我一直在创建GUI，以存储小工具（例如手机和MP3）的详细信息。将这些小工具的一些对象存储到“数组列表”中，然后单击displayAll（）按钮后，它不会显示它们的值，而是显示Nulls和0。
我已经尽一切努力放弃了。
在下面，您将找到GUI类，然后是小工具超类和移动子类。
import java.util.ArrayList;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GadgetShop implements ActionListener
{
// instance variables - replace the example below with your own
private JTextField modelTextField;
private JTextField priceTextField;
private JTextField weightTextField;
private JTextField sizeTextField;
private JTextField initialCreditTextField;
private JTextField initialMemoryTextField;
private JTextField phoneNumberTextField;
private JTextField durationTextField;
private JTextField downloadSizeTextField;
private JTextField displayNumberTextField;
private JButton addMobileButton;
private JButton addMp3Button;
private JButton clearButton;
private JButton displayAllButton;
private JButton makeCallButton;
private JButton downloadMusicButton;
private JLabel modelLabel;
private JLabel priceLabel;
private JLabel weightLabel;
private JLabel sizeLabel;
private JLabel creditLabel;
private JLabel memoryLabel;
private JLabel phoneNumLabel;
private JLabel durationLabel;
private JLabel downloadLabel;
private JLabel dispNumLabel;
private JFrame frame;
private ArrayList<Gadget> gadgets;
private int myCredit;
private String theModel;
private String theSize;
private int theWeight;
private double thePrice;
private int theMemory;
/**
* The GUI is created in the constructor.
*/
public GadgetShop()
{
// initialise instance variables
gadgets = new ArrayList<Gadget>();
frame = new JFrame("The Gadget Shop");
Container contentPane = frame.getContentPane();
contentPane.setLayout(new GridLayout(7, 4));
JLabel modelLabel = new JLabel("Model:");
contentPane.add(modelLabel);
JLabel priceLabel = new JLabel("Price:");
contentPane.add(priceLabel);
JLabel weightLabel = new JLabel("Weight:");
contentPane.add(weightLabel);
JLabel sizeLabel = new JLabel("Size:");
contentPane.add(sizeLabel);
modelTextField = new JTextField(15);
contentPane.add(modelTextField);
priceTextField = new JTextField(15);
contentPane.add(priceTextField);
weightTextField = new JTextField(15);
contentPane.add(weightTextField);
sizeTextField = new JTextField(15);
contentPane.add(sizeTextField);
JLabel creditLabel = new JLabel("Credit:");
contentPane.add(creditLabel);
JLabel memoryLabel = new JLabel("Memory:");
contentPane.add(memoryLabel);
addMobileButton = new JButton("Add Mobile");
contentPane.add(addMobileButton);
addMobileButton.addActionListener(this);
addMp3Button = new JButton("Add MP3");
contentPane.add(addMp3Button);
addMp3Button.addActionListener(this);
initialCreditTextField = new JTextField(15);
contentPane.add(initialCreditTextField);
initialMemoryTextField = new JTextField(15);
contentPane.add(initialMemoryTextField);
clearButton = new JButton("Clear");
contentPane.add(clearButton);
clearButton.addActionListener(this);
displayAllButton = new JButton("Display All");
contentPane.add(displayAllButton);
displayAllButton.addActionListener(this);
JLabel phoneNumLabel = new JLabel("Phone No:");
contentPane.add(phoneNumLabel);
JLabel durationLabel = new JLabel("Duration:");
contentPane.add(durationLabel);
JLabel downloadLabel = new JLabel("Download:");
contentPane.add(downloadLabel);
JLabel dispNumLabel = new JLabel("Display Number:");
contentPane.add(dispNumLabel);
phoneNumberTextField = new JTextField(15);
contentPane.add(phoneNumberTextField);
durationTextField = new JTextField(15);
contentPane.add(durationTextField);
downloadSizeTextField = new JTextField(15);
contentPane.add(downloadSizeTextField);
displayNumberTextField = new JTextField(15);
contentPane.add(displayNumberTextField);
makeCallButton = new JButton("Make A Call");
contentPane.add(makeCallButton);
makeCallButton.addActionListener(this);
downloadMusicButton = new JButton("Download Music");
contentPane.add(downloadMusicButton);
downloadMusicButton.addActionListener(this);
frame.pack();
frame.setVisible(true);
}
/**
* The main method allows the program to be run without BlueJ.
*/
public static void main(String[] args)
{
GadgetShop calculator = new GadgetShop();
}
/**
* Find which button triggered the event and call the appropriate method.
*/
public void actionPerformed(ActionEvent event)
{
String command = event.getActionCommand();
if (command.equals("Add Mobile")) {
addMobile();
}
if (command.equals("Add MP3")) {
addMp3();
}
if (command.equals("Display All")) {
displayAll();
}
if (command.equals("Make A Call")) {
makeCall();
}
if (command.equals("Download Music")) {
downloadMusic();
}
if (command.equals("Clear")) {
clear();
}
}
public String getModel()
{
String model
= modelTextField.getText();
return model;
}
public String getSize()
{
String size
= sizeTextField.getText();
return size;
}
public String getNumber()
{
String phoneNumber
= phoneNumberTextField.getText();
return phoneNumber;
}
public int getWeight()
{
int weight
= Integer.parseInt(weightTextField.getText());
return weight;
}
public double getPrice()
{
double price
= Double.parseDouble(priceTextField.getText());
return price;
}
public int getCredit()
{
int credit
= Integer.parseInt(initialCreditTextField.getText());
return credit;
}
public int getMemory()
{
int memory
= Integer.parseInt(initialMemoryTextField.getText());
return memory;
}
public int getDuration()
{
int duration
= Integer.parseInt(durationTextField.getText());
return duration;
}
public int getDownloadSize()
{
int downloadSize
= Integer.parseInt(downloadSizeTextField.getText());
return downloadSize;
}
public int numberOfGadgets()
{
return gadgets.size();
}
public int getDisplayNumber()
{
int displayNumber = -1;
try {
displayNumber
= Integer.parseInt(displayNumberTextField.getText());
if(displayNumber < 0) {
JOptionPane.showMessageDialog(frame,
"Please enter a positive number");
}
else if(displayNumber > numberOfGadgets()) {
JOptionPane.showMessageDialog(frame,
"Please enter a number in the correct range");
}
}
catch(NumberFormatException exception) {
}
return displayNumber;
}
下面是创建，存储和显示ArrayList对象的方法
public void addMobile()
{
Mobile mobile = new Mobile(myCredit, theModel, theSize, theWeight, thePrice);
gadgets.add(mobile);
}
public void addMp3()
{
Gadget mp3 = new MP3(theMemory, theModel, theSize, theWeight, thePrice);
gadgets.add(mp3);
}
public void displayAll()
{
for(Gadget gadget : gadgets) {
gadget.print();
System.out.println(); // empty line between items
}
}
public void makeCall()
{
//Nothing here atm
}
public void downloadMusic()
{
//Nothing here atm
}
public void clear()
{
modelTextField.setText("");
sizeTextField.setText("");
phoneNumberTextField.setText("");
weightTextField.setText("");
priceTextField.setText("");
initialCreditTextField.setText("");
initialMemoryTextField.setText("");
durationTextField.setText("");
downloadSizeTextField.setText("");
displayNumberTextField.setText("");
}
}
下面是Mobile子类
public class Mobile extends Gadget
{
// instance variables - replace the example below with your own
private int credit;
/**
* Constructor for objects of class Mobile
*/
public Mobile(int myCredit, String theModel, String theSize, int theWeight, double thePrice)
{
// initialise instance variables
super(theModel, theSize, theWeight, thePrice);
credit = myCredit;
}
/**
* This is an accessor method that allows the user to view the balance of credit remaining in the mobile phone.
*/
public int getCredit()
{
return credit;
}
/**
* This is a mutator method that allows the user to top up the credit on their mobile phone.
*/
public void addCredit(int topUp)
{
if (topUp > 0) {
credit = credit + topUp;
}
else {
System.out.println("Please enter an amount greater than 0.");
}
}
/**
* This is a mutator method that allows the user to enter the phone number that they'd like to call and the duration of that call in minutes.
*/
public void makeCall(String number, int minutes)
{
if (credit >= minutes) {
System.out.println("You called this number: " + number + " for the duration of: " + minutes + " minute/s.");
credit = credit - minutes;
System.out.println(" ");
System.out.println("You now have " + credit + " minutes of calling credit remaining in your balance.");
}
else {
System.out.println("Sorry, but you have an insufficient amount of credit to make this call.");
}
}
/**
* This output method displays certain specifications of the mobile device such as the: Model, size, weight and price. The amount of credit remaining in the mobile is also displayed.
*/
public void print()
{
super.print();
System.out.println("You have " + credit + " minutes of credit remaining.");
}
}
以下是小工具超类
public class Gadget
{
// instance variables
private String model;
private String size;
private int weight;
private double price;
/**
* Constructor for objects of class Gadget
*/
public Gadget(String theModel, String theSize, int theWeight, double thePrice)
{
// initialised instance variables
model = theModel;
size = theSize;
weight = theWeight;
price = thePrice;
}
/**
* This is an accessor method that returns the model number of the gadget.
*/
public String getModel()
{
return model;
}
/**
* This is an accessor method that returns the size of the gadget.
*/
public String getSize()
{
return size;
}
/**
* This is an accessor method that returns the weight of the gadget.
*/
public int getWeight()
{
return weight;
}
/**
* This is an accessor method that returns the price of the gadget.
*/
public double getPrice()
{
return price;
}
/**
* This is an output method that displays the model, size, weight and price of an object to the user.
*/
public void print()
{
System.out.println("Model: " + model);
System.out.println("Size: " + size);
System.out.println("Weight: " + weight);
System.out.println("Price: " + price);
}
}
非常感谢我能正确显示详细信息而获得的所有帮助。谢谢。
答案 0 :(得分：0)
您在代码中犯了一个主要错误。根据您的代码，addMobile方法必须为
public void addMobile()
{
Mobile mobile = new Mobile(getCredit(), getModel(), getSize(), getWeight(), getPrice());
gadgets.add(mobile);
}
myCredit,theModel,theSize,theWeight,thePrice,theMemory的值从未在代码中的任何位置分配。已经编写了各种get方法来获取TextField的值，但从未调用过这些方法。
addMP3方法也是如此。确保使用正确的值调用Mobile和MP3的构造函数。其余代码没有任何问题。