The comment of the previous folk is totally right. You are not adding the created cards to the list.

Try replacing your code

final List<Card> deck = Stream.of(CardType.values()). flatMap(type -> IntStream.rangeClosed(1, 4).mapToObj(num -> new Card(type, "CardName" + num))). collect(toList()); 

for standard list creation and adding. For instance (and updated for 4 cards):

List<Card> deck = new ArrayList<Card>(); for (int i = 0; i < 4; i++){ deck.add(card1); deck.add(card2); deck.add(card3); } 

If you want to minimise the number of lines of code, there are ways to initialise a new list with content. Try this post Initialization of an ArrayList in one line.

Anyway, always try to code the simplest solution, even more when starting with a new language.

The comment of the previous folk is totally right. You are not adding the created cards to the list.

Try replacing your code

final List<Card> deck = Stream.of(CardType.values()). flatMap(type -> IntStream.rangeClosed(1, 4).mapToObj(num -> new Card(type, "CardName" + num))). collect(toList()); 

for standard list creation and adding. For instance (and updated for 4 cards):

List<Card> deck = new ArrayList<Card>(); for (int i = 0; i < 4; i++){ deck.add(card1); deck.add(card2); deck.add(card3); } 

If you want to minimise the number of lines of code, there are ways to initialise a new list with content. Try this post Initialization of an ArrayList in one line.

Anyway, always try to code the simplest solution, even more when starting with a new language.

The comment of the previous folk is totally right. You are not adding the created cards to the list.

Try replacing your code

final List<Card> deck = Stream.of(CardType.values()). flatMap(type -> IntStream.rangeClosed(1, 4).mapToObj(num -> new Card(type, "CardName" + num))). collect(toList()); 

for standard list creation and adding. For instance:

List<Card> deck = new ArrayList<Card>(); deck.add(card1); deck.add(card2); deck.add(card3); 

The comment of the previous folk is totally right. You are not adding the created cards to the list.

Try replacing your code

final List<Card> deck = Stream.of(CardType.values()). flatMap(type -> IntStream.rangeClosed(1, 4).mapToObj(num -> new Card(type, "CardName" + num))). collect(toList()); 

for standard list creation and adding. For instance (and updated for 4 cards):

List<Card> deck = new ArrayList<Card>(); for (int i = 0; i < 4; i++){ deck.add(card1);  deck.add(card2);  deck.add(card3); } 

If you want to minimise the number of lines of code, there are ways to initialise a new list with content. Try this post Initialization of an ArrayList in one line.

Anyway, always try to code the simplest solution, even more when starting with a new language.