Beginners

Difference??

System.out.print("Hello world");

System.out.println("Hello world");

//"println" makes a new line.

'\n' will also work for making new lines

so it will look like..
System.out.print("Hello world \n");

Tired of typing :-“System.out.println()”


“out” in “System.out” is a static PrintStream object, you can do this easily by creating a PrintStream variable, assign “System.out” to it, and reference that object from the new variable.

example:-

import java.io.*;

class Helloworld
{
private static PrintStream out = System.out;

public static void main(String args[])
{
out.println("Hello world");

}
}

So now you may also be eager to know what public static void main(String[] args) is for...?


public
The keyword public indicates that the method can be called by any object

static
The keyword static indicates that the method is a class method, which can be called without the requirement to instantiate an object of the class

void
The keyword void indicates that the method doesn't return any value.

args
The formal parameter args is an array of type String, which contains arguments entered at the command line.

Remember that the args parameter is mandetory.

The length Property
In Java, args is a true array object. Array objects have a property named length.

The runtime system monitors for the entry of command-line arguments by the user and constructs the String array containing those arguments.

Processing Command-Line Arguments
The args.length property can be used by the code in the program to determine the number of arguments actually entered by the user.

If the array of strings contains data, the first string in the array corresponds to the first argument

Can i get help for java packages. If there is any website please send reply soon.
i got some websites, but its not giving me the basics.

you can use this link to kno the basics:-

http://java.sun.com/docs/books/tutorial/java/package/index.html

Refer...JAVA.. Complete Reference Book

please help me

public void createConnection(){
try {
initCtx = new InitialContext();
envCtx = (Context)initCtx.lookup("java:comp/env");
}catch (Exception e) {
e.printStackTrace();
System.out.println("Context not established");
}

//Look up the data source
try{
ds = (DataSource)envCtx.lookup("jdbc/mydatabase");
conn = ds.getConnection();
} catch(Exception e){
e.printStackTrace();
System.out.println("DataSource not allocated");
}

after querying the database I close the connection using conn.close()

Any help regarding this will be very useful.

I want to know how to close the database while using try catch. I close the database connection using conn.close(). but its giving some fatal error. And if i didnt close the database connection its asking for it.

please see to this.

put your catch exception after closing your connection.