1. Java- I/O, SMS etc
N Amanquah

2. File I/O
RecordStore
SMS
Assorted

3. FileI/O- output –chap 15
FileConnection API of the GCF provides the streams for I/O
String url=“file:///root1/photos/myfile”
FileConnection fc = (FileConnection)Connector.open(url);
try {
if (!fc.exists())
fc.create();
OutputStream rawOut = fc.openOutputStream();
PrintStream out = new PrintStream(rawOut);
try { out.println(“Hello into a file"); }
finally { out.close(); } }
finally { fc.close(); }

4. FileI/O-input String url=“file:///root1/photos/myfile”
FileConnection fc = (FileConnection)Connector.open(url);
try {
Inputstream in =fc.openInputStream();
//in.read() //read from file }
finally { in.close(); }
finally { fc.close(); }

5. File I/O See API for other interesting functions
Install app by OTA to have private directory for midlet created by emulator.
Access to system folders:
String system.getProperty(“fileconn.dir.photos”)
If returns a directory URL or NULL
fileconn.dir.videos
fileconn.dir.graphics
fileconn.dir.tones
fileconn.dir.music
fileconn.dir.recordings

6. File I/O
Example –kb 15 illustrates creating a directory, file, write & read, remove file & dir.
Application must be signed to suppress all the notifications
Fileconnection is cleaner, consistent on most devices
Can access images, sounds, other files
App must be signed.(permissions)

7. RecordStore –chap 14
Recordstore data is for midlet suite. (by default)
RecordStore rs=RecordStore.openRecordStore(“name”, true)
//true= create if one does not exist
Write:
Byte[] data…
Int id=rs.addRecord(data, 0,data.length)
Read:
Byte[] rec=rs.getRecord(id) //read a particular record

8. RecordStore while (re.hasNextElement()) {
To obtain id to use:
RecordEnumeration re=rs.enumerateRecords(null,null,false)
3 Params: recordFilter, recordComparator, keepCurrentIfChanged?
To fetch all records, use:
while (re.hasNextElement()) {
byte[] record = re.nextRecord();
….//process the records
See kb 14: in following code, store and read back key-value pairs

9. RecordStore-write
RecordStore rs = RecordStore.openRecordStore(mName, true);
try {
Enumeration keys = mMap.keys();
while (keys.hasMoreElements()) {
String key = (String)keys.nextElement();
String value = (String)mMap.get(key);
byte[] record = packRecord(key, value);
rs.addRecord(record, 0, record.length); }
catch (IOException ioe) {
System.out.println("Error packing in " + mName + " : " +
key + " -> " + value);
finally { rs.closeRecordStore(); }
private byte[] packRecord(String key, String value)
throws IOException {
ByteArrayOutputStream raw = new ByteArrayOutputStream();
DataOutputStream out = new DataOutputStream(raw);
out.writeUTF(key);
out.writeUTF(value);
return raw.toByteArray();

10. RecordStore-read private void read() throws RecordStoreException {
RecordStore rs = RecordStore.openRecordStore(mName, true);
mMap = new Hashtable();
try {
RecordEnumeration re =
rs.enumerateRecords(null, null, false);
while (re.hasNextElement()) {
byte[] record = re.nextRecord();
parseRecord(record); }
finally { rs.closeRecordStore(); }
private void parseRecord(byte[] record) {
ByteArrayInputStream raw = new ByteArrayInputStream(record);
DataInputStream in = new DataInputStream(raw);
String key = in.readUTF();
String value = in.readUTF();
mMap.put(key, value);
catch (IOException ioe) {
System.out.println("Bad record in " + mName + ".");

11. Messaging –chap 19 WMA =wireless messaging API, both sms & mms
Based on the GCF, use the Connetor to get MessageConnection
Import javax.wireless.messaging
4 lines of code to send sms
obtain a connector
Get a message with newMessage()
Fill the message ie setPayLoad()
Send()

12. Sending SMS import javax.wireless.messaging
Public void sendText(String addr, String text) throws IOException, InterruptedException{
String cs=“sms://”+addr + port;
MessageConnection mc=(MessageConnection)Connector.open(cs);
TextMessage tm=(TextMessage)mc.newMessage(MessageConnection. TEXT_MESSSAGE);
tm.setPayloadText(text);
mc.send(tm) }
//NB: port number is optional, if omitted= normal text msg

13. Receiving SMS Create a MessageConnection without a destination string
Put application in push registry, (with a static registration)
Two options:
Loop on MessageConnection ‘s receive() method (thread)
(it blocks)
Use a thread to listen for incoming messages. Register a listener.
Its notifyIncomingMessage() will be called
See kb-19

14. Push registry
Allows incoming network connection to launch up application
To register, provide
Connection string eg sms://:50000
A class name that describes the midlet to be launched.
String representing allowed senders (use * for all connections)
Dynamic registration – see chapter 6
To register: Make the ff calls from within a thread:
PushRegistry.registerConnection(connStr, midletName, “*”)
To unregister:
PushRegistry.unregisterConnection(connStr)
//only one param

15. Push registry- static registration
Go to project properties Application Descriptor push registry add.
To find incomming connections, call PushRegistry’s listConnections(), pass false to get every input
Returns array of connections.
Run kb-06 OTA whether static or dyanamic registration is used.
Use the WMA utility console to send sms to the emulator

16. Push registry- timed execution
Dynamic !
Call PushRegistry.registerAlarm(“midletname”, long_time)
Do this in a thread, ie the registration.
Run kb-06 OTA

17. Other topics Cool methods:
boolean Display. flashBacklight(int duration)
boolean Display. vibrate(int duration)
(both return false if feature is not supported, duration in ms)
Contacts & Calendar: chapter 16 of kickbutt book
Parsing XML: chapter 21
Parsing RSS: chapter 21

18. Use of Netbeans
Drag and Drop approach to app development

19. Lab work
Build an application that does the following: Make use of netbeans:
Fetch data from the user (the user’s preferences)
Send it by sms to another number.
Store the data you have collected in a record store so that it can be retrieved the next time the user runs the program.
One menu item should allow the user to enter the values afresh, or to fetch the saved values.