Scala 银行账户类扩展 - CheckingAccount 收取手续费

{"class":"BankAccount","initialBalance":"Double","balance":"Double","deposit":"Double","withdraw":"Double","CheckingAccount":"BankAccount","initialBalance":"Double","deposit":"Double","withdraw":"Double"} 在上述代码中，BankAccount类表示一个银行账户，CheckingAccount类是对BankAccount类的扩展，每次存款和取款都会收取1块钱的手续费。在CheckingAccount类中，通过使用super关键字调用BankAccount类的deposit和withdraw方法，并在其基础上减去1来实现手续费的收取。