Question

在refreshFields方法下，我试图在AccountApplet类中显示帐户ID和余额，getId（）和getBalance（）都在Account类中，我该怎么做？

这是帐户类

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.border.*;

public class Account extends Exception
{
  int id         = 1234;
  double balance = 1000.00;

  Account (int id, double balace)
  {
  }

  public int getId()
  {

    return id; // placeholder
  }

  public double getBalace()
  {
    return balance;  //  placeholder
  }

  public void setBalance(double balance) throws NegativeAmountException
  {

  }

  public void deposit(double amount) throws NegativeAmountException
  {

  }

  public void withdraw(double amount) throws NegativeAmountException,
                                             InsufficientFundsException
  {

  }

}

这是accountApplet类

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.border.*;

public class AccountApplet extends JApplet implements ActionListener
{    
  //  For West
  public JLabel  ai       = new JLabel("Account ID ");
  public JTextField  aitf = new JTextField();
  public JLabel  ab       = new JLabel("Account Balance ");
  public JTextField  abtf = new JTextField();

  //  For East
  public JButton     dp   = new JButton ("Deposit");
  public JTextField  dptf = new JTextField();
  public JButton       wt = new JButton ("Withdraw");
  public JTextField  wttf = new JTextField();

  // For South
  public JLabel  status   = new JLabel("placeholder");  


  public void init()
  {
    this.setSize(400, 90);

    //----------------------
    //  Set up the Structure
    //----------------------

    Container      c = getContentPane();
    JPanel         b = new JPanel(new BorderLayout());
    JPanel      west = new JPanel(new GridLayout(2,2));
    JPanel      east = new JPanel(new BorderLayout());
    JPanel depo_with = new JPanel(new GridLayout(2,2));



    // Add BorderLayout to the container
    c.add(b);

    // Add everything to West
    b.add(west, BorderLayout.WEST);


    west.setBorder(new TitledBorder("Display Account Information"));
    west.add(ai);
    west.add(aitf);
    aitf.setEditable(false);
    west.add(ab);
    west.add(abtf);
    abtf.setEditable(false);

    // Add everything to EAST
    b.add(east, BorderLayout.EAST);

    east.setBorder(new TitledBorder("Deposit or Withdrawl Funds"));

    east.add(depo_with, BorderLayout.EAST);

    depo_with.add(dptf);
    depo_with.add(dp);
    depo_with.add(wttf);
    depo_with.add(wt);

    dp.addActionListener(this);
    wt.addActionListener(this);

    // Add everything to EAST
    b.add(status, BorderLayout.SOUTH);






  }  // End intit

  public void actionPerformed(ActionEvent e)
  {
    if (e.getSource() == dp)  //  Executes if deposit was clicked
    {
    }    

    if (e.getSource() == wt)  //  Executes if withdraw was clicked
    {
    }
  }  // End actionPerformed

  public void refreshFields()
  {
    getId();
    // diplays accound id and balance in left text fields
    //should be called when the applet is first displayed and after each valid transaction
  }

  public double getAmount(JTextField tf) throws EmptyFieldException,
                                                NumberFormatException,
                                                NegativeAmountException
  {
    return 5.0;
  }  //  End getAmount


} // End Class

Answer 1

您需要Account对象的实例来访问它的字段。

您可以使用JTextField方法更新setText(String text)个对象的值。

  public void refreshFields()
  { 
    Account theAccount = new Account();
    aitf.setText(theAccount.getId());
    abtf.setText(theAccount.getBalace());
    // diplays accound id and balance in left text fields
    //should be called when the applet is first displayed and after each valid transaction
  }

您可能希望将getBalace()方法更改为getBalance()。

另外，为Account对象添加新的构造函数：

  Account ()
  {
  }

显示其他类的信息

1 个答案: