Equal values ​​in java list

Question

How can I do to see the result of two or more identical numbers contained in the list. Everything should be based on lists, the code itself is simple, but I have no idea how to achieve the same print screen value. A.

All this is done under the 5 numbers entered in the list.

Example:

Enter 1 - 2 - 3 - 3 - 4

And the number 3 will be displayed. Repeats.

This is my code:

package generarlista; import java.util.*; public class GenerarLista { /** * @param args the command line arguments */ public static void main(String[] args) { int num; Scanner read = new Scanner (System.in); List<Integer> lista = new ArrayList<>(); System.out.println("A list of 5 integers is generated and printed equal values\n"); for (int i=1; i<6; i++){ System.out.println("Enter the value "+ i +" element to populate the list"); num = read.nextInt(); lista.add(num); } System.out.println("Data were loaded \n"); System.out.println("Values in the list are: "); Iterator<Integer> nameIterator = lista.iterator(); while(nameIterator.hasNext()){ int item = nameIterator.next(); System.out.print(item+" / "); } System.out.println("\n"); System.out.println("Equals are: "); } } 

Thank you very much!

Answer 1

There are many different approaches that could solve this problem. This is the first thing that occurred to me to sort the ArrayList and check the neighboring characters.

 package generarlista; import java.util.*; public class GenerarLista { /** * @param args the command line arguments */ public static void main(String[] args) { int num; Scanner read = new Scanner (System.in); List<Integer> lista = new ArrayList<>(); System.out.println("A list of 5 integers is generated and printed equal values\n"); for (int i=1; i<6; i++){ System.out.println("Enter the value "+ i +" element to populate the list"); num = read.nextInt(); lista.add(num); } System.out.println("Data were loaded \n"); System.out.println("Values in the list are: "); Collections.sort(lista); List<Integer> duplicates = new ArrayList<>(); for (int i = 0; i < lista.size(); i++) { System.out.print(lista.get(i) + " "); if (i < lista.size()-1 && lista.get(i) == lista.get(i+1)) if (!duplicates.contains(lista.get(i)) duplicates.add(lista.get(i)); } System.out.println("\n"); System.out.println("Equals are: "); for (int i = 0; i < duplicates.size(); i++) { System.out.print(duplicates.get(i) + " "); } } }