abstractaccountview.java

java 编程源代码

// AbstractAccountView.java
// AbstractAccountView is an abstract class that represents
// a view of an Account.
package com.deitel.advjhtp1.mvc.account;

// Java core packages
import java.util.*;
import java.awt.*;

// Java extension packages
import javax.swing.JPanel;
import javax.swing.border.*;

public abstract class AbstractAccountView extends JPanel 
   implements Observer {
   
   // Account to observe
   private Account account;
   
   // AbstractAccountView constructor
   public AbstractAccountView( Account observableAccount )
      throws NullPointerException
   {
      // do not allow null Accounts
      if ( observableAccount == null )
         throw new NullPointerException();
      
      // update account data member to new Account
      account = observableAccount;
      
      // register as an Observer to receive account updates
      account.addObserver( this );      
      
      // set display properties
      setBackground( Color.white );
      setBorder( new MatteBorder( 1, 1, 1, 1, Color.black ) );
   }
   
   // get Account for which this view is an Observer
   public Account getAccount()
   {
      return account;
   }
   
   // update display with Account balance
   protected abstract void updateDisplay();
   
   // receive updates from Observable Account
   public void update( Observable observable, Object object )
   {
      updateDisplay();
   }
}

/***************************************************************
 * (C) Copyright 2002 by Deitel & Associates, Inc. and         *
 * Prentice Hall. All Rights Reserved.                         *
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 * DISCLAIMER: The authors and publisher of this book have     *
 * used their best efforts in preparing the book. These        *
 * efforts include the development, research, and testing of   *
 * the theories and programs to determine their effectiveness. *
 * The authors and publisher make no warranty of any kind,     *
 * expressed or implied, with regard to these programs or to   *
 * the documentation contained in these books. The authors     *
 * and publisher shall not be liable in any event for          *
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 * arising out of, the furnishing, performance, or use of      *
 * these programs.                                             *
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