关于包的问题

Question

看你定义类的时候,采用什么关键字了

Answer 1

下面是全部代码//A reusable GUI for the examples in this chapter
package com.deitel.jhtp3.ch17;
import java.awt.*;
import javax.swing.*;public class BankUI extends JPanel{
protected final static String names[]={"Account number","First name","Last name","Balance","Transaction Amount"
};
protected JLabel labels[];
protected JTextField fields[];
protected JButton doTask,doTask2;
protected JPanel innerPanelCenter,innerPanelSouth;
protected int size=4;
public static final int ACCOUNT=0,FIRST=1,LAST=2,BALANCE=3,TRANSACTION=4;

public BankUI(){
this(4);
}

public BankUI(int mySize){
size=mySize;
labels=new JLabel[size];
fields=new JTextField[size];

for(int i=0;i<labels.length;i++)
labels[i]=new JLabel(names[i]);

for(int i=0;i<fields.length;i++)
fields[i]=new JTextField();

innerPanelCenter=new JPanel();
innerPanelCenter.setLayout(new GridLayout(size,2));

for(int i=0;i<size;i++){
innerPanelCenter.add(labels[i]);
innerPanelCenter.add(fields[i]);
}

doTask=new JButton();
doTask2=new JButton();
innerPanelSouth=new JPanel();
innerPanelSouth.add(doTask);
innerPanelSouth.add(doTask2);

setLayout(new BorderLayout());
add(innerPanelCenter,BorderLayout.CENTER);
add(innerPanelSouth,BorderLayout.SOUTH);
validate();

}


public JButton getDoTask(){ return doTask;}
public JButton getDoTask2(){return doTask2;}
public JTextField[] getFields(){return fields;}

public void clearFields(){
for(int i=0;i<size;i++)
fields[i].setText("");
}

public void setFieldValues(String s[]) throws IllegalArgumentException{
if(s.length!=size) throw new IllegalArgumentException(
"There must be"+size+"strings in the array");

for(int i=0;i<size;i++)
 fields[i].setText(s[i]);

}

public String[] getFileValues(){
String values[]=new String[size];
for(int i=0;i<size;i++)
values[i]=fields[i].getText();
return values;
}
}
package com.deitel.jhtp3.ch17;
import java.io.Serializable;public class BankAccountRecord implements Serializable{
private int account;
private String firstName;
private String lastName;
private double balance;

public BankAccountRecord(){
this(0,"","",0.0);
}

public BankAccountRecord(int acct,String first,String last,double bal){
setAccount(acct);
setFirstName(first);
setLastName(last);
setBalance(bal);
}

public void setAccount(int acct){
account=acct;
}

public int getAccount(){return account; }

public void setFirstName(String first){
firstName=first;
}

public String getFirstName(){ return firstName; }

public void setLastName(String last){
lastName=last;
}

public String getLastName(){ return lastName;}

public void setBalance(double bal){
balance=bal;
}

public double getBalance(){return balance; }
}import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import com.deitel.jhtp3.ch17.BankUI;
import com.deitel.jhtp3.ch17.BankAccountRecord;public class CreateSequentialFile extends JFrame{
private ObjectOutputStream output;
private BankUI userInterface;
private JButton enter,open;

public CreateSequentialFile(){
super("Creating a Sequential File of objects");
getContentPane().setLayout(new BorderLayout());
userInterface=new BankUI();

enter=userInterface.getDoTask();
enter.setText("Enter");
enter.setEnabled(false);
enter.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e)
{
addReccord();
}
}
       );
       
    addWindowListener(
     new WindowAdapter(){
     public void windowClosing(WindowEvent e)
     {
     if(output!=null){
     addRecord();
     closeFile();
     }
     else
        System.exit(0);
        }
     }
        );
        
     open=userInterface.getDoTask2();
     open.setText("Save as");
     open.addActionListener(
      new ActionListener(){
                 public void actionPerformed(ActionEvent e)
                  {
                   openFile();
                  }   
                 } 
                );
                
          getContentPane().add(userInterface,BorderLayout.CENTER);
          setSize(300,300);
          show();
}    private void openFile()
    {
     JFileChooser fileChooser=new JFileChooser();
     fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
    
     int result=fileChooser.showSaveDialog(this);
    
     if(result==JFileChooser.CANCEL_OPTION)
       return;
       
       File fileName=fileChooser.getSelectedFile();
       
     if(fileName==null||fileName.getName().equals(""))
       JOptionPane.showMessageDialog(this,"Invalid File Name",
                                           "Invalid File Name",
                                            JOptionPane.ERROR_MESSAGE);
        else
         try{
          output=new ObjectOutputStream(
          new FileOutputStream(fileName) );
          open.setEnabled(false);
          enter.setEnabled(true);
         }catch(IOException e){
          JOptionPane.showMessageDialog(this,"Error Opening File",
                                              "Error",JOptionPane.ERROR_MESSAGE);
          System.exit(1);
         
         }
         }
         
         
    private void closeFile(){
     try{
     output.close();
     System.exit(0);
     }catch(IOException ex){
     JOptionPane.showMessageDialog(this,"Error closing file",
                                        "Error",JOptionPane.ERROR_MESSAGE);
     System.exit(1);
     }
    }
    
    public void addRecord(){
     int accountNumber=0;
     BankAccountRecord record;
     String fieldValues[]=userInerface.getFieldValues();
    
     if(!fieldValues[0].equals("")){
     try{
     accountNumber=Integer.parseInt(fieldValues[0]);
    
     if(accountNumber>0){
         record=new BankAccountRecord(accountNumber,fieldValues[1],
                                      fieldValues[2],
                                      Double.parseDouble(fieldValues[3]));
         output.writeObject(record);
         output.flush();
     }
    
     userInterface.clearFields();
     }catch(NumberFormatException nfe){
     JOptionPane.showMessageDialog(this,"Bad Account number or balance",
                                         "Invalid Number Format",
                                         JOptionPane.ERROR_MESSAGE);
     }
     catch(IOException io){
     closeFile();
     }
     }
    }
    
        public static void main(String args[]){
         new CreateSequentialFile();
        }}