所以我试图在我的AccountWithException类中调用我的toString方法来打印文件中包含的用户输入，但由于某种原因我无法破解它为什么不打印。我试图做System.out.println（pw.toString（））..只是为了让我不断打印内存位置。最初我只是回读文件，但我的教师指定了这个：“使用重载的toString方法输出到控制台和文件（通过PrintWriter）”我使用重载的toString作为我的对象，但无法找到我的文件。在我的代码中是否有一些我忽略的东西或者这是一个简单的Sysout.println（）语句？已添加要求。
1。）提示用户输出文件名。为文本输出创建一个文件。
2。）如果文件存在则提示用户输入新文件名。在输入有效的非现有文件名并打开文件进行输出之前，请勿继续。
3。）提示用户输入名字，姓氏，余额，（账户ID和年利率可以是常数）
4.。）创建包含用户指定数据的AccountWithExceptionObject。
5.如果对象中存在有效数据：将对象信息输出到显示器AS以及打开的输出文件。输出数据时使用重载的toString（）方法。如果存在无效数据（＆lt; 0），则抛出自定义InvalidBalanceException。
6。）使用finally块确保输出文件已正确关闭。
import java.util.Scanner;
import java.io.File;
//import java.io.FileNotFoundException;
//import java.io.IOException;
import java.io.PrintWriter;
//import java.io.FileReader;
//import java.io.BufferedReader;
public class TestAccountWithException {
public static void main(String[] args) throws InvalidBalanceException, FileNotFoundException, IOException {
// variable declaration
String fileName;
String firstName;
String lastName;
double balance;
int id = 1122;
final double RATE = 4.50;
Scanner input = new Scanner(System.in);
System.out.print("Please enter a file name: ");
fileName = input.next();
File fw = new File(fileName + ".txt");
// while loop to check if file already exists
while (fw.exists()) {
System.out.print("File already exists, enter valid file name: ");
fileName = input.next();
fw = new File(fileName + ".txt");
}
System.out.print("Enter your first name: ");
firstName = input.next();
System.out.print("Enter your last name: ");
lastName = input.next();
// concatanate full/last name
String fullName = firstName.concat(" " + lastName);
System.out.print("Input beginnning balance: ");
balance = input.nextDouble();
PrintWriter pw = null;
// pass object to printwriter and pw to write to the file
pw = new PrintWriter(fw);
// print to created file
pw.println(firstName);
pw.println(lastName);
pw.println(balance);
pw.println(id);
pw.println(RATE);
String line = null;
try {
// pass user input to object
AccountWithException acctException = new AccountWithException(fullName, balance, id, RATE);
System.out.println(acctException.toString());
// create the object
//FileReader fr = new FileReader(fileName + ".txt");
// pass to buffered reader and use its preset commands for alteration to file
//BufferedReader br = new BufferedReader(fr);
//System.out.println("Text file opened and reading...");
// read in lines from file
// while ((line = br.readLine()) != null) {
//System.out.println(line);
//}
// close buffered reader
//br.close();
// custom exception if balance < 0
} catch (InvalidBalanceException e) {
System.out.println(e.getMessage());
//} catch (FileNotFoundException e) {
//System.out.println("File not found" + fileName);
//} catch (IOException e) {
//System.out.println(e.getMessage());
} finally {
System.out.println("Text file closing...");
pw.close();
}
} // end main
} // end class
public class AccountWithException {
private int id;
private double balance;
private static double annualInterestRate;
private java.util.Date dateCreated;
// CRE additions for lab assignment
private String name;
// no-arg constructor to create default account
public AccountWithException() {
this.dateCreated = new java.util.Date();
}
//constructor for test account with exception that takes in arguments
public AccountWithException(String newName, double newBalance, int newId, double newRate) throws InvalidBalanceException {
setName(newName);
setBalance(newBalance);
setId(newId);
setAnnualInterestRate(newRate);
this.dateCreated = new java.util.Date();
}
/* // constructor for test account with exception that takes in arguments
public AccountWithException(String newName, double newBalance, int newId, double newRate) {
this.name = newName;
this.balance = newBalance;
this.id = newId;
AccountWithException.annualInterestRate = newRate;
this.dateCreated = new java.util.Date();
} */
// accessor methods
public int getId() {
return this.id;
}
public double getBalance() {
return this.balance;
}
public static double getAnnualInterestRate() {
return annualInterestRate;
}
public double getMonthlyInterest() {
return this.balance * (this.annualInterestRate / 1200);
}
public java.util.Date getDateCreated() {
return this.dateCreated;
}
public String getName() {
return this.name;
}
// mutator methods
public void setId(int newId) {
this.id = newId;
}
public void setBalance(double newBalance) throws InvalidBalanceException {
if(newBalance >= 0) {
this.balance = newBalance;
}
else {
throw new InvalidBalanceException(newBalance);
}
}
public static void setAnnualInterestRate(double newAnnualInterestRate) {
annualInterestRate = newAnnualInterestRate;
}
public void setName(String newName) {
this.name = newName;
}
// balance modification methods
public void withdraw(double amount) {
this.balance -= amount;
}
public void deposit(double amount) {
this.balance += amount;
}
// override of Object method
public String toString() {
// return string with formatted data
// left-align 20 character column and right-align 15 character column
return String.format("%-20s%15d\n%-20s%15tD\n%-20s%15s\n%-20s%15.2f%%\n%-20s%,15.2f\n",
"ID:", this.id,
"Created:", this.dateCreated,
"Owner:", this.name,
"Annual Rate:", this.annualInterestRate,
"Balance:", this.balance);
}
}
public class InvalidBalanceException extends Exception {
private double balance;
public InvalidBalanceException(double balance) {
// exceptions constructor can take a string as a message
super("Invalid Balance " + balance);
this.balance = balance;
}
public double getBalance() {
return balance;
}
}
答案 0 :(得分：0)
尝试在你的tostring方法上打一个@Override。
// override of Object method
@Override
public String toString() {
// return string with formatted data
// left-align 20 character column and right-align 15 character column
return String.format("%-20s%15d\n%-20s%15tD\n%-20s%15s\n%-20s%15.2f%%\n%-20s%,15.2f\n",
"ID:", this.id,
"Created:", this.dateCreated,
"Owner:", this.name,
"Annual Rate:", this.annualInterestRate,
"Balance:", this.balance);
}
}
此外，在命名类时，如果它们抛出异常，则不应对其进行“WithException”。这个班应该只是“帐户”。