringNumber++;
    }