Java自定义异常类

Question

我在创建自己的异常类时遇到了一个相当微不足道的问题。我已经扩展了它，并尝试在构造函数中接收 double 值，但我不断收到错误。

银行帐户@withdraw内部出现错误“不兼容的类型:InsufficientFundsException无法转换为可抛出”

异常类:

    public class InsufficientFundsException extends RuntimeException {

    private double shortFall;   

    public InsufficientFundsException(double a) {
        super("Insufficient funds");
        shortFall = a;
    }

    public double getAmount() { return shortFall; }

}

银行账户类别:

public class BankAccount {

    private int accountNumber;
    private double balance;

    // Class constructor
    public BankAccount(int account) {
        accountNumber = account;
        balance = 0.0;
    }

    public int getAccountNumber() {

        return accountNumber;
    }

    public double getBalance()
    {
        return balance;
    }

    public void deposit(double b) {
        balance += b;
    }

    public void withdraw(double w) throws InsufficientFundsException {

        double difference;
        if(w > balance) {
            difference = w - balance;           
        } else {
            balance -= w;   
        }
    }

我想提款，除非提款金额大于当前余额。在这种情况下我想抛出异常。我还尝试在 if 内部抛出异常，但我得到:

类 InsufficientFundsException 中的构造函数 InsufficientFundsException 不能应用于给定类型； 必需:无参数 发现:双 原因:实际参数列表和形式参数列表的长度不同

 public void withdraw(double w)  {

        double difference;
        if(w > balance) {
            difference = w - balance; 
            Exception ex =  new InsufficientFundsException(difference);
        } else {
            balance -= w;   
        }
    }

不过我只有一个构造函数。如有任何建议或帮助，我们将不胜感激。

Answer 1

你尝试过吗...

throw new InsufficientFundsException(difference);

代替

Exception ex =  new InsufficientFundsException(difference);

这通常是抛出异常的方式。

更新了代码片段...

public void withdraw(double w) throws InsufficientFundsException {

    double difference;
    if(w > balance) {
        difference = w - balance;    
        throw new InsufficientFundsException(difference);
    } else {
        balance -= w;   
    }
}

与...一起跑

public static void main(String[] args){
    BankAccount account = new BankAccount(1);
    account.withdraw(5.0);
}

得到了......

Exception in thread "main" com.misc.help.InsufficientFundsException:     Insufficient funds
at com.misc.help.BankAccount.withdraw(BankAccount.java:32)
at com.misc.help.BankAccount.main(BankAccount.java:40)