使用 Get 方法仅提取数组列表中索引的某些部分

Question

我有一个由不同类型组成的数组列表。我想使用数组列表中的get方法从指定的索引中只提取一个元素

public BookCollection() {

    collection = new ArrayList<Book>(10);

}

public void addbook(String title, String author, int year, double cost, boolean Available) {

    Book a = new Book(title, director, year, cost, Available);

    collection.add(a);

}

在上面的代码中，我想创建一个图书库，但在某些时候我只想要标题。

public static void main(String[] args) {

    BookCollection library = new BookCollection();

    library.addbook("Pride & Prejudice", "Jane Austen", 1801, 24.95, true);

    System.out.println(collection.get(0).toString())

}

然后我只想得到标题。所以在这种情况下，它会是傲慢与偏见。目前输出是“傲慢与偏见Jane Austen180124.95”但我希望它只是“傲慢与偏见”。

Answer 1

collection.get(0).getTitle()?

Answer 2

技嘉的回答是对的。您应该在 Book 类中为每个字段创建 getter 方法，以便您可以随时单独调用。您还应该检查 Java 规则和约定，在这种特殊情况下，变量和方法名称应该以小写字母开头，因此您应该从“Available”切换到“available”。大写字母用于类。我尝试了您的代码并找到了解决方案，希望它适合您：这是 BookCollection 类：public class BookCollection extends ArrayList<Book>{private static final long serialVersionUID = 1L;private ArrayList<Book> collection;public BookCollection() {&nbsp; &nbsp; this.collection = new ArrayList<Book>();}public void addbook(String title, String author, int year, double cost, boolean available) {&nbsp; &nbsp; Book a = new Book(title, author, year, cost, available);&nbsp; &nbsp; this.add(a);}public static void main(String[] args) {&nbsp; &nbsp; BookCollection library = new BookCollection();&nbsp; &nbsp; library.addbook("Pride & Prejudice", "Jane Austen", 1801, 24.95, true);&nbsp; &nbsp; System.out.println(library.get(0).isAvailable());}}这是 Book 类，带有 getter 和 setter：public class Book {private String name;private String author;private int year;private double cost;private boolean available;public Book(String name, String author, int year, double cost, boolean available){&nbsp; &nbsp; this.name = name;&nbsp; &nbsp; this.author = author;&nbsp; &nbsp; this.year = year;&nbsp; &nbsp; this.cost = cost;&nbsp; &nbsp; this.available = available;}public String getName() {&nbsp; &nbsp; return name;}public void setName(String name) {&nbsp; &nbsp; this.name = name;}public String getAuthor() {&nbsp; &nbsp; return author;}public void setAuthor(String author) {&nbsp; &nbsp; this.author = author;}public int getYear() {&nbsp; &nbsp; return year;}public void setYear(int year) {&nbsp; &nbsp; this.year = year;}public double getCost() {&nbsp; &nbsp; return cost;}public void setCost(double cost) {&nbsp; &nbsp; this.cost = cost;}public boolean isAvailable() {&nbsp; &nbsp; return available;}public void setAvailable(boolean available) {&nbsp; &nbsp; this.available = available;}}