Need to figure out how to replace the comma in the array list for a space

Question

I have tried to use replaceAll and removeAll but still can't change the list without commas. I tried to add after list + ""); but nothing changed. Still get the output with commas. I need to remove the commas in the output. Need only one white space between numbers. (See at the end the output)

(Remove duplicates) Write a method that removes the duplicate elements from an array list of integers using the following header:
public static void removeDuplicate(ArrayList<Integer> list)
Write a test program that prompts the user to enter 10 integers to a list and displays the distinct integers separated by exactly one space.

package exercise11_13;

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

public class Exercise11_13 {

    /**
     * @param args the command line arguments
     */
    // Main method
    public static void main(String[] args) {
        // Create de Scanner object.
        Scanner input = new Scanner(System.in);
        
        // Prompt the user to enter ten integer numbers. 
        System.out.print("Please, enter ten (10) integers numbers: ");
        
        // Create the ListArray (List object).
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < 10; i++) list.add(input.nextInt());

        removeDuplicate(list);
        
        System.out.println("Display the distinct integers in their input order "
                + "and seperated by exactly one space: " + "\n" + list );
    }

    public static void removeDuplicate(ArrayList<Integer> list) {

        ArrayList<Integer> temp = new ArrayList<>();
        for (int i = 0; i < list.size(); i++) {

            if (!temp.contains(list.get(i))) {
                temp.add(list.get(i));
            }
        }
        list.clear();
        list.addAll(temp);
        
    }
}

Output: I need to remove the commas in the output. Need only one white space between numbers. run:

Please, enter ten (10) integers numbers: 78
99
54
63
56
78
63
14
67
99
Display the distinct integers in their input order and seperated by exactly one space: 
[78, 99, 54, 63, 56, 14, 67]
BUILD SUCCESSFUL (total time: 27 seconds)

Answer 1

There are two ways to replace the commas for white space in this program.

The long one: Need to add: import java.util.stream.Collectors;

System.out.println("Display the distinct integers in their input "
                + "order and separated by exactly one space: "
                + "\n" 
                + 
                list.stream().map(Object::toString).collect(Collectors.joining("")));

The short one:

System.out.println("\nDisplay the distinct integers in their input "
                + "order and separated by exactly one space: "
                + "\n" + list.toString().replaceAll("[,\\[\\]]", ""));  

Below the entire program.

package exercise11_13;

import java.util.ArrayList;
import java.util.Scanner;
import java.util.stream.Collectors;

    public class Exercise11_13 {
    
        /**
         * @param args the command line arguments
         */
        // Main method
        public static void main(String[] args) {
            // Create de Scanner object.
            Scanner input = new Scanner(System.in);
            
            // Prompt the user to enter ten integer numbers. 
            System.out.print("Please, enter ten (10) integers numbers: ");
            
            // Create the ListArray (List object).
            ArrayList<Integer> list = new ArrayList<>();
            for (int i = 0; i < 10; i++) list.add(input.nextInt());
    
            removeDuplicate(list);
            /**
            System.out.println("Display the distinct integers in their input "
                    + "order and separated by exactly one space: "
                    + "\n" + 
            list.stream().map(Object::toString).collect(Collectors.joining(" ")));
            */
            System.out.println("\nDisplay the distinct integers in their input "
                    + "order and separated by exactly one space: "
                    + "\n" + list.toString().replaceAll("[,\\[\\]]", ""));         
        }
    
        public static void removeDuplicate(ArrayList<Integer> list) {
    
            ArrayList<Integer> temp = new ArrayList<>();
            for (int i = 0; i < list.size(); i++) {
    
                if (!temp.contains(list.get(i))) {
                    temp.add(list.get(i));
                }
            }
            list.clear();
            list.addAll(temp);
            
        }
    }

Answer 2

As the question is tagged with replaceAll, it is indeed possible to remove all "redundant" characters supplied by List::toString method (brackets and commas) using a regular expression [,\[\]] (brackets should be escaped with \):

List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
System.out.println(list.toString().replaceAll("[,\\[\\]]", "")); // 1 2 3 4 5

Or, knowing that the brackets are the first and the last characters, they can be removed with the help of substring and then apply String::replace:

String str = list.toString();
    
System.out.println(str.substring(1, str.length() - 1).replace(",", "")); // 1 2 3 4 5

Answer 3

When you use an object like that, it's implicitly converted to a string by its toString method. You shouldn't rely on the list's implementation of toString, but instead convert it to the string you need yourself. Here, you could stream the list and join it with a space:

System.out.println(
   "Display the distinct integers in their input order and separated by exactly one space: \n" + 
   list.stream().map(Object::toString).collect(Collectors.joining(" "))
);