[英]Java RandomAccessFile , Only finds the first entry
當我的程序從 randomaccessfile 中讀取時,它只會找到第一個文件或具有最低帳號的文件(這是一個銀行程序)之后,我收到了帶有讀取錯誤的 IO 異常
private RandomAccessFile input; // Random Aecess File input Stream
private Record data;
public static JFrame frame = new JFrame();
public CredRead() // Constructor CredRead created
{
// open the file
try {
// declare the output stream object and associate it to file
// file.dat
input = new RandomAccessFile("UnionDB.dat", "rw");
}
catch (IOException e) {
// if an error occurs display a message on the screen
System.err.println("File not opened properly\n " + e.toString());
// the program terminates due to error
System.exit(1);
}
data = new Record();
setPreferredSize(new Dimension(650, 400));
frame.setSize(getPreferredSize()); // Frame Size
frame.setLocationRelativeTo(null);
frame.setLayout(new GridLayout(7, 2)); // Grid Layout set
/* GUI Components */
frame.add(new Label("Enter Account Number and click Enter"));
account_num = new TextField();
frame.add(account_num);
account_num.addActionListener(this);
frame.add(new Label("First Name"));
first_name = new TextField(20);
first_name.setEditable(false);
frame.add(first_name);
frame.add(new Label("Last Name"));
last_name = new TextField(20);
last_name.setEditable(false);
frame.add(last_name);
frame.add(new Label("Available Funds"));
balance = new TextField(20);
balance.setEditable(false);
frame.add(balance);
frame.add(new Label("Overdraft Limit"));
overdraft = new TextField(20);
overdraft.setEditable(false);
frame.add(overdraft);
enter = new Button("Enter");
enter.addActionListener(this);
frame.add(enter);
done = new Button("Click to Exit");
done.addActionListener(this);
frame.add(done);
setVisible(true); // GUI components set as visible to the program
}
public void readRecord() {
DecimalFormat twoDigits = new DecimalFormat("0.00");
try {
do {
data.read(input);
} while (data.getAccount() == 0);
input.seek(
(long) ( data.getAccount()-1 ) * Record.size());
data.write( input );
account_num.setText(String.valueOf(data.getAccount()));
first_name.setText(data.getFirstName());
last_name.setText(data.getLastName());
balance.setText(String.valueOf(twoDigits.format(data.getBalance())));
overdraft.setText(String.valueOf(twoDigits.format(data.getOverdraft())));
}// end try
catch (EOFException eof) {
closeFile();
}
catch (IOException e) {
// if an error occurs display a message on the screen
System.err.println("Error during read from file\n " + e.toString());
// the program terminates due to error
// System.exit(1);
}
}
private void closeFile() {
try {
input.close();
// System.exit(1);
} catch (IOException e) {
// if an error occurs display a message on the screen
System.err.println("Error closing file\n " + e.toString());
// System.exit(1);
}
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == enter)
readRecord();
else if (e.getSource() == done)
frame.dispose();
else
frame.add(new TextField(" Account Not Found on Database "));
closeFile();
}
public static void main(String args[]) {
new CredRead();
}
}
我的猜測是
數據.getAccount() != 0
所以你的循環只執行一次,因為你是在 do ... while();
嘗試在您的代碼中添加一些調試並確保 data.getAccount() 等於什么。
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