Using GET and POST methods in J2ME

Most of the mobile applications are not alone. They frequently communicate with web services or web applications to accomplish their tasks. Lets see how to make GET and POST requests to a server.
We can use HttpConnection class to make requests.
Lets see what are the basic steps.

Python Note 8 (Python Utilities)

Summary
filenames = os.listdir(dir) -- list of filenames in that directory path (not including . and ..). The filenames are just the names in the directory, not their absolute paths.

import os

dir="c:/"
files=os.listdir(dir)
for path in files:
    print(path)
                 

Output :
addins
AppCompat
AppPatch
assembly
avastSS.scr
bfsvc.exe

Python Note 7 (the pickle module)

In python we can use serialization functionality using pickle module. it can save live instances of objects to files and retrieve object instances from pickled files.
Code:

import pickle

class Transaction : 
 def __init__(self,userName,trnsID,payment):
  self.userName=userName
  self.trnsID=trnsID
  self.payment=payment
 
 def __del__(self):
  print("Destructed!")
 
 def getPaymentValue(self):
  return self.payment
 
 def getUserName(self) :
  return self.userName
#end of the class

Python Summary

[Read All]

Python Note 6(Classes and Objects)

Sample Code  : General class

#define a class
class User :
 def __init__(self,name,user_id,acc_balance):
  self.Name=name
  self.User_id=user_id
  self.Acc_Balance=acc_balance
  
 def recharge(self,amount):
  self.Acc_Balance+=amount
 
 def withdraw(self,amount):
  if amount <= self.Acc_Balance :
   self.Acc_Balance-=amount
  else :
   pass #do nothing
 
 def getBalance(self): #parameter less method
  return self.Acc_Balance
  
 def __del__(self) :
  print("Destructor started!")
#end of the class
 
usr=User("Kanishka",1133,27000.00)
print("User {0} , Balance {1:5.2f}".format(usr.Name,usr.getBalance()))
usr.withdraw(2000.50) #withdrwaw money
print("User {0} , Balance {1:5.2f}".format(usr.Name,usr.getBalance()))

Python Note 5 (File Handling)

File handling is very easy in python, Lets see an example

datafile=open("myfile.dat","w") #open a file for writing
datafile.write("Sri Lanka,India,Pakistan,Bhutan,Australlia,Canada") #write data
datafile.write("\n")
datafile.write("Apple,Orange,Mango")
datafile.close() #release the file

#reading from the file
datafile=open("myfile.dat","r") #open file for reading
record=datafile.readline()#reding a line (here it is the first line)
mylist=record.strip("\n").split(",") #remove newline character and split the string by comma
print(mylist)
print(len(mylist))

Python Note 4( String Formatting)

Code

import math 

for x in range(1,20) :
 print ("{0:2d} {1:3d} {2:5d}".format(x,x*2,x*3))
 
tmplate="My {} is {}"
print(tmplate.format("country","Sri Lanka"))
print(tmplate.format("name","Kanishka"))

tmplate="Hello {name} , your role is {role}"
print(tmplate.format(name="Kanishka",role="Admin"))
print(tmplate.format(name="Sampath",role="User"))

print("The value of 'PI' is approximately {0:0.3f}".format(math.pi))
print("The value of 'e' is approximately {0:0.5f}".format(math.e))

#old formatting
print('The value of PI is approximately %5.3f' % math.pi)

Result

Python Note 3 (Functions)

We can define number of functions in same python script.
Code

#function1
def cube(x) :
 return x**3

#function2
def maxVal(x,y) :
 if x > y :
  return x
 else :
  return y

print (cube(3))
print (maxVal(12,22))

Python Note 2 (String manipulations)

Code

mystr="Sri Lanka"
print( len(mystr) )
print( mystr.upper() )
print( mystr.lower() )
print( mystr[1])
print( mystr[-1])

Python Note 1

Python is an interpreted language. Nesting is done using indentation. I have used Python 3.2.2 in this note.

Sample python program demonstrating Python operators.

J2ME with LWUIT (UI Toolkit Widgets) part 3

In this note, I would like to note down how to create a Ticker, Calendar
Any label can be configured as a Ticker.

• Ticker

            Image ico = Image.createImage("/img/arrow.png");
            Label lblTicker = new Label("Hello! This is a Ticker!");
            lblTicker.setIcon(ico);

            Form frm=new Form();
            frm.addComponent(lblTicker);
            frm.show();
                    
            //finally
            lblTicker.startTicker(100, true);

J2ME with LWUIT (UI Toolkit Widgets) part 2

Lets see how to use Tabbed pane, ComboBox TextArea, TextField

• TabbedPane

I am going to use Containers with TabbedPanes because it provides an easy way to organize widgets

J2ME with LWUIT (UI Toolkit Widgets) part 1

There are very important UI widgets available in LWUIT lets demonstrate them.

J2ME with LWUIT (Commands)

Definitely we may need to use commands because users must have a simple way to command our app. Though we can use buttons to get user commands, it may not be the best options. By using commands we can easily place the frequently used commands in our app.

J2ME with LWUIT (Initializing)

LWUIT is a SWING like lightweight widget library for J2ME. It is very useful for software development with J2ME. I could find a very useful guide for LWUIT. It is available here.

LWUIT class hierarchy is useful when we use LWUIT wifgets.

Queries in HIBERNATE

Querying is one of most important part in Hibernate. For this purpose we have to use HQL (Hibernate Query Language). HQL is simpler than SQL and bit differ from SQL. Here in HQL we consider on Classes instead of Tables and we consider on Attributes instead of Columns.
Lets see how to querying from Hibernate.
For this example I have used a College , Student relation which is a one to many association.

Many to Many Mapping

One To Many Mapping

One to One Bi Directional mapping

One To One Mapping

Inheritance Mapping

Basically there are 3 types of inheritance mapping. We may use those methods suitably.

• SINGLE_TABLE (default)
• JOINED
• TABLE_PER_CLASS

Model

Compound Primary Keys in HIBERNATE

Most of the time we need only 1 primary key. But there are some situations we may need compound primary keys.
Here in hibernate it is simple. We can use 2 classes into 1 table strategy.

Account.java

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Account {

 private AccountCompoundKey compoundKey;
 private int accBalance;
 
 @Id
 public AccountCompoundKey getCompoundKey() {
  return compoundKey;
 }
 public void setCompoundKey(AccountCompoundKey compoundKey) {
  this.compoundKey = compoundKey;
 }
 public int getAccBalance() {
  return accBalance;
 }
 public void setAccBalance(int accBalance) {
  this.accBalance = accBalance;
 } 
}