Question

in my java class we were learning about arrays and this question came up. I have tried to solve it and can’t seem to fulfill the requirements. I can read in the user inputs and have it limited to only 5 elements (one of the other requirements), also the values have to be between 10 and 100 I have also done that. But I cannot seem to “not print” the duplicate values. The array accepts the duplicate values. They don’t have to be taken out, just not printed. Here is my code so far:

import java.util.Arrays;
import java.util.Scanner;

public class ArrayTest {

static Scanner in = new Scanner(System.in);

public static void main(String[] args) {

    int size = 5;
    int InpNum[] = new int[size];

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

    while (InpNum[i] <= i){

        System.out.println("Please type a number between 10 and 100: ");
        InpNum[i] = in.nextInt();

        while (InpNum[i] < 10 || InpNum[i] > 100){
            System.out.println("Error: Please type an integer between 10 and 100: ");
            InpNum[i] = in.nextInt();
        }

        Arrays.sort(InpNum);

        System.out.println(Arrays.toString(InpNum));

        }

        while (Search(InpNum, i) == true){
            System.out.println("ERROR: Please enter a number that is not a duplicate of the other numbers you have entered");
            InpNum[i] = in.nextInt();
        }

    }

}

// I can't seem to implement the method below in a useful manner.

    public static boolean Search(int InpNum[], int searchedNum) {

    for(int i : InpNum) {

        if (i == searchedNum) {

            return true;
        }
    }

    return false;
}
}   

Answer 1

I would consider restructuring your application.

Instead of placing the number the user inputs into the array immediately, store it in a local variable. Then run all the checks you need to run, and add it to the array only if it passes all of them.

You should only have one while loop in the whole program (the outer one). All those others are greatly confusing the issue and making the problem much harder than it has to be.

So, in psudo-code:

int index = 0;
while (true)
{
  int num = in.nextInt();

  // if not between 10 and 100, continue
  // if it would make the array larger than 5, continue
  //    (or perhaps break out of the loop, since we've filled the array)
  // if it is already in the array, continue

  // all the checks passed, so add it to the array!
  InpNum[index++] = num;
}

---

As a side note, what you really need is a Set. This is a collection which is guaranteed to have no duplicates and allows you to answer the question “do I contain this value?” in an efficient manner using the method Set.contains( Object ).

So I would create a TreeSet or HashSet and put every number the user types into it. Your Search function would then simply be a one liner calling contains( searchedNum ) on your set.