返回变量java时遇到问题

每次运行它时，我都不会得到任何返回变量。我所看到的只是过程完成的文本。正在寻求帮助

您没有输出任何内容。使用

System.out.println

输出账户余额，例如

public class Account
{
static int accountNum;
static int nextAccountNum = 112200;
static double balance;


    public static void main(String args[])
    {
        Account checkingAccount = new Account(1500.00);
        Account savingAccount = new Account(1000.00);
        Account moneyMarketAccount = new Account(500.00);

        checkingAccount.getAccountNumber();
        savingAccount.getAccountNumber();
        moneyMarketAccount.getAccountNumber();

    }

    public Account(double bal)
    {
        balance = bal;
        accountNum = nextAccountNum;
        nextAccountNum++;
    }

}

---

另外，将

accountNum

和

balance

变量设置为非

static

，否则余额和帐号将被每个新实例覆盖。

一个问题是

accountNum

和

balance

被声明为

static

。您需要将它们作为实例字段，以便

Account

的每个实例都有自己的值

没有得到输出的原因是

main（）

方法创建了几个

Account

对象，但不处理它们

System.out.println(checkingAccount.getAccountNumber());

---

将主函数与具有多个实例的类分离通常是一种很好的做法。getter和setter方法用于正确封装类变量，这可能是帐户应该具备的。下面是一个例子

Main.java

public class Account
{
    static int nextAccountNum = 112200;
    int accountNum;
    double balance;

    public static void main(String args[])
    {
        Account checkingAccount = new Account(1500.00);
        Account savingAccount = new Account(1000.00);
        Account moneyMarketAccount = new Account(500.00);

        checkingAccount.getAccountNumber();
        savingAccount.getAccountNumber();
        moneyMarketAccount.getAccountNumber();

        System.out.println("Checking: " + checkingAccount.toString());    
        System.out.println("Savings: " + savingAccount.toString());    
        System.out.println("Money market: " + moneyMarketAccount.toString());    
    }

    public Account(double bal)
    {
        balance = bal;
        accountNum = nextAccountNum;
        nextAccountNum++;
    }

    @Override
    public String toString() {
        return "Account " + accountNum + ": balance=" + balance;
    }    
}

public class Main {
    public static void main(String args[])
    {
        Account checkingAccount = new Account(1,1500.00);
        Account savingAccount = new Account(2,1000.00);
        Account moneyMarketAccount = new Account(3,500.00);

        System.out.println("Account " + checkingAccount.getAccountNumber() 
                + " has balance of: " + checkingAccount.getBalance());
        System.out.println("Account " + savingAccount.getAccountNumber() 
                + " has balance of: " + savingAccount.getBalance());
        System.out.println("Account " + moneyMarketAccount.getAccountNumber() 
                + " has balance of: " + moneyMarketAccount.getBalance());
    }
}

Account.java

public class Account
{
    static int nextAccountNum = 112200;
    int accountNum;
    double balance;

    public static void main(String args[])
    {
        Account checkingAccount = new Account(1500.00);
        Account savingAccount = new Account(1000.00);
        Account moneyMarketAccount = new Account(500.00);

        checkingAccount.getAccountNumber();
        savingAccount.getAccountNumber();
        moneyMarketAccount.getAccountNumber();

        System.out.println("Checking: " + checkingAccount.toString());    
        System.out.println("Savings: " + savingAccount.toString());    
        System.out.println("Money market: " + moneyMarketAccount.toString());    
    }

    public Account(double bal)
    {
        balance = bal;
        accountNum = nextAccountNum;
        nextAccountNum++;
    }

    @Override
    public String toString() {
        return "Account " + accountNum + ": balance=" + balance;
    }    
}

public class Main {
    public static void main(String args[])
    {
        Account checkingAccount = new Account(1,1500.00);
        Account savingAccount = new Account(2,1000.00);
        Account moneyMarketAccount = new Account(3,500.00);

        System.out.println("Account " + checkingAccount.getAccountNumber() 
                + " has balance of: " + checkingAccount.getBalance());
        System.out.println("Account " + savingAccount.getAccountNumber() 
                + " has balance of: " + savingAccount.getBalance());
        System.out.println("Account " + moneyMarketAccount.getAccountNumber() 
                + " has balance of: " + moneyMarketAccount.getBalance());
    }
}

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你希望得到什么？打印输出？