问如何实现个人号码校验6位数的Luhn算法？

EN

public class Bank {    
private String bank_name;   // Name of the Bank.
private Scanner input;      // private scanner to retrieve
                            // user input
// Some Booleans to control program flow
private boolean bContinue = true;
private boolean bAcc = true; 
// constructors
Bank()  {}
Bank(String b_name)
{
    // Name of Bank is set in constructor
    bank_name = b_name;    }
int processClients()
{
    System.out.println("\t" + bank_name.toUpperCase());
    System.out.println("==========================================");        
    // System has a possible 32 accounts to be used 
    Account[] pAccounts = new Account[32];        
    // In the following loop we initialise the accounts all to null 
    // which makes it easier to find a terminating account when     
    // looping later on in the code - as we can check if an account 
    // is null and subsequently know that no accounts in the array  
    // after such point have been initialised.                    
    int counter = 0;
    while( counter < 32)
    {
        pAccounts[counter] = null;
        counter++;
    }
    // Some variables for temporarily storing       
    // account credentials in before setting up account 
    String tmp_name_f, tmp_name_l;
    double tmp_bal;
    long tmp_num;        
    // initalise scanner here to begin gathering user input 
    input = new Scanner(System.in);        
     // Below we will being adding accounts to the database / array 
    // this loop continues till a terminating condition is met.    
    System.out.println("Begin Adding 
Accounts\n==========================================");
    for( int i = 0; i < pAccounts.length; i++)
    {
        System.out.println("Account Holders First Name :: ");
        tmp_name_f = input.next();
        System.out.println("Account Holders Last Name :: ");
        tmp_name_l = input.next();
        System.out.println("BSB - AccountNumber :: ");
        tmp_num = input.nextLong();
        System.out.println("Opening Balance :: ");
        tmp_bal = input.nextDouble(); 
        // Store Information in Account Object Array by
        // initialising accounts as we precede          
        pAccounts[i] = new Account(new Client( tmp_name_f, tmp_name_l  ), 
tmp_bal, tmp_num); 
        // Check if user wishes to add another account, if "N" 
        // is entered, we break out of account creation loop   
        System.out.println("Add Another Account ? (Y / N) :: ");
        if(input.next().equals("N"))
            break;
    }        
//The boolean here, indicates user wishes to continue utilising the 
Banking System 
    while (bContinue)
    {
        int acc;    // account index to access.
        System.out.println("\nSelect Account - 
Index\n==========================================");
        for ( int k = 0; k < pAccounts.length; k++)
        {
            // earlier we initialised accounts to null                                     
            // this check is just to ensure the account is valid and has 
been instantiated 
            if(pAccounts[k] != null)
            System.out.println(k + " ) " + pAccounts[k].get_name() + 
            "\nAccount Number : " + pAccounts[k].get_account_number() );
        }
        acc = input.nextInt(); 
        // This Boolean indicates the user wishes to continue on with the 
same account 
        while (bAcc)
        {
            // This could be done in a switch statement, however i prefer 
if's.
            // basically, we select which member function of Account to call  
            // for the account designated in the code above, each selection  
            // either fetches or changes values of a specific account 
denoted 
            // by index.                                                     
            System.out.println("\nChoose Function\n1 ) Deposit\n2 ) 
Withdraw\n3 ) Balance Enquiry\n4 ) Change Contact Details");
            int sel = input.nextInt();
            if ( sel == 1)
            {
                System.out.println("Enter Amount to Deposit = $ ");                
                pAccounts[acc].deposit_funds(input.nextDouble() );
            }
            else if ( sel == 2)
            {
                System.out.println("Enter Amount To Withdraw = $ ");
                if( pAccounts[acc].withdraw_funds(input.nextDouble() ) == 
-1)
                {
                    System.out.println("Insufficient Funds");
                }
                else
                    System.out.println("Take your Funds");
            }
            else if ( sel == 3)
            {
                System.out.println("Balance = $ " + String.format("%.2f", 
pAccounts[acc].get_balance()) );
            }
            else if (sel == 4)
            {
                System.out.println("Current Contact Number : " + 
pAccounts[acc].getClient().getPhoneNumber() );
                /*
                 * You could in here also have an option to change contact 
details
                 * a call such as
                 * pAccounts[acc].getClient().set_or_change_phoneContact( 
55202020 )
                 * would do this
                 */                }
            else
                System.out.println("Invalid Selection"); 

            // Check if user would like to change accounts or continue with 
current account
            System.out.println("Continue With This Account\n1 ) Yes\n2 ) 
No");
            if( input.nextInt() == 1)
                    bAcc = true;
            else bAcc = false;
        }
        bAcc = true;            
        // Check if to continue on with banking system.
        System.out.println("Would You Like To Continue\n1 ) Yes\n2 ) No");
        if (input.nextInt() == 1) bContinue = true;
        else
            return 0;   // we return early and essentially exit program        
    }
    return 0;
}    
public static void main(String[] args)
{
   Bank myBank = new Bank("National Australia Bank");
   System.exit( myBank.processClients() );
}
}

public class Client { 
private String name_first, name_last;
private long phone_contact;

// default constructor
Client()    {}

// Overload Constructor    
Client(String name_f, String name_lst)
{
    name_first = name_f;
    name_last = name_lst;

    // this is here for example only        
    // it is up to you to implement functions        
    // to set / change this value through banking
    // program. A basic function is included below

    phone_contact = 999999;
} 

// method to return full name
String getName()
{
    return (name_first + " " + name_last);
      }
void changeFirstName(String n_new)
{
    name_first = n_new;
}
void changeLastName(String n_new)
{
    name_last = n_new;
}
void change_phone_number(long p_number)
{

    phone_contact = p_number;
}
long getPhoneNumber()
{
    return phone_contact;
}   
}

public class Account {    
// variables contained within class account 

// accessible only via methods/functions as 

// they are private and subsequently can    

// only be changed via member functions.    

private Client person;            // account holders client

private double balance;           // current account balance

private long account_number;      // account number

// Constuctor for Objects of type account //

Account( Client c_client, double c_balance, long c_num)
{
    person = c_client;
    balance = c_balance;
    account_number = c_num;
}
// Function to deposit funds into an account //

public void deposit_funds( double p_amount)
{
    balance += p_amount;
}
// function to withdraw funds from an account //
    // checks to see whether funds are available. //

public int withdraw_funds( double p_amount)
{
    // check if enough funds
    if ( p_amount > balance )
        return -1;
    else
        balance -= p_amount;
    return 0;
} 

// returns account balance 
public double get_balance()
{
    return balance;
}

// returns account holders name
public String get_name()
{

    // Access our client object (person)
    // then access getName() function
    // of Client class
    return person.getName();
}
// returns account number //
public long get_account_number()
{
    return account_number;
}
public Client getClient()
{
    return person;
}
}