Checking if an array contains certain integers

Question

I am making an Array that is 10 integers long, so that each place 0-9 contains a different integer 0-9.

I am having trouble figuring out how to check if the array already contains a certain number, and if so, regenerating a new one.

So far I have:

for (int i = 0; i < perm.length; i++)
{
    int num = (int) (Math.random() * 9); 
    int []

    perm[i] = num;   
}

Railey

The accepted answer is not correct. Have u checked it??? – Remy

Possible duplicate of Java, Simplified check if int array contains int – Factorial

Answer 1

Arrays.asList(perm).contains(num) 

from How can I test if an array contains a certain value?

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

this is not enough to loop like this, if collision happens some slots would have been not initalized.

Overall, for this task you better initialize array with values in order and then shuffle it by using random permutation indexes

Diggins

I am new to java and just started learning about arrays. Could you give me an example of what you mean or explain it? – Railey

@user1729448, explain about what? Have you followed the provided links? – Diggins

Then Arrays.asList(perm).contains(num) answers you question exactly. – Diggins

Never mind I understand it. So if the num is on the list it returns true? – Railey

@user1729448, yes, it should. – Diggins

let us continue this discussion in chat – Railey

This is wrong.. Arrays.asList(perm) returns a List<int[]>. contains may not always be true, even if the number is in there. – Pierce

This is wrong. in contains(num) num should be an object. But it will never be the same object even if that number was found early. Because here for each int value a new Integer object is created and passed into the method. – Remy

This will only work for Integer object. Not with primitive int. – Peroxidase

This is wrong...per the above comments from @WaiYan – Barbule

Answer 2

here is a complete answer

int[] array = {3,9, 6, 5, 5, 5, 9, 10, 6, 9,9};

    SortedSet<Integer> s = new TreeSet();
    int numberToCheck=61;
    for (int i = 0; i < array.length; i++) {
        s.add(array[i]);
    }

    System.out.println("Number contains:"+!(s.add(numberToCheck)));


    System.out.println("Sorted list:");
    System.out.print(s);

Remy

Why do you need to define "mode" and "maxCount" variabled? – Atman

Sorry for the confusion. They are not needed. I edited the answer removing them – Remy

Answer 3

Adding both string and integer to check is exist or not.

public class existOrNotInArray {

public static void elementExistOrNot() {
    // To Check Character exist or not
    String array[] = { "AB", "CD", "EF" };

    ArrayList arrayList = new ArrayList<>();

    String stringToCheck = "AB";

    for (int i = 0; i < array.length; i++) {
        arrayList.add(array[i]);
    }

    System.out.println("Character exist : " + arrayList.contains(stringToCheck));

    // To Check number exit or not
    int arrayNum[] = { 1, 2, 3, 4 }; // integer array

    int numberToCheck = 5;

    for (int i = 0; i < arrayNum.length; i++) {
        arrayList.add(arrayNum[i]);
    }
    System.out.println("Number exist :" + arrayList.contains(numberToCheck));
}

public static void main(String[] args) {
    elementExistOrNot();
}
}

Bernetta