Java 将方法转换为 lambda 表达式

Question

what this method should look like in lambda expression?

public Book returnBook(int idBook){
   for (Book b : records){
        if(b.getIdBook() == idBook){
            return b;
        }
    }

    return null;
}

Answer 1

The stream version would primarily be made of filter + findFirst

return records.stream()
              .filter(book -> book.getIdBook() == idBook)
              .findFirst()
              .orElse(null);

Answer 2

what this method should look like in lambda expression?

public Book returnBook(int idBook){
   for (Book b : records){
        if(b.getIdBook() == idBook){
            return b;
        }
    }

    return null;
}