Question

方法定义LibraryBook是 void方法，但在其定义的开头没有void。为什么不会导致错误？我尝试了另一个方法定义而另一个确实导致了错误：invalid method declaration。

/**
/The following is a definition of the LibraryBook class.
/This class has four instance variables and one static (or class) variable.
/One of the instance variables is a type Author.
**/
public class LibraryBook
{
    private int bookId;
    private String bookName;
    private Author bookAuthor;
    private double bookPrice;
    private static double totalInvValue;


    public LibraryBook (int id, String name, Author author, double price)
    {
        bookId = id;
        bookName = name;
        bookAuthor = author;
        bookPrice = price;
        totalInvValue += price;
    }


    public String toString()
    {
        String response = "";
        response += "Book Name is: " + bookName;
        response += "\nIt costs: " + bookPrice;
        response += "\nIt was " + bookAuthor.toString();
        return response;
    }


    public static double getTotValue()
    {
        return totalInvValue;
    }

}

Answer 1

你知道它是一个构造函数，因为它与类本身的名称完全相同。

Class-name =构造函数名称

它不是一种方法，因为它不是一种方法。

在实例化Object时使用。

Answer 2

构造函数不是它们不返回任何东西的方法

为什么在方法定义的头部没有void的void方法不会导致错误？

2 个答案: