检查错误 public class Test extends Base { public Test() { super(); } public static void main(String[] args) { Test t = new Test(); Test t2 = new Test("TestName"); } } class Base { String name; Base() { System.out.println("Base Constructor"); } Base(String name) { this.name = name; } }

这段代码有一个编译错误，因为在 Test 类中的第二个实例化语句 `Test t2 = new Test("TestName");` 中，Test 类没有定义一个接收 String 类型参数的构造函数。

如果想要解决这个问题，可以在 Test 类中添加一个接收 String 类型参数的构造函数，例如：

public Test(String name) {
    super(name);
}

这样就可以通过传递一个字符串参数来创建 Test 类的实例了。

相关问题

Look at the Account class Account.java and write a main method in a different class to briefly experiment with some instances of the Account class. o Using the Account class as a base class, write two derived classes called SavingsAccount and CurrentAccount. A SavingsAccount object, in addition to the attributes of an Account object, should have an interest variable and a method which adds interest to the account. A CurrentAccount object, in addition to the attributes of an Account object, should have an overdraft limit variable. Ensure that you have overridden methods of the Account class as necessary in both derived classes. o Now create a Bank class, an object of which contains an array of Account objects. Accounts in the array could be instances of the Account class, the SavingsAccount class, or the CurrentAccount class. Create some test accounts (some of each type). o Write an update method in the bank class. It iterates through each account, updating it in the following ways: Savings accounts get interest added (via the method you already wrote); CurrentAccounts get a letter sent if they are in overdraft. o The Bank class requires methods for opening and closing accounts, and for paying a dividend into each account.

Here is an implementation of the requested classes with a brief main method to test the Account class:

class Account {
    private String accountNumber;
    private double balance;

    public Account(String accountNumber, double balance) {
        this.accountNumber = accountNumber;
        this.balance = balance;
    }

    public void deposit(double amount) {
        this.balance += amount;
    }

    public void withdraw(double amount) {
        if (this.balance - amount < 0) {
            System.out.println("Insufficient funds.");
            return;
        }
        this.balance -= amount;
    }

    public void printBalance() {
        System.out.println("Account balance: " + this.balance);
    }
}

class SavingsAccount extends Account {
    private double interestRate;

    public SavingsAccount(String accountNumber, double balance, double interestRate) {
        super(accountNumber, balance);
        this.interestRate = interestRate;
    }

    public void addInterest() {
        double interest = this.getBalance() * this.interestRate;
        this.deposit(interest);
    }
}

class CurrentAccount extends Account {
    private double overdraftLimit;

    public CurrentAccount(String accountNumber, double balance, double overdraftLimit) {
        super(accountNumber, balance);
        this.overdraftLimit = overdraftLimit;
    }

    @Override
    public void withdraw(double amount) {
        if (this.getBalance() - amount < -overdraftLimit) {
            System.out.println("Overdraft limit exceeded.");
            return;
        }
        super.withdraw(amount);
    }
}

class Bank {
    private Account[] accounts;

    public Bank(Account[] accounts) {
        this.accounts = accounts;
    }

    public void update() {
        for (Account account : accounts) {
            if (account instanceof SavingsAccount) {
                ((SavingsAccount) account).addInterest();
            } else if (account instanceof CurrentAccount) {
                if (account.getBalance() < 0) {
                    System.out.println("Sending overdraft letter to account " + account.getAccountNumber());
                }
            }
        }
    }

    public void openAccount(Account account) {
        Account[] newAccounts = new Account[accounts.length + 1];
        System.arraycopy(accounts, 0, newAccounts, 0, accounts.length);
        newAccounts[accounts.length] = account;
        accounts = newAccounts;
    }

    public void closeAccount(Account account) {
        Account[] newAccounts = new Account[accounts.length - 1];
        int j = 0;
        for (int i = 0; i < accounts.length; i++) {
            if (accounts[i] != account) {
                newAccounts[j] = accounts[i];
                j++;
            }
        }
        accounts = newAccounts;
    }

    public void payDividend(double amount) {
        for (Account account : accounts) {
            account.deposit(amount);
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Account account1 = new Account("A001", 1000);
        SavingsAccount account2 = new SavingsAccount("A002", 2000, 0.01);
        CurrentAccount account3 = new CurrentAccount("A003", 5000, 1000);

        account1.deposit(500);
        account1.printBalance();
        account1.withdraw(2000);
        account1.printBalance();

        account2.addInterest();
        account2.printBalance();

        account3.withdraw(2000);
        account3.printBalance();
        account3.withdraw(5000);
        account3.printBalance();

        Account[] accounts = {account1, account2, account3};
        Bank bank = new Bank(accounts);

        bank.update();

        bank.openAccount(new Account("A004", 1500));
        bank.closeAccount(account1);

        bank.payDividend(100);
        bank.update();
    }
}

This code creates three accounts of different types, performs some transactions on them, creates a Bank object with an array of accounts, and calls some methods on the Bank object to update accounts, open and close accounts, and pay dividends.

java中怎么在测试类的main里输出子类里的tostring

在Java中，要在测试类的`main`方法里输出子类的`toString()`方法，你可以创建一个子类的对象并调用这个方法。首先，假设有一个基类`BaseClass`和一个子类`SubClass`，它们都实现了`toString()`方法。

public class BaseClass {
    // 省略具体内容，假设有一个成员变量或其他属性

    @Override
    public String toString() {
        return "BaseClass instance";
    }
}

public class SubClass extends BaseClass {
    // 如果有特定内容，可以添加额外的字段

    @Override
    public String toString() {
        return "SubClass instance with " + super.toString();
    }
}

public class TestClass {
    public static void main(String[] args) {
        SubClass subInstance = new SubClass(); // 创建子类的实例
        System.out.println(subInstance.toString()); // 输出子类的toString结果
    }
}

在这个例子中，当你运行`main`方法时，会打印出`SubClass instance with BaseClass instance`，因为子类覆盖了父类的`toString`方法，并且调用了`super.toString()`获取基础类的版本。