Question

我有一个实现NamedAccount.java的BankAccount.java，它是一个抽象接口，但它一直给我一个错误，因为BankAccount.java不是抽象的，它不能覆盖它。我该如何解决这个问题？我尝试在两种情况下添加@Override但它不起作用！

BankAccount.java：

public class BankAccount implements NamedAccount {

   private String myCustomer;
   private double myBalance;
   private double myInterest;
   protected int myMonthlyWithdrawCount;
   protected double myMonthlyServiceCharges;

   public BankAccount(final String theNameOfOwner, 
                      final double theInterestRate) {
      myCustomer = theNameOfOwner;
      myInterest = theInterestRate;
      myBalance = 0.0;
      myMonthlyWithdrawCount = 0;
      myMonthlyServiceCharges = 0;
   }

   public double getBalance() {
      return myBalance;   
   }

   public boolean processDeposit(final double theAmount) {
      boolean trueDeposit = false;
      if (theAmount > 0) {
         myBalance += theAmount;
         trueDeposit = true;
      }
      return trueDeposit;       
   }

   public boolean processWithdrawal(final double theAmount) {
      boolean trueWithdrawal = false;
      if (theAmount > 0 && theAmount > myBalance) {
         myBalance -= theAmount;
         trueWithdrawal = true;
      }
      return trueWithdrawal; 
   }

   public double calculateInterest() {
      return myBalance * (myInterest / 12.0);
   }

   public void performMonthlyProcess() {
      myBalance -= myMonthlyServiceCharges;
      myBalance += calculateInterest();
      myMonthlyWithdrawCount = 0;
      myMonthlyServiceCharges = 0.0;
      if (myBalance < 0.0) {
         myBalance = 0.0;
      }
   }
}

NamedAccount.java：

 public interface NamedAccount {
   String getAccountHolderName();
   void setAccountHolderName(final String theNewName);
 }

要让它运行，你需要这个SafeDepositBoxAccount.java：

 public class SafeDepositBoxAccount implements NamedAccount {


       private String mySafeName;

       public SafeDepositBoxAccount(final String theNameOfHolder) {
          mySafeName = theNameOfHolder;   
       }

       public String getAccountHolderName() {
          return mySafeName;
       }

       public void setAccountHolderName(final String theNewName) {
          mySafeName = theNewName;
       }
     }

Answer 1

错误告诉您必须覆盖这些方法（来自您的界面），因为该类不是abstract。如果你使类抽象，那么你就不需要覆盖这些方法。像，

private String accountHolderName;
@Override
public String getAccountHolderName() {
    return accountHolderName;
}
@Override
public void setAccountHolderName(final String theNewName) {
    this.accountHolderName = theNewName;
}

Answer 2

由于您的班级BankAccount表示它实施NamedAccount，您需要实施合同中定义的menthod here，即setAccountHolderName和getAccountHolderName在您的BankAccount类中，或者作为编译器，您需要将您的类定义为抽象类，因此其他类可以扩展您的抽象类并定义这两个方法以形成具体的类。

如果您想摆脱编译错误，那么您需要覆盖这两个方法，就像您在SafeDepositBoxAccount类中定义的那样：

public class BankAccount implements NamedAccount {
    .....
    private String accountHolderName;
    @Override
    public String getAccountHolderName() {
         return accountHolderName;
    }
    @Override
    public void setAccountHolderName(final String theNewName) {
         this.accountHolderName = theNewName;
    }
 }

Answer 3

在你的代码中，NamedAccount是一个接口，任何实现接口的类（在这种情况下为 BankAccount 和 SafeDepositBoxAccount ）必须实现所有接口的方法，除非class被声明为 abstract 。

对于 BankAccount 类，既没有提供getAccountHolderName和setAccountHolderName的实现，也没有将NamedAccount类标记为 abstract 。因此发生了此错误。

有两种解决方案：

将BankAccount类声明为abstract，
或者为getAccountHolderName和。编写实现 setAccountHolderName方法。

注意：当方法声明旨在覆盖超类中的方法声明时，使用@Override。 BankAccount中的任何方法在超类中都没有相应的方法，所以你不能@Override。

Answer 4

public abstract class BankAccount implements NamedAccount {

    abstract String getAccountHolderName();

    abstract void setAccountHolderName(final String theNewName);

}

Java覆盖抽象接口方法

4 个答案: