Understanding Abstract Classes and Interfaces - Java Programming: Comprehensive Concepts and Techniques - page 648

Using a Callback Mechanism in a Class

Because the StockFrame object is created by the LogonFrame, the
StockFrame must be coded first. Figure 10-41 displays the code for the
StockFrame class. Lines 9 through 14 import packages used by the class,
including those used to create the user interface.

1 /*
2

Chapter 10: The StockFrame Class

3 Programmer: Michael Mick

4 Date: December 5, 2007

5 Filename: StockFrame.java

6 Purpose: Provides a user interface for a stock list to test the Password class

7 */
8
9 import javax.swing.*;
10 import java.awt.*;
11 import java.awt.event.*;
12 import java.util.*;
13 import java.io.*;
14 import javax.swing.border.TitledBorder;
15
16 class StockFrame extends JFrame implements ActionListener , WindowListener
17 {
18
19 //define instance variables

20 String stockSymbol;

21
22 JTextField jtfStockSymbol;

23 JButton jbtAddStock, jbtLogout;

24 JComboBox jcbStockList;

25 Activator caller;

26
27 public StockFrame ( User user, Activator callerObj )

28 {

29 super ( "Add Stock Symbols" ) ; // call super (JFrame) constructor

30
31

int width = 330;

32 int height = 170;

33 caller = callerObj; // save reference to caller object

34
35 // Define components for panel 1

36 JLabel label1 = new JLabel ( "Symbol:" ) ;

37 jtfStockSymbol = new JTextField ( 4 ) ;

38 jbtAddStock = new JButton ( "Add Symbol" ) ;

39
40 JPanel p1= new JPanel () ;

41 p1.setLayout ( new GridLayout ( 1,3 )) ;

42 p1.add ( label1 ) ;

43 p1.add ( jtfStockSymbol ) ;

44 p1.add ( jbtAddStock ) ;

45 p1.setBorder ( new TitledBorder ( "Add stock symbol" )) ;

46
47 // Define components for panel 2

48 JLabel label2 = new JLabel ( "Click arrow to view list" ) ;

49 jcbStockList = new JComboBox () ;

50
51 JPanel p2= new JPanel () ;

52 p2.setLayout ( new GridLayout ( 1,2 )) ;

53 p2.add ( label2 ) ;

54 p2.add ( jcbStockList ) ;

55 p2.setBorder ( new TitledBorder ( "View stock symbols" )) ;

56
57 // D fi t f l 3

FIGURE 10-41