Exercise: Sets

Create a set from a list

Task Description:

The following steps will show you how to create a unique set from a list of phone numbers.

Task List:

Create a new package under the src folder named setExample

Create a new class SetExcercise in the ** setExample** package

Create a main function: public static void main(String[] args){}

Create a list of numbers: List<String> numbers = new ArrayList<String>();

Add numbers to the list. Be sure to add multiple duplicate numbers.

Create a set and add the list to its constructor: Set<String> uniqueNumbers = new HashSet<String>(numbers);

Write a for-each loop to display the items in the set

Right click on the SetExcercise and select run

Task Feedback:

Nice work!

Solution

ND079 C1 L6 A05 Set Exercise Solution

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class SetExcercise {

    public static void main(String[] args) {
        List<String> numbers = new ArrayList<String>();

        // We have a list of numbers and some are duplicates
        numbers.add("123-222-3333");
        numbers.add("223-222-3333");
        numbers.add("123-332-3333");
        numbers.add("123-222-4433");
        numbers.add("123-222-1133");
        numbers.add("123-222-3333");
        numbers.add("123-222-3333");
        numbers.add("123-232-4533");
        numbers.add("123-562-3333");
        numbers.add("123-000-3333");
        numbers.add("555-222-3333");
        numbers.add("444-222-3333");

        // Add them to a Set to get a unique list
        Set<String> uniqueNumbers = new HashSet<String>(numbers);

        for (String number : uniqueNumbers) {
            System.out.println(number);
        }
    }
}