Question

我有一个SavingsAccount对象，并且试图使用我的函数来操纵帐户的余额。现在我没有错误但没有输出。我感觉自己做错了什么，我不太了解如何在对象上调用函数。

如果我尝试打印其中一个帐户的输出，则会得到一个内存地址。

我在进行调整时遇到各种不同的错误，并且最终没有错误。但是仍然没有输出，恐怕我弄错了，它只是个bug，而且我没有以正确的方式调用我的函数，否则我的构造函数没有被编码为它的意图。

public class SavingsAccount {
  // Class
  int balance;
  int amountToDeposit;
  int amountToWithdraw;

  //Constructor
  public SavingsAccount(int initialBalance, int deposit, int withdraw){
    balance = initialBalance;
    amountToDeposit = deposit;
    amountToWithdraw = withdraw;
  }

  //Functions thats I wanna call

  // Setting balance
    public void checkBalance() {
        System.out.println("Hello!");
        System.out.println("Your balance is " + balance);
    }

  // Depositing amounts 
    public void deposit(int amountToDeposit) {
        balance = balance + amountToDeposit;
        System.out.println("You just deposited" + amountToDeposit);
  }

  // Withdrawing amounts
    public int withdraw(int amountToWithdraw) {
        balance = balance - amountToWithdraw;
        System.out.println("You just withdrew" + amountToWithdraw);

      return amountToWithdraw;
  }


  // Main
  public static void main(String[] args){
    //Setting values, balance, deposit, withdraw.
    SavingsAccount savings = new SavingsAccount(2000, 100, 2000);
    SavingsAccount test = new SavingsAccount(5000, 200, 100);


    //Check balance
     System.out.println(test); // Will give a memory adress
  }       
}

我想在制作的对象上使用我的函数并打印结果。

感谢阅读。

Answer 1

我感觉自己做错了事，但我不太了解如何在对象上调用我的函数。

您可以使用变量名称SavingsAccount，后跟“。”和您要调用的方法来调用方法。

所以，而不是

//Check balance
 System.out.println(test); // Will give a memory address

您可以这样做，例如：

  public static void main(String[] args){
    //Setting values, balance, deposit, withdraw.
    SavingsAccount savings = new SavingsAccount(2000, 100, 2000);
    SavingsAccount test = new SavingsAccount(5000, 200, 100);

    test.checkBalance();
  }

或

public static void main(String[] args){
    //Setting values, balance, deposit, withdraw.
    SavingsAccount savings = new SavingsAccount(2000, 100, 2000);
    SavingsAccount test = new SavingsAccount(5000, 200, 100);

    test.deposit(50);
    test.checkBalance();
}

考虑到这一点，也许在构造SavingsAccount时仅指定起始余额更为有意义。希望这会有所帮助！

Answer 2

您好，您可以实现toString来打印对象，如下所示：

package com.stuart.livealert;

public class SavingsAccount {
    // Class
    int balance;
    int amountToDeposit;
    int amountToWithdraw;

    //Constructor
    public SavingsAccount(int initialBalance, int deposit, int withdraw){
        balance = initialBalance;
        amountToDeposit = deposit;
        amountToWithdraw = withdraw;
    }

    //Functions thats I wanna call

    // Setting balance
    public void checkBalance() {
        System.out.println("Hello!");
        System.out.println("Your balance is " + balance);
    }

    // Depositing amounts
    public void deposit(int amountToDeposit) {
        balance = balance + amountToDeposit;
        System.out.println("You just deposited" + amountToDeposit);
    }
    // Withdrawing amounts
    public int withdraw(int amountToWithdraw) {
        balance = balance - amountToWithdraw;
        System.out.println("You just withdrew" + amountToWithdraw);

        return amountToWithdraw;
    }

    @Override
    public String toString() {
        return "{balance : " + balance + " deposit : " + amountToDeposit + " withdraw : " + amountToWithdraw + " }";
    }

    // Main
    public static void main(String[] args){
        //Setting values, balance, deposit, withdraw.
        SavingsAccount savings = new SavingsAccount(2000, 100, 2000);
        SavingsAccount test = new SavingsAccount(5000, 200, 100);


        //Check balance
        System.out.println(test); // Will give {balance : 5000 deposit : 200 withdraw : 100 }

    }
}

Answer 3

您可以在构造函数中调用函数：

public SavingsAccount(int initialBalance, int deposit, int withdraw){
    balance = initialBalance;
    deposit(deposit);
    withdraw(withdraw);
    checkBalance();
}

然后，您将看到所有System.out消息，而无需更改主要方法。

在我的SavingsAccount对象上调用函数并打印结果

3 个答案: