Question

Write a program FindDuplicate.java that reads n integer arguments from the command line into an integer array of length n, where each value is between is 1 and n, and displays true if there are any duplicate values, false otherwise.

Answer 1

Answer:

1. public class FindDuplicate{
3.    public static void main(String[] args) {
4.        Scanner input = new Scanner(System.in);
6.        int n = 5;
7.        int arr[] = new int[n];
9.        for(int i=0; i < arr.length; i++){
10.            int inputNum = input.nextInt();
11.            if(inputNum >=1 && inputNum <=n) {
12.                arr[i] = inputNum;
13.            }
14.        }
16.        for(int j =0; j < arr.length; j++){
17.            for(int k = 0; k < arr.length; k++){
18.                if(j == k){
19.                    continue;
20.                }else{
21.                    if(arr[j] == arr[k]){
22.                        System.out.println("True");
23.                        return;
24.                    }
25.                }
26.            }
27.        }
28.        System.out.println("False");
29.    }
30. }

Explanation:

Firstly, create a Scanner object to get user input (Line 4).

Next, create an array with n-size (Line 7) and then create a for-loop to get user repeatedly enter an integer and assign the input value to the array (Line 9 - 14).

Next, create a double layer for-loop to check the each element in the array against the other elements to see if there is any duplication detected and display "True" (Line 21 - 22). If duplication is found the program will display True and terminate the whole program using return (Line 23). The condition set in Line 18 is to ensure the comparison is not between the same element.

If all the elements in the array are unique the if block (Line 21 - 23) won't run and it will proceed to Line 28 to display message "False".