List of contrast with the use Hashset

Hashset stored data is unique and random , using HashMap underlying data store, there is a value in the key hashmap the PRESENT, value is defined internally.

package com.devin.java8.newCharacteristics;

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

public class HashSetDemo {
public static void main(String[] args) {
	Set<String> hashSet = new HashSet<>();
	hashSet.add("d");
	hashSet.add("b");
	hashSet.add("e");
	hashSet.add("a");
	hashSet.add("b");
	hashSet.add("c");
	hashSet.add("c");
	hashSet.forEach(System.out::println);
}
}

The results are:

a
b
c
d
e

List data is stored orderly and repeatable. Using an array or a linked list to store data. The memory array is Arraylist data.

package com.devin.java8.newCharacteristics;

import java.util.ArrayList;
import java.util.List;

public class ArrayListDemo {
	public static void main(String[] args) {
		List<String> list = new ArrayList<>();
		list.add("d");
		list.add("b");
		list.add("e");
		list.add("a");
		list.add("b");
		list.add("c");
		list.add("c");
		
		list.forEach(System.out::println);
	}
}

The output is:

d
b
e
a
b
c
c