Quotes MIDlet
/*
Learning Wireless Java
Help for New J2ME Developers
By Qusay Mahmoud
ISBN: 0-596-00243-2
*/
import java.util.Enumeration;
import javax.microedition.rms.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.io.*;
import java.io.*;
public class QuotesMIDlet extends MIDlet implements CommandListener {
Display display = null;
List menu = null; // main menu
List choose = null;
TextBox input = null;
Ticker ticker = new Ticker("Database Application");
String quoteServer =
"http://quote.yahoo.com/d/quotes.csv?s=";
String quoteFormat = "&f=slc1wop"; // The only quote format supported
static final Command backCommand = new Command("Back", Command.BACK, 0);
static final Command mainMenuCommand = new Command("Main", Command.SCREEN, 1);
static final Command saveCommand = new Command("Save", Command.OK, 2);
static final Command exitCommand = new Command("Exit", Command.STOP, 3);
String currentMenu = null;
// Stock data
String name, date, price;
// record store
StockDB db = null;
public QuotesMIDlet() { // constructor
}
// start the MIDlet
public void startApp() throws MIDletStateChangeException {
display = Display.getDisplay(this);
// open a db stock file
try {
db = new StockDB("mystocks");
} catch(Exception e) {}
menu = new List("Stocks Database", Choice.IMPLICIT);
menu.append("List Stocks", null);
menu.append("Add A New Stock", null);
menu.addCommand(exitCommand);
menu.setCommandListener(this);
menu.setTicker(ticker);
mainMenu();
}
public void pauseApp() {
display = null;
choose = null;
menu = null;
ticker = null;
try {
db.close();
db = null;
} catch(Exception e) {}
}
public void destroyApp(boolean unconditional) {
try {
db.close();
} catch(Exception e) {}
notifyDestroyed();
}
void mainMenu() {
display.setCurrent(menu);
currentMenu = "Main";
}
// Construct a running ticker
// with stock names and prices
public String tickerString() {
StringBuffer ticks = null;
try {
RecordEnumeration e = db.enumerate();
ticks = new StringBuffer();
while(e.hasNextElement()) {
String stock1 = new String(e.nextRecord());
ticks.append(Stock.getName(stock1));
ticks.append(" @ ");
ticks.append(Stock.getPrice(stock1));
ticks.append(" ");
}
} catch(Exception ex) {}
return (ticks.toString());
}
// Add a new stock to the record store
// by calling StockDB.addNewStock()
public void addStock() {
input = new TextBox("Enter a Stock Name:", "", 5, TextField.ANY);
input.setTicker(ticker);
input.addCommand(saveCommand);
input.addCommand(backCommand);
input.setCommandListener(this);
input.setString("");
display.setCurrent(input);
currentMenu = "Add";
}
// Connect to quote.yahoo.com and
// retrieve the data for a given
// stock symbol.
public String getQuote(String input) throws IOException, NumberFormatException {
String url = quoteServer + input + quoteFormat;
StreamConnection c = (StreamConnection)Connector.open(
url, Connector.READ_WRITE);
InputStream is = c.openInputStream();
StringBuffer sb = new StringBuffer();
int ch;
while((ch = is.read()) != -1) {
sb.append((char)ch);
}
return(sb.toString());
}
// List the stocks in the record store
public void listStocks() {
choose = new List("Choose Stocks", Choice.MULTIPLE);
choose.setTicker(new Ticker(tickerString()));
choose.addCommand(backCommand);
choose.setCommandListener(this);
try {
RecordEnumeration re = db.enumerate();
while(re.hasNextElement()) {
String theStock = new String(re.nextRecord());
choose.append(Stock.getName(theStock)+" @ " +
Stock.getPrice(theStock),null);
}
} catch(Exception ex) {}
display.setCurrent(choose);
currentMenu = "List";
}
// Handle command events
public void commandAction(Command c, Displayable d) {
String label = c.getLabel();
if (label.equals("Exit")) {
destroyApp(true);
} else if (label.equals("Save")) {
if(currentMenu.equals("Add")) {
// add it to database
try {
String userInput = input.getString();
String pr = getQuote(userInput);
db.addNewStock(pr);
ticker.setString(tickerString());
} catch(IOException e) {
} catch(NumberFormatException se) {
}
mainMenu();
}
} else if (label.equals("Back")) {
if(currentMenu.equals("List")) {
// go back to menu
mainMenu();
} else if(currentMenu.equals("Add")) {
// go back to menu
mainMenu();
}
} else {
List down = (List)display.getCurrent();
switch(down.getSelectedIndex()) {
case 0: listStocks();break;
case 1: addStock();break;
}
}
}
}
class StockDB {
RecordStore recordStore = null;
public StockDB() {}
// Open a record store with the given name
public StockDB(String fileName) {
try {
recordStore = RecordStore.openRecordStore(fileName, true);
} catch(RecordStoreException rse) {
rse.printStackTrace();
}
}
// Close the record store
public void close() throws RecordStoreNotOpenException,RecordStoreException {
if (recordStore.getNumRecords() == 0) {
String fileName = recordStore.getName();
recordStore.closeRecordStore();
recordStore.deleteRecordStore(fileName);
} else {
recordStore.closeRecordStore();
}
}
// Add a new record (stock)
// to the record store
public synchronized void addNewStock(String record) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream outputStream = new DataOutputStream(baos);
try {
outputStream.writeUTF(record);
} catch (IOException ioe) {
System.out.println(ioe);
ioe.printStackTrace();
}
byte[] b = baos.toByteArray();
try {
recordStore.addRecord(b, 0, b.length);
} catch (RecordStoreException rse) {
System.out.println(rse);
rse.printStackTrace();
}
}
// Enumerate through the records.
public synchronized RecordEnumeration enumerate() throws
RecordStoreNotOpenException {
return recordStore.enumerateRecords(null, null, false);
}
}
class Stock {
private static String name, time, price;
// Given a quote from the server,
// retrieve the name,
//price, and date of the stock
public static void parse(String data) {
int index = data.indexOf('"');
name = data.substring(++index,(index = data.indexOf('"', index)));
index +=3;
time = data.substring(index, (index = data.indexOf('-', index))-1);
index +=5;
price = data.substring(index, (index = data.indexOf('<', index)));
}
// Get the name of the stock from
// the record store
public static String getName(String record) {
parse(record);
return(name);
}
// Get the price of the stock from
// the record store
public static String getPrice(String record) {
parse(record);
return(price);
}
}
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