Java:对象数组中的对象数组

Question

我正在构建一个库程序，它有 4 个类:

• Books ==> 包含一本书的标题
• Genre ==> 包含流派的名称和书籍的对象数组
• Library ==> 包含流派的对象数组
• 应用程序==>包含对话框和扫描仪

您将能够从应用类创建新的流派数组和新的图书数组。

public class App{
  Library library = new Library();

  //the other stuff

  private void run(){
     library.addGenres(insertGenreNameHere);
  }
}


public class Library{
   private Genres[] genres = new Genres[5];    //Obj. Array of genres
   private Int nrOfGenres = 0;                 //number of how many genres there are in an array

    public void addGenres(String genreName){   //adds a new genre to the array
       if (nrOfGenres < genres.length) {
        genres[nrOfGenres] = new Genres(genreName);
        nrOfGenres++;
    }
    else {
        System.out.println("You already have the maximum of " + genres.length + " genres!");
    }
}



public class Genres {

   private String name;
   private Books[] books = new Books[5];        //Obj. Array of books
   private int nrOfBooks = 0;                   //number of how many books there are in an array

   public Genres(String name) {                 //Constructor
       this.name = name;
   }

   //getter & setter for the name of the genre

   public void addBooks(String titel){          //adds new book to the array
      if (nrOfBooks < books.length) {
         books[nrOfBooks] = new Books(titel);
         nrOfBooks++;
    }
    else {
        System.out.println("You already have the maximum of " + books.length + " books!");
    }
}

public void showBooks(){                        //prints the books line by line
    int x = 0;
    while(x < books.length && books[x] != null) {
        System.out.println(books[x].getTitle());
        x++;
    }
  }
}



public class Books(){
   private String title;

   public Books(String title){                  //Constructor
      this.title = title;
   }

   //getter & setter for the title
}

但是我还不知道如何将一本书添加到其类型中，甚至不知道应该如何“联系”(？)一本书

如果我是对的，我不能这样做 流派流派 = new Genre(); 或 书籍 books = new Book() ;因为它必须在数组中(？)

如果有人能帮助我，我会非常高兴，并乐意在需要时分享更多信息

干杯马丁

Answer 1

你确定书籍数量和类型数量会保持不变吗？我相信将书籍和流派从数组转换为 ArrayList 应该可以帮助您实现程序的顺利运行。您无需计算书籍数量和流派数量。当您使用 ArrayList 及其 size() 方法时，事情会变得简单得多。