Java导入给定错误

再一次，我是一个JavaN00B，我试图从头开始学习，遇到了一些令人尴尬的问题

我得到了一个Account类，如下所示：Account.java

 public class Account 
 {
    protected double balance;

    // Constructor to initialize balance
    public Account( double amount )
{
    balance = amount;
}

    // Overloaded constructor for empty balance
    public Account()
{
    balance = 0.0;
}

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

    public double withdraw( double amount )
{
            // See if amount can be withdrawn
    if (balance >= amount)
    {
        balance -= amount;
                    return amount;
    }
    else
            // Withdrawal not allowed
                    return 0.0;
}

    public double getbalance()
{
            return balance;
}
  } 

 import Account;

 class InterestBearingAccount extends Account
  {
    // Default interest rate of 7.95 percent (const)
    private static double default_interest = 7.95;

    // Current interest rate
    private double interest_rate;

    // Overloaded constructor accepting balance and an interest rate
    public InterestBearingAccount( double amount, double interest)
{
    balance = amount;
    interest_rate = interest;
}

    // Overloaded constructor accepting balance with a default interest rate
    public InterestBearingAccount( double amount )
{
    balance = amount;
    interest_rate = default_interest;
}

    // Overloaded constructor with empty balance and a default interest rate
    public InterestBearingAccount()
{
    balance = 0.0;
    interest_rate = default_interest;
}

    public void add_monthly_interest()
{
            // Add interest to our account
    balance = balance +
                    (balance * interest_rate / 100) / 12;
}

 }

我试图使用extends来继承这个类中的方法和变量。所以，我使用了InterestBearingAccount.java

 public class Account 
 {
    protected double balance;

    // Constructor to initialize balance
    public Account( double amount )
{
    balance = amount;
}

    // Overloaded constructor for empty balance
    public Account()
{
    balance = 0.0;
}

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

    public double withdraw( double amount )
{
            // See if amount can be withdrawn
    if (balance >= amount)
    {
        balance -= amount;
                    return amount;
    }
    else
            // Withdrawal not allowed
                    return 0.0;
}

    public double getbalance()
{
            return balance;
}
  } 

 import Account;

 class InterestBearingAccount extends Account
  {
    // Default interest rate of 7.95 percent (const)
    private static double default_interest = 7.95;

    // Current interest rate
    private double interest_rate;

    // Overloaded constructor accepting balance and an interest rate
    public InterestBearingAccount( double amount, double interest)
{
    balance = amount;
    interest_rate = interest;
}

    // Overloaded constructor accepting balance with a default interest rate
    public InterestBearingAccount( double amount )
{
    balance = amount;
    interest_rate = default_interest;
}

    // Overloaded constructor with empty balance and a default interest rate
    public InterestBearingAccount()
{
    balance = 0.0;
    interest_rate = default_interest;
}

    public void add_monthly_interest()
{
            // Add interest to our account
    balance = balance +
                    (balance * interest_rate / 100) / 12;
}

 }

我在尝试编译时收到一个错误，提示导入错误“.”。所有文件都在同一个文件夹中

---

我做了javac-cp。Interest BearingAccount

如果所有文件都在同一文件夹/包中，则无需进行导入。

如果您的类在同一个包中，则无需导入。否则，您应该导入包+类名。

将InterestBearingAccount类公开，如

public class InterestBearingAccount {}

---

定义类时，可以选择在文件顶部包含

包

语句。这就要求类所属的包与其在文件系统中的位置相关联。例如，包

com.foo

中的公共类

Account

应在以下文件层次结构中定义：

com
 |
 |--foo
     |
     |--Account.java

---

由于您省略了

package

语句，所以您的两个类都属于匿名包。对于属于同一包的类，无需导入类来引用它们；这只是不同包中的类的一个要求。

如果它们在同一个包中，则不需要导入。那么，包到底是什么？它是一个包含所有必需类的文件夹吗？你知道如何在互联网上搜索，对吗？package是文件夹的名称？文件夹的层次结构表示包名称。在上面的示例中，包是com.foo，因此您将在Account.java中添加“package com.foo'”作为第一行。