File size: 2,253 Bytes
63f6453 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
/**
* Kütüphane ödünç sistemi — arayüz (sözleşme) testleri için örnek.
* Genel API:
* addBook(isbn, title) -> boolean (yeni eklendiyse true)
* borrow(isbn, member) -> IllegalStateException (ödünçte), NoSuchElementException (yok)
* giveBack(isbn) -> Optional<String> (iade eden üye)
* borrowedBy(member) -> List<String> isbn (alfabetik sıralı)
* isAvailable(isbn) -> boolean
* Bir üye en fazla MAX_LOANS kitap ödünç alabilir.
*/
public class Library {
public static final int MAX_LOANS = 3;
private final Map<String, String> titles = new HashMap<>();
private final Map<String, String> loans = new HashMap<>();
public boolean addBook(String isbn, String title) {
if (isbn == null || isbn.isBlank() || title == null || title.isBlank()) {
throw new IllegalArgumentException("isbn and title are required");
}
return titles.putIfAbsent(isbn, title) == null;
}
public void borrow(String isbn, String member) {
if (!titles.containsKey(isbn)) {
throw new java.util.NoSuchElementException("unknown book: " + isbn);
}
if (loans.containsKey(isbn)) {
throw new IllegalStateException("already borrowed");
}
if (borrowedBy(member).size() >= MAX_LOANS) {
throw new IllegalStateException("loan limit reached");
}
loans.put(isbn, member);
}
public Optional<String> giveBack(String isbn) {
return Optional.ofNullable(loans.remove(isbn));
}
public List<String> borrowedBy(String member) {
List<String> out = new ArrayList<>();
for (Map.Entry<String, String> e : loans.entrySet()) {
if (e.getValue().equals(member)) {
out.add(e.getKey());
}
}
out.sort(String::compareTo);
return out;
}
public boolean isAvailable(String isbn) {
return titles.containsKey(isbn) && !loans.containsKey(isbn);
}
public int bookCount() {
return titles.size();
}
}
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