In C++, the code Card cards[20]; initializes 20 Card objects, whereas in Java, the code Card[] cards = new Card[20]; initializes an array that can hold 20 Card objects, but the Card objects aren't actually initialized. You have to do
for (int i = 0; i < cards.length; i++) {
cards[i] = new Card();
}
Is there any way to avoid having to do this in Java, similar to C++?
No, there is not.
Array elements are values.
For reference types, that value is a reference. The default initialization value for references is null. That's the value that each element in the array will be initialized to. You have to explicitly initialize the elements yourself to reference new objects.
For primitive types, that value is the primitive type value, a char, an integer, a floating point value, or a boolean. The default value for those is '\u0000', 0, 0.0, and false, respectively. That's the value that each element in the array will be initialized to.
false. Are you asking me to add that to the answer? I'll do that now.
'\u0000' for charNo, there is no purely-array-way of doing what you want. If you don't want to use loops explicitly for this problem, then one of alternative ways could be using streams (added in Java 8).
Card[] cards = Stream.generate(Card::new).limit(20).toArray(Card[]::new);
or maybe using Arrays.setAll will be less cryptic
Card[] cards = new Card[20];
Arrays.setAll(cards, i -> new Card());
setAll version reads much clearer, and may actually be a better choice than the loop.The C++ equivalent of a Java Card[] cards = new Card[20]; would roughly be Card* cards[20]; (or std::array<Card*, 20> cards; in modern C++).
And as it turns out, you have to explicitly initialize every array element in C++ as well, if you want those pointers to actually point to Card objects in memory:
for (int i = 0; i < 20; ++i)
{
cards[i] = new Card;
}
There is no Java equivalent for the C++ Card card[20], for the same reason that there is no Java equivalent for a C++ Card single_card;.