java - 从 actionPerformed 中访问对象

Question

我正在为大学做一个书店 GUI，

我有 4 个类:Book、bookfile、BookGUI、TestClass。

我在测试中创建了一个 bookFile() 对象 (bkf)，并向其中添加了一个 Book (b )，然后创建我的 BookGUI(bkf) 对象 (g)，并将 bkf 传递给它.

我只能编辑 BookGUI 类!

我不知道如何从 actionPerformed() 中访问创建 BookGUI 对象时传入的 bkf 对象

当按下添加按钮时，我需要更新 bookFile() 中的 Arraylist， 如何从执行的操作中调用 bkf 对象上的 .addBook()？

请只回答我提出的问题，因为我会自己解决剩下的问题，除非这是良好的编码道德。

感谢您的帮助。

测试类

public class TestClass {

 public static void main(String[] args)
    {
        bookFile bkf = new bookFile();   
        Book b = new Book("Dan Brown","The daVinci Code",3,10.99);
        bkf.addBook(b);
        BookGUI g = new BookGUI(bkf);   
        g.setVisible(true);
    }
}

BookGUI

import javax.swing.*;
import javax.swing.border.TitledBorder;

import java.awt.*;
import java.awt.event.*;


class BookGUI extends JFrame implements ActionListener{

 private final int width = 290;
 private final int height = 260;
 private JLabel title, author, quantity, price; 
 private JTextField titleTBox, authorTBox, quantityTBox, priceTBox;
 private JTextArea  outputBox;
 private JButton addButton, totalQ, totalV, exit;
 private TitledBorder border;

 private Container c;

 private JPanel input = new JPanel(new GridLayout(0,2));
 private JPanel buttons = new JPanel(new GridLayout(2,2));
 private JPanel output = new JPanel(new FlowLayout());



 public BookGUI(bookFile bkf)
 {



     c = getContentPane();
     this.setLayout(new BorderLayout(2,2));
     this.setSize(width, height);

     this.add(input,BorderLayout.NORTH);
     input.setBackground(Color.LIGHT_GRAY);
     title = new JLabel("Title");
     input.add(title);


     titleTBox = new JTextField();
     input.add(titleTBox);

     author = new JLabel("Author");
     input.add(author);

     authorTBox = new JTextField();
     input.add(authorTBox);

     quantity = new JLabel("Quantity");
     input.add(quantity);

     quantityTBox = new JTextField();
     input.add(quantityTBox);

     price = new JLabel("Price");
     input.add(price);

     priceTBox = new JTextField();
     input.add(priceTBox);

     this.add(buttons,BorderLayout.CENTER);
     addButton = new JButton("Add");
     buttons.add(addButton);
     addButton.addActionListener(this);

     totalQ = new JButton("Total Quantity");
     buttons.add(totalQ);
     totalQ.addActionListener(this);

     totalV = new JButton("Total Value");
     buttons.add(totalV);
     totalV.addActionListener(this);

     exit = new JButton("Exit");
     buttons.add(exit);
     exit.addActionListener(this);

     this.add(output,BorderLayout.SOUTH);
     output.setBorder(new TitledBorder("Output"));
     outputBox = new JTextArea(3, 20);
     output.add(outputBox);




 }


public void actionPerformed(ActionEvent e) {

    if(e.getSource() == addButton)
    {


         int q = Integer.parseInt(quantityTBox.getText());
         double p = Double.parseDouble(priceTBox.getText());
         Book nb = new Book(titleTBox.getText(), authorTBox.getText(), q,     p);
         .addBook(nb);


        outputBox.setText(bkf.getDetails());
    }


}

}

图书文件

import java.util.ArrayList;

public class bookFile {

private ArrayList <Book> blist = new ArrayList<Book>();

public void addBook(Book b)
{
    blist.add(b);
}

public Book getBook(int i) {
    return blist.get(i);
}

// returns a string containing all the book details in the array list
public String getDetails()
{   
    String output="";
    for (int i=0;i<blist.size();i++)
    {
        output += (i+1)+"."+blist.get(i).getTitle() +","+ blist.get(i).getAuthor()+","
                + blist.get(i).getQuantity()+","+ blist.get(i).getPrice() +"\n";            
    }
    return output;
}

// returns the total quantity of books in the array list
public int gettotalQuantity()
{
    int total=0;
    for (int i=0;i<blist.size();i++)
    {
        total += blist.get(i).getQuantity();    
    }

    return total;
}

// returns the total value of books in the array list
public double gettotalValue()
{
    double total=0;
    for (int i=0;i<blist.size();i++)
    {
        total += (blist.get(i).getQuantity()*blist.get(i).getPrice());  
    }

    return total;
}

}

预订

public class Book {

//Member Variables:
private String author;
private String title;
private int quantity;
private double price;

public Book(String a, String t, int q, double p)
{
    author=a;
    title=t;
    quantity=q;
    price=p;
}
//Getters & Setters:
public String getAuthor()
{
    return author;
}
public void setAuthor(String a)
{
    author=a;
}
public String getTitle()
{
    return title;
}
public void setTitle(String t)
{
    title=t;
}
public double getPrice()
{
    return price;
}
public void setPrice(double p)
{
    price = p;
}
public int getQuantity()
{
    return quantity;
}
public void setQuantity(int q)
{
    quantity = q;
}

}

Answer 1

在 BookGUI 的构造函数中保存对 BookFile 实例的引用。然后，您可以通过 BookGUI 中的任何方法访问它。另外，您应该避免像 bkg 这样的短变量名称。使您的代码更难理解。

BookGUI.java

// ...
private final BookFile bookFile;

public BookGUI(BookFile bookFile)
{
    this.bookFile = bookFile;
    // ...

编辑

正如 @Majid L 所说，类型名称实际上应该以大写字母开头，因此 bookFile 应该是 BookFile