我制作了一个联系人列表，我的代码编译并运行，当您添加联系人、键入或电子邮件或电话时，它应该向您读取它们，我遇到的问题是当我添加联系人并按下一个或上一个时，首先或者最后它没有读取姓名联系人，但它读取了其他所有内容......它是否必须对间距做一些事情？这就是我所拥有的......谢谢
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class ContactSystem extends JFrame{
//Specify the size of five string fields in the record
final static int NAME_SIZE = 32;
final static int TYPE_SIZE = 32;
final static int CITY_SIZE = 20;
final static int PHONE_SIZE = 15;
final static int EMAIL_SIZE = 15;
final static int RECORD_SIZE =
(NAME_SIZE + TYPE_SIZE + CITY_SIZE + PHONE_SIZE + EMAIL_SIZE);
//access contact.dat using RandomAccessFile
private RandomAccessFile raf;
//Text Fields
private JTextField jbtName = new JTextField(NAME_SIZE);
private JTextField jbtType = new JTextField(TYPE_SIZE);
private JTextField jbtCity = new JTextField(CITY_SIZE);
private JTextField jbtPhone = new JTextField(PHONE_SIZE);
private JTextField jbtEmail = new JTextField(EMAIL_SIZE);
//Buttons
private JButton jbtAdd = new JButton("Add");
private JButton jbtFirst = new JButton("First");
private JButton jbtNext = new JButton("Next");
private JButton jbtPrevious = new JButton("Previous");
private JButton jbtLast = new JButton("Last");
public ContactSystem(){
//open or create a random access file
try {
raf = new RandomAccessFile("contact.txt", "rw");
}
catch(IOException ex) {
System.out.print("Error: " + ex);
System.exit(0);
}
//Panel p1 for holding labels Name , Type, Email or phone
JPanel p1 = new JPanel();
p1.setLayout(new GridLayout(3,1));
p1.add(new JLabel("Name Contact"));
p1.add(new JLabel("Email Address"));
p1.add(new JLabel("Type of Contact"));
//Panel jpPhone for holding Phone
JPanel jpPhone = new JPanel();
jpPhone.setLayout(new BorderLayout());
jpPhone.add(new JLabel("Phone"), BorderLayout.WEST);
jpPhone.add(jbtPhone, BorderLayout.CENTER);
//Panel jpEmail for holding Phone
JPanel jpEmail = new JPanel();
jpEmail.setLayout(new BorderLayout());
jpEmail.add(new JLabel("Phone"), BorderLayout.WEST);
jpEmail.add(jbtEmail, BorderLayout.CENTER);
// Panel p2 for holding jpPhone and jpEmail
JPanel p2 = new JPanel();
p2.setLayout(new BorderLayout());
p2.add(jpPhone, BorderLayout.WEST);
p2.add(jpPhone, BorderLayout.CENTER);
JPanel p3 = new JPanel();
p3.setLayout(new BorderLayout());
p3.add(jbtCity, BorderLayout.CENTER);
p3.add(p2, BorderLayout.EAST);
//panel p4 for holding jtfName, jtfType, and p3
JPanel p4 = new JPanel();
p4.setLayout(new GridLayout(3,1));
p4.add(jbtName);
p4.add(jbtType);
p4.add(p3);
//place p1 and p4 into jpContact
JPanel jpContact = new JPanel(new BorderLayout());
jpContact.add(p1, BorderLayout.WEST);
jpContact.add(p4, BorderLayout.CENTER);
//set panel with line border
jpContact.setBorder(new BevelBorder(BevelBorder.RAISED));
//add buttons to a panel
JPanel jpButton = new JPanel();
jpButton.add(jbtAdd);
jpButton.add(jbtFirst);
jpButton.add(jbtNext);
jpButton.add(jbtPrevious);
jpButton.add(jbtLast);
//add jpContact and jpButton to the frame
add(jpContact, BorderLayout.CENTER);
add(jpButton, BorderLayout.SOUTH);
jbtAdd.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
writeContact();
}
});
jbtFirst.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
if (raf.length() > 0) readContact(0);
}
catch(IOException ex){
ex.printStackTrace();
}
}
});
jbtNext.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
try {
long currentPosition = raf.getFilePointer();
if (currentPosition < raf.length())
readContact(currentPosition);
}
catch (IOException ex) {
ex.printStackTrace();
}
}
});
jbtPrevious.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
long currentPosition = raf.getFilePointer();
if(currentPosition - 2 * RECORD_SIZE > 0)
//why 2 * 2 * RECORD_SIZE? see the the follow-up remarks
readContact(currentPosition - 2 * 2 * RECORD_SIZE);
else
readContact(0);
}
catch(IOException ex){
ex.printStackTrace();
}
}
});
jbtLast.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
long lastPosition = raf.length();
if(lastPosition > 0)
//why 2 * RECORD_SIZE? see the follow up remarks
readContact(lastPosition - 2 * RECORD_SIZE);
}
catch (IOException ex) {
ex.printStackTrace();
}
}
});
try {
if (raf.length() > 0) readContact(0);
}
catch (IOException ex) {
ex.printStackTrace();
}
}
//write a record at the end of file
public void writeContact() {
try {
raf.seek(raf.length());
FixedLengthStringIO.writeFixedLengthString(
jbtName.getText(), NAME_SIZE, raf);
FixedLengthStringIO.writeFixedLengthString(
jbtType.getText(), TYPE_SIZE, raf);
FixedLengthStringIO.writeFixedLengthString(
jbtCity.getText(), CITY_SIZE, raf);
FixedLengthStringIO.writeFixedLengthString(
jbtPhone.getText(), PHONE_SIZE, raf);
FixedLengthStringIO.writeFixedLengthString(
jbtEmail.getText(), EMAIL_SIZE, raf);
}
catch (IOException ex) {
ex.printStackTrace();
}
}
//read a contact at the specific position
public void readContact(long position) throws IOException{
raf.seek(position);
String name = FixedLengthStringIO.readFixedLengthString(
NAME_SIZE, raf);
String type = FixedLengthStringIO.readFixedLengthString(
TYPE_SIZE, raf);
String city = FixedLengthStringIO.readFixedLengthString(
CITY_SIZE, raf);
String phone = FixedLengthStringIO.readFixedLengthString(
PHONE_SIZE, raf);
String email = FixedLengthStringIO.readFixedLengthString(
EMAIL_SIZE, raf);
jbtName.setText(name);
jbtType.setText(type);
jbtCity.setText(city);
jbtName.setText(phone);
jbtName.setText(email);
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ContactSystem frame = new ContactSystem();
frame.pack();
frame.setTitle("Contact System");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
固定长度字符串IO类
import java.io.*;
public class FixedLengthStringIO {
//read fixed number of characters from datainput stream
public static String readFixedLengthString(int size,
DataInput in) throws IOException {
//declare an array of characters
char[] chars = new char[size];
//read fixed number of characters to the array
for(int i = 0; i < size; i++)
chars[i] = in.readChar();
return new String (chars);
}
//write fixed number of characters to a dataoutput stream
public static void writeFixedLengthString(String s, int size,
DataOutput out) throws IOException {
char[] chars = new char[size];
//fill an array of characters from the string
s.getChars(0, Math.min(s.length(), size), chars, 0);
//fill in blank characters in the rest of the array
for (int i = Math.min(s.length(), size); i < chars.length; i++)
chars[i] = ' ';
//create and write a new string padded with blank characters
out.writeChars(new String(chars));
}
}
这是我在列表中输入联系人姓名、类型、电子邮件等的时候
当我按下一个或上一个，或第一个或最后一个时，它不会读取名称..
