Does not find specific number in array

Question

I am trying to write a program that creates an array and fill it with int numbers(first method). In the end, it is supposed to see if a specific number is given in the array(second method). The problem is that the program does not run my if loops. I do not know why. The variable x is the number the program is looking for in the array and pos the position of the number in the array

public class Program {

    static int [] numbers= new int[100];
    
    public static void main(String [] args) {

        PrintWriter out = new PrintWriter(System.out);

        arrayConstruction();
        test(out);
        out.flush();
    }

    public static void arrayConstruction() {
        int x = 0;
        for (int i = 0; i < numbers.length; i++) {
            numbers[i] = x;
            x++;
        }
    }

    public static void test(PrintWriter out) {
        int x = 17;
        int pos = 0;
        if(pos != numbers.length) {
            if(numbers[pos] == x) {
                out.println("The number was found!");
                out.flush();
            }
            
            pos++;
        }
        
        else if(pos == numbers.length) {
            out.println("The number does not exist!");
            out.flush();
        }
    }
}

I think your are looking for a while loop as an "if loop" is not a thing. — kpie
– kpie, Commented Jan 19, 2022 at 22:30

Oleg Cherednik · Accepted Answer · 2022-01-19 22:42:53Z

2

You forgot to add a loop to the test method, so it checks the first array's item only. E.g. you can use while loop.

public static void test(PrintWriter out) {
    int x = 17;
    int pos = 0;

    while (true) {
        if (pos != numbers.length) {
            if (numbers[pos] == x) {
                out.println("The number was found!");
                return;
            }

            pos++;
        } else if (pos == numbers.length) {
            out.println("The number does not exist!");
            return;
        }
    }
}

I think you should redesign your code by splitting different activities with separate methods. It makes your code clear to understand.

public class Main {

    public static void main(String[] args) {
        int[] arr = createArray(100);
        System.out.println(isNumberExist(arr, 17) ? "The number was found!"
                                                  : "The number does not exist!");
    }

    public static int[] createArray(int total) {
        int[] arr = new int[total];
        Random random = new Random();

        for (int i = 0; i < arr.length; i++)
            arr[i] = random.nextInt(arr.length);

        return arr;
    }

    public static boolean isNumberExist(int[] arr, int x) {
        for (int i = 0; i < arr.length; i++)
            if (arr[i] == x)
                return true;

        return false;
    }

}

edited Jan 19, 2022 at 22:42

answered Jan 19, 2022 at 22:37

Oleg Cherednik

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2 Comments

MadProgrammer Over a year ago

Why not while (pos < numbers.length) or even just a for-loop which would seem to be a overall simpler construct for the problem (just saying ;))

Oleg Cherednik Over a year ago

Yep, there are different options.

Johann Schwarze · Accepted Answer · 2022-01-19 22:42:07Z

0

You should add a while loop to your test method, like this:

public static void test(PrintWriter out) {
    int x = 17;
    int pos = 0;
    while(pos < numbers.length) {
        if(numbers[pos] == x) {
            out.println("The number was found!");
            out.flush();
            break;
        }
        
        pos++;
    }
    
    if(pos == numbers.length) {
        out.println("The number does not exist!");
        out.flush();
    }
}

In your method, the if statement will only be executed once.

answered Jan 19, 2022 at 22:42

Johann Schwarze

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