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//Represents list books command for biblioteca
public class ListBooksCommand implements Command {
private static final String BOOKS = "Books::";
private static final String FORMAT = "%-35s %-35s %-35s";
private static final String HEADER = String.format(FORMAT, "Name", "Author", "YearPublished");
private static final String NO_BOOKS_AVAILABLE = "No Books Available";
private final Biblioteca biblioteca;
private final IO io;
public ListBooksCommand(Biblioteca biblioteca, IO io) {
this.biblioteca = biblioteca;
this.io = io;
}
@Override
public void execute() {
if (this.biblioteca.isEmpty(Book.class)) {
this.io.println(NO_BOOKS_AVAILABLE);
return;
}
this.displayBooks();
}
private void displayBooks() {
this.io.println(BOOKS);
this.io.println(HEADER);
this.io.println(this.biblioteca.representationOfAllLibraryItems(Book.class));
}
}
public class ListMoviesCommand implements Command {
private static final String Movies = "Movies::";
private static final String FORMAT = "%-35s %-35s %-35s";
private static final String HEADER = String.format(FORMAT, "Name", "Director", "YearPublished");
private static final String NO_BOOKS_AVAILABLE = "No Movies Available";
private final Biblioteca biblioteca;
private final IO io;
public ListBooksCommand(Biblioteca biblioteca, IO io) {
this.biblioteca = biblioteca;
this.io = io;
}
@Override
public void execute() {
if (this.biblioteca.isEmpty(Movie.class)) {
this.io.println(NO_MOVIES_AVAILABLE);
return;
}
this.displayMovies();
}
private void displayMovies() {
this.io.println(MOVIES);
this.io.println(HEADER);
this.io.println(this.biblioteca.representationOfAllLibraryItems(MOVIE.class));
}
}
我在这里有两个类，一个是listbooks命令，listmovies命令都在biblioteca上执行。 Book和Movie都是类型LibraryItem（接口）。 以下两个代码都是一样的。两者都会要求biblioteca获得自己类型的代表性。这两个命令都会显示该表示。如何删除重复？
这是藏书实现
//Represents a library
public class Biblioteca {
private final List<LibraryItem> allLibraryItems;
public String representationOfAllLibraryItems(Class<? extends LibraryItem> itemType) {
return this.allLibraryItems
.stream()
.filter(libraryItem -> libraryItem.getClass().equals(itemType))
.map(LibraryItem::representation)
.collect(Collectors.joining(LINE_SEPARATOR));
}
public boolean isEmpty(Class<? extends LibraryItem> itemType) {
return this.allLibraryItems.stream().noneMatch(libraryItem -> libraryItem.getClass().equals(itemType));
}
}
请建议我的模式，以避免重复。
这些类型的'执行命令'似乎是错误的。他们应该实现/扩展处理这种bookeping的父类型（例如'LibraryItem'抽象类 - 你已经提到这种类型已经存在）。如果存在任何这样的项目，抽象类应该处理询问“Biblioteca”，以便子类只关心它们如何显示。 – dimo414
你的问题有点不清楚。你说的是，下面的代码都是类似的。你在说什么代码？ –
这两个listbooksCommand，ListMoviesCommand都有相同的代码。 – Srinivas