Set Interface Example



The Set interface

- contains no duplicate elements

- can contain at most one null element.

- does not provide any ordering guarantees.

The following example explains how to iterate through a Set in various Java versions including Java 8.

             	

			
			


package com.smoothexample.java.set;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class SetExample {
	public static void main(String[] args) {
		Set<String> set = new HashSet<String>();

		populateValues(set);

		System.out.println("Using for loop");
		for (String s : set) {
			System.out.println(s);
		}
		System.out.println("----------------------------------------------------------------------");
		System.out.println("Using iterator");
		System.out.println("----------------------------------------------------------------------");

		Iterator<String> iterator = set.iterator();
		while (iterator.hasNext()) {
			System.out.println(iterator.next());
		}

		System.out.println("----------------------------------------------------------------------");
		System.out.println("Using Java8 - Singlestatement in foreach");
		System.out.println("----------------------------------------------------------------------");

		set.forEach(name -> System.out.println(name));

		System.out.println("----------------------------------------------------------------------");
		System.out.println("Using Java8 - multiple statements in foreach");
		System.out.println("----------------------------------------------------------------------");

		set.forEach(name -> {
			String s = "Printing name " + name;
			System.out.println(s);
		});

	}

	private static void populateValues(Set set) {
		for (int i = 1; i <= 10; i++) {
			String s = "name" + i;
			set.add(s);
		}
	}

}


Sample output


			
			
Using for loop
name6
name5
name4
name3
name9
name10
name8
name7
name2
name1
----------------------------------------------------------------------
Using iterator
----------------------------------------------------------------------
name6
name5
name4
name3
name9
name10
name8
name7
name2
name1
----------------------------------------------------------------------
Using Java8 - Singlestatement in foreach
----------------------------------------------------------------------
name6
name5
name4
name3
name9
name10
name8
name7
name2
name1
----------------------------------------------------------------------
Using Java8 - multiple statements in foreach
----------------------------------------------------------------------
 Printing name name6
 Printing name name5
 Printing name name4
 Printing name name3
 Printing name name9
 Printing name name10
 Printing name name8
 Printing name name7
 Printing name name2
 Printing name name1