Difference between Set and List (Set vs List)

Set: an Interface available in "java.util" package.

• a collection that cannot contain duplicate elements
• generally order of the elements does not matter
  
• models the mathematical set abstraction and is used to represent sets, such as the card comprising a poker hand

List: an Interface available in "java.util" package

• a collection that can contain duplicate elements
• it is an ordered collection, also called as a sequence
• user of a List generally has control over where in (at what index) the List the user want to insert an element and access it using its index

When you access the Set using its Iterator, it doesn't guarantee the order of elements, whereas when you access the List using its Iterator, it gives you a sequential access to the elements in the list one by one.

For the better understanding, you can just execute the example program in my previous post "How Do I Convert Set into List".

Converting an Array to a List

Java Collections API has very useful methods to play with all the data structures. Conversion between the collections made so easy.

following line of code converts an array into a list.
List list = Arrays.asList(str); // str is an array

Following program converts an array of strings into a List.

package com.blog.javaexposure.util;

import java.util.Arrays;
import java.util.List;

public class Array2List {

public static void main(String rags[]){
// Creating a string array
String[] str = {"One","Two","Three","Four","Five"};

// Convert array to List
List list = Arrays.asList(str);

System.out.println("Elements in the list are:");
//Checking the elements in the list
for(String s : list){
System.out.println(s);
}
}
}

How do I convert Set into List?

Conversion between the collections made pretty easy in Java.

Converting from a Set/List to List/Set can be done by passing the Set/List instance to the constructor of List/Set such as ArrayList/HashSet respectively.

Following line of code performs the conversion (from Set to List):

Set