java - 为什么方法定义头部没有 void 的 void 方法不会导致错误？

Question

这个问题已经有答案了:

Methods vs Constructors in Java (11 个回答)

已关闭 8 年前。

方法定义LibraryBook是一个 void 方法，但它没有 void在其定义的头部。为什么它不会导致错误？我尝试另一个方法定义，另一个确实导致错误: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

您知道它是一个构造函数，因为它与类本身具有完全相同的名称。

类名=构造函数的名称

它不被用作一种方法，因为它不是一种方法。

它在实例化对象时使用。