2D Array + Duplicates

package project;

import java.util.ArrayList;
import java.util.Scanner;

public class Project {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int row, col;
        System.out.println("Enter number of rows:");
        row = input.nextInt();
        System.out.println("Enter number of columns:");
        col = input.nextInt();
        int[][] array = new int[row][col];
        ArrayList<Integer> _1dArray = new ArrayList();
        ArrayList<Integer> dupList = new ArrayList();
        System.out.print("You need " + (row * col) + " elements, ");
        for (int i = 0; i < row; i++) {
            System.out.println("Enter " + col + " numbers for row " + i + ":");
            for (int j = 0; j < col; j++) {
                array[i][j] = input.nextInt();
            }
        }
        System.out.println("Your array is:");
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col; j++) {
                System.out.print(array[i][j] + "\t");
            }
            System.out.println("");
        }
        for (int[] r : array) {
            for (int c : r) {
                _1dArray.add(c);
            }
        }
        for (int i = 0; i < _1dArray.size(); i++) {
            for (int j = i + 1; j < _1dArray.size(); j++) {
                if (_1dArray.get(i) == _1dArray.get(j)) {
                    if (!dupList.contains(_1dArray.get(i))) {
                     dupList.add(_1dArray.get(i));
                    }
                }
            }
        }
        if (dupList.size() > 0) {
            System.out.println(dupList.size() + " duplicates found:");
            for (int dupped : dupList) {
                System.out.println(dupped);
            }
        }
    }
}