0
這是一個錯誤消息，隨着我嘗試在我的程序中顯示結果時不斷出現。我需要幫助瞭解錯誤消息
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at AddressBookIO.getEntriesString(AddressBookIO.java:38)
at AddressBookEntryApp.main(AddressBookEntryApp.java:42)
我幾乎可以肯定我的代碼是正確的。除了顯示我的結果之外，我的程序會完成它想要做的一切。 「」main「java.lang.ArrayIndexOutOfBoundsException：0」是使我困惑的部分。
繼承人爲AddressBookIO.java的代碼，並AddressBookEntryApp
import java.io.*;
public class AddressBookIO
{
private static File addressBookFile = new File("address_book.txt");
private static final String FIELD_SEP = "\t";
private static final int COL_WIDTH = 20;
// use this method to return a string that displays
// all entries in the address_book.txt file
public static String getEntriesString()
{
BufferedReader in = null;
try
{
checkFile();
in = new BufferedReader(
new FileReader(addressBookFile));
// define the string and set a header
String entriesString = "";
entriesString = padWithSpaces("Name", COL_WIDTH)
+ padWithSpaces("Email", COL_WIDTH)
+ padWithSpaces("Phone", COL_WIDTH)
+ "\n";
entriesString += padWithSpaces("------------------", COL_WIDTH)
+ padWithSpaces("------------------", COL_WIDTH)
+ padWithSpaces("------------------", COL_WIDTH)
+ "\n";
// append each line in the file to the entriesString
String line = in.readLine();
while(line != null)
{
String[] columns = line.split(FIELD_SEP);
String name = columns[0];
String emailAddress = columns[1];
String phoneNumber = columns[2];
entriesString +=
padWithSpaces(name, COL_WIDTH) +
padWithSpaces(emailAddress, COL_WIDTH) +
padWithSpaces(phoneNumber, COL_WIDTH) +
"\n";
line = in.readLine();
}
return entriesString;
}
catch(IOException ioe)
{
ioe.printStackTrace();
return null;
}
finally
{
close(in);
}
}
// use this method to append an address book entry
// to the end of the address_book.txt file
public static boolean saveEntry(AddressBookEntry entry)
{
PrintWriter out = null;
try
{
checkFile();
// open output stream for appending
out = new PrintWriter(
new BufferedWriter(
new FileWriter(addressBookFile, true)));
// write all entry to the end of the file
out.print(entry.getName() + FIELD_SEP);
out.print(entry.getEmailAddress() + FIELD_SEP);
out.print(entry.getPhoneNumber() + FIELD_SEP);
out.println();
}
catch(IOException ioe)
{
ioe.printStackTrace();
return false;
}
finally
{
close(out);
}
return true;
}
// a private method that creates a blank file if the file doesn't already exist
private static void checkFile() throws IOException
{
// if the file doesn't exist, create it
if (!addressBookFile.exists())
addressBookFile.createNewFile();
}
// a private method that closes the I/O stream
private static void close(Closeable stream)
{
try
{
if (stream != null)
stream.close();
}
catch(IOException ioe)
{
ioe.printStackTrace();
}
}
// a private method that is used to set the width of a column
private static String padWithSpaces(String s, int length)
{
if (s.length() < length)
{
StringBuilder sb = new StringBuilder(s);
while(sb.length() < length)
{
sb.append(" ");
}
return sb.toString();
}
else
{
return s.substring(0, length);
}
}
}
而且
import java.util.Scanner;
public class AddressBookEntryApp
{
public static void main(String args[])
{
// display a welcome message
System.out.println("Welcome to the Address Book application");
System.out.println();
Scanner sc = new Scanner(System.in);
int menuNumber = 0;
while (menuNumber != 3)
{
// display menu
System.out.println("1 - List entries");
System.out.println("2 - Add entry");
System.out.println("3 - Exit\n");
// get input from user
menuNumber = Validator.getIntWithinRange(sc, "Enter menu number: ", 0, 4);
System.out.println();
switch (menuNumber)
{
case 1:
{
String entriesString = AddressBookIO.getEntriesString();
System.out.println(entriesString);
break;
}
case 2:
{
// get data from user
String name = Validator.getRequiredString(sc, "Enter name: ");
String emailAddress = Validator.getRequiredString(sc, "Enter email address: ");
String phoneNumber = Validator.getRequiredString(sc, "Enter phone number: ");
// create AddressBookEntry object and fill with data
AddressBookEntry entry = new AddressBookEntry();
entry.setName(name);
entry.setEmailAddress(emailAddress);
entry.setPhoneNumber(phoneNumber);
AddressBookIO.saveEntry(entry);
System.out.println();
System.out.println("This entry has been saved.\n");
break;
}
case 3:
{
System.out.println("Goodbye.\n");
break;
}
}
}
}
}
請發佈您的（相關）代碼。 – 2012-03-09 05:10:36
「我幾乎可以肯定我的代碼是正確的」 - >它不是，因此是錯誤消息。相信你的編譯器。 – JRL 2012-03-09 05:11:45
我相信它，我只是因爲它而受到傷害。 – 2012-03-09 05:26:16