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我已經清理字符串平等.equals方法，改變了ContactsCollection初始化：
public static ArrayList<Contact> contactList = new ArrayList<Contact>();
我也改變了執行的操作方法希望「顯示聯繫人」能顯示多個聯繫人。
if (contactInput.equals("Display contacts"))
{
ContactsCollection.read();
for (int i = 0; i < contactList.size(); i++)
{
contact = (Contact)contactList.get(i);
for (int j =0; j < contactList.size(); j++)
{
textArea.append(contact.getName() + "," + contact.getNumber() + "\n");
}
}
}
最終將編寫.dat文件，但不包含任何通過GUI添加的數據。
編輯完
我寫一個模擬手機圖形用戶界面，作爲一個非常基本的聯繫人管理。還有其他幾個類沒有處理按預期工作的ArrayList。
當試圖將聯繫人添加到該文件I在ContactsCollection類的線13接收一個零指示字例外：
for (int i = 0; i < contactList.size(); i++)
和線93的觸點（GUI）類：
contactList.add(contact);
我有一種感覺，我編寫聯繫人和ContactsCollection類時做了錯誤。我希望程序運行如下：用戶點擊添加聯繫人並輸入成爲對象聯繫人的信息，並添加到contactList ArrayList中並寫入（序列化）到文件「contactList.dat」。當用戶點擊顯示聯繫人時，文件被讀入並且每個聯繫人被顯示在GUI中。
我認爲我設置ArrayList的方式有幾個問題，但我認爲我非常接近讓程序按我的希望運行。任何幫助是極大的讚賞！
聯繫人類：
import java.util.*;
import java.io.*;
public class Contact implements Serializable
{
public static final long serialVersionUID = 42L;
public String name, number;
Contact()
{
name = "No name";
number = "No number";
}
Contact (String theName, String theNumber)
{
this.name = theName;
this.number = theNumber;
}
public void setName(String aName)
{
this.name = aName;
}
public void setNumber(String aNumber)
{
this.number =aNumber;
}
public String getName()
{
return name;
}
public String getNumber()
{
return number;
}
public String toString()
{
return name + ": " + number;
}
public boolean equals(Contact other)
{
if (name.equals(other.getName()) && number.equals(other.getNumber()))
{
return(true);
}
else
{
return(false);
}
}
}
聯繫人Collection類
import java.io.*;
import java.util.*;
class ContactsCollection
{
public static ArrayList<Contact> contactList;
public static void write()
{
try
{
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("contactList.dat"));
for (int i = 0; i < contactList.size(); i++)
{
out.writeObject(contactList.get(i));
}
out.close();
}
catch(IOException e)
{
e.printStackTrace();
}
}
public static void read()
{
contactList = new ArrayList<Contact>();
try
{
ObjectInputStream in = new ObjectInputStream(new FileInputStream("contactList.dat"));
Contact temp;
while (in.available()!=0)
{
temp = (Contact)in.readObject();
contactList.add(temp);
}
in.close();
}
catch(FileNotFoundException e)
{
e.printStackTrace();
}
catch(IOException e)
{
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
e.printStackTrace();
}
}
}
聯繫人（GUI）類
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.Timer;
import java.util.*;
class Contacts extends JFrame implements ActionListener, WindowListener
{
public static final int WIDTH = 400;
public static final int HEIGHT = 600;
public static final int SMALL_WIDTH = 200;
public static final int SMALL_HEIGHT = 100;
private static final Dimension stdBtn = new Dimension(150, 50);
JPanel centerPanel, northPanel, southPanel;
ImageIcon icon;
JLabel picture;
JButton addContact, displayContacts;
JScrollPane scroll;
JTextArea textArea;
Clock clock;
Background background;
Contact contact;
ArrayList<Contact> contactList;
public Contacts()
{
super("Contacts");
this.setLayout(new BorderLayout());
this.setSize(WIDTH, HEIGHT);
this.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
addWindowListener(this);
this.setLocationRelativeTo(null);
centerPanel = new JPanel();
northPanel = new JPanel();
southPanel = new JPanel();
centerPanel.setBackground(Color.BLACK);
southPanel.setBackground(Color.BLACK);
clock = new Clock();
northPanel.add(clock);
icon = new ImageIcon("ContactsBackground.jpg");
picture = new JLabel(icon);
centerPanel.add(picture);
textArea = new JTextArea("", 10, 30);
textArea.setEditable(false);
JScrollPane scroll = new JScrollPane(textArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
centerPanel.add(scroll);
JButton displayContacts = new JButton("Display contacts");
displayContacts.addActionListener(this);
southPanel.add(displayContacts);
JButton addContact = new JButton("Add contact");
addContact.addActionListener(this);
southPanel.add(addContact);
this.add(northPanel, BorderLayout.NORTH);
this.add(centerPanel, BorderLayout.CENTER);
this.add(southPanel, BorderLayout.SOUTH);
setResizable(false);
}
public void actionPerformed(ActionEvent e)
{
contactList = new ArrayList<Contact>();
JButton source = (JButton)e.getSource();
String contactInput = source.getText();
if (contactInput == "Display contacts")
{
ContactsCollection.read();
for (int i = 0; i < contactList.size(); i++)
{
contact = (Contact)contactList.get(i);
textArea.setText(contact.getName() + "," + contact.getNumber() + "\n");
}
}
if (contactInput == "Add contact")
{
String name = JOptionPane.showInputDialog(null, "Enter Name");
String number = JOptionPane.showInputDialog(null, "Enter Number");
contact = new Contact(name, number);
contactList.add(contact);
ContactsCollection.write();
}
}
public void windowOpened(WindowEvent e)
{}
public void windowClosing(WindowEvent e)
{
this.setVisible(false);
background = new Background();
background.setVisible(true);
}
public void windowClosed(WindowEvent e)
{}
public void windowIconified(WindowEvent e)
{}
public void windowDeiconified(WindowEvent e)
{}
public void windowActivated(WindowEvent e)
{}
public void windowDeactivated(WindowEvent e)
{}
}
這是太多的代碼。 13號線在哪裏？ – Ankit