1 /*
2 * File: ShowFile.java
3 *
4 *
5 * This Java applet divides the applet area into two parts: an area
6 * with controls such as buttons and choices, called controlPanelNorth,
7 * and an area called dataPanel which has a TextArea to display
8 * data from a file. The dataPanel is a separate class.
9 *
10 * The data points are read from a file which has the following format:
11 * an integer which is the number of items in the file
12 * items: each item has an integer id no., a name, and a floating
13 * point price
14 *
15 * The data is read once from the file into a set of arrays. Then the
16 * data can be displayed in different ways depending on the controls.
17 *
18 */
19
20 import java.awt.*;
21 import java.awt.event.*;
22 import java.io.*;
23 import java.net.*;
24
25 public class ShowFile extends java.applet.Applet
26 implements ItemListener, ActionListener
27 {
28 Font f = new Font("TimesRoman", Font.ITALIC, 18);
29
30 DisplayPanel dataPanel; // the display panel, from the class below
31 String inname; // name of the data file
32
33 Choice dataChoice; // control for type of data
34 Button showfile; // display the data under current controls
35 Label title; // label of the display
36
37 public void init()
38 { InputStream instream = null;
39 Panel controlPanelNorth = new Panel();
40
41 setLayout(new BorderLayout());
42
43 // initialize the input stream and data panel
44 try
45 { inname = getParameter("inputfile");
46 instream = new URL(getDocumentBase(), inname).openStream();
47 dataPanel = new DisplayPanel(instream);
48 }
49 catch (IOException e)
50 { System.err.println
51 ("I/O Exception: probably bad filename or bad connection."
52 + e.getMessage());
53 }
54
55 // make the control panel
56 controlPanelNorth.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5));
57
58 title = new Label("Grocery Items");
59 title.setFont(f);
60
61 dataChoice = new Choice();
62 dataChoice.setFont(f);
63 dataChoice.addItem("Fruits");
64 dataChoice.addItem("Veggies");
65 dataChoice.addItemListener(this);
66
67 showfile = new Button("Show Items");
68 showfile.setFont(f);
69 showfile.addActionListener(this);
70
71 controlPanelNorth.add(title);
72 controlPanelNorth.add(dataChoice);
73 controlPanelNorth.add(showfile);
74
75
76 // add the two components to the applet area
77 add(controlPanelNorth, BorderLayout.NORTH);
78 add(dataPanel, BorderLayout.CENTER);
79 }
80
81 public void itemStateChanged(ItemEvent e)
82 {
83 if (e.getSource() == dataChoice)
84 {
85 dataPanel.settype (dataChoice.getSelectedItem());
86 }
87 }
88
89 public void actionPerformed(ActionEvent e)
90 {
91 if (e.getSource() == showfile)
92 {
93 dataPanel.displayfile();
94 }
95 }
96 }
97
98 class DisplayPanel extends Panel
99 {
100 String datatype = "Fruits"; // either "Fruits" or "Veggies"
101 StringBuffer buff;
102 Font f = new Font("Monospaced", Font.ITALIC, 18);
103 TextArea ta;
104
105 // variables to hold the data from the file
106 int numdata;
107 int itemnumbers[];
108 String itemnames[];
109 double itemprices[];
110 int maxlength;
111
112 InputStreamReader isr;
113
114 public DisplayPanel(InputStream instream)
115 {
116 setLayout(new BorderLayout());
117 ta = new TextArea("Grocery Item Display Area . . .", 20, 30);
118 add( ta, BorderLayout.CENTER );
119
120 try
121 {
122 isr = new InputStreamReader(instream);
123 StreamTokenizer intokens = new StreamTokenizer(isr);
124 intokens.parseNumbers(); intokens.slashSlashComments(true);
125
126 /* read the number of data points and allocate data arrays */
127 int tok = intokens.nextToken();
128 numdata = (int) intokens.nval;
129
130 itemnumbers = new int[numdata];
131 itemnames = new String[numdata];
132 itemprices = new double[numdata];
133
134 // read data items
135 maxlength = 0;
136 for (int i=0; i<numdata; i++)
137 { tok = intokens.nextToken(); itemnumbers[i] = (int)intokens.nval;
138 tok = intokens.nextToken(); itemnames[i] = intokens.sval;
139 tok = intokens.nextToken(); itemprices[i] = intokens.nval;
140 maxlength = Math.max(maxlength, itemnames[i].length());
141 }
142
143 /* for debugging
144 for (int i=0; i<numdata; i++)
145 { System.out.println(itemnumbers[i]);
146 System.out.println(itemnames[i]);
147 System.out.println(itemprices[i]);
148 }
149 */
150 }
151 catch (IOException e)
152 { System.err.println
153 ("I/O Exception: Reading data from file"
154 + e.getMessage());
155 }
156 }
157
158 public void settype (String s)
159 { datatype = s;
160 }
161
162 public void displayfile()
163 {
164 buff = new StringBuffer();
165 ta.setFont (f);
166 Color fruitcolor = new Color(127, 0, 0);
167 Color vegcolor = new Color(0, 127, 127);
168
169 for (int i=0; i<numdata; i++)
170 { if (datatype.equals("Fruits") && itemnumbers[i]<=1000)
171 appendtext(fruitcolor, itemnumbers[i], itemnames[i], itemprices[i]);
172 if (datatype.equals("Veggies") && itemnumbers[i]>1000)
173 appendtext(vegcolor, itemnumbers[i], itemnames[i], itemprices[i]);
174 }
175 ta.setText(buff.toString());
176 }
177
178 public void appendtext (Color c, int n, String s, double d)
179 {
180 ta.setForeground (c);
181 int diff = maxlength - s.length();
182
183 buff.append( n + " " + s);
184 for (int i=0; i<diff; i++) buff.append(" ");
185 buff.append( " $" + d + "\n");
186 }
187 }