你如何添加接受交易，並將其添加到交易的列表是調整一個帳戶

Question

這裏的平衡陣列的代碼，我至今對Account類

public class Account { 
    Transcation transcation[]; 
    private int account; 



public Account(){ 
    transcation = new Transcation[5]; 


} 
private void setAccount(int account){ 
    this.account = account; 

} 
public int getAccount(){ 
    return account; 
} 

public performTranscation(){ 
    return transcation; 
} 

的方法

}

Answer 1

public class Account { 
    private Transaction[] transactions = new Transaction[0]; 
    private BigDecimal balance = BigDecimal.ZERO; 

    public performTransaction(Transaction transaction) { 
     transactions = transactions.copyOf(transactions, transactions.length + 1; 
     transactions[transactions.length - 1] = transaction; 
     balance = balance.plus(transaction.getDelta()); 
    } 
} 

public class Transaction { 
    private final BigDecimal delta; 

    public Transaction(BigDecimal delta) { 
     this.delta = delta; 
    } 

    public BigDecimal getDelta() { 
     return delta; 
    } 
} 

但是你應該使用ArrayList不是一個數組;它會更有效率，因爲您不需要每次都複製數組。

public class Account { 
    private final List<Transaction> transactions = new ArrayList<Transaction>(); 
    private BigDecimal balance = BigDecimal.ZERO; 

    public performTransaction(Transaction transaction) { 
     transactions.add(transaction); 
     balance = balance.plus(transaction.getDelta()); 
    } 
} 

Answer 2

定義爲交易EnumSet：

EnumSet<Transcation> transactions;