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class hello
{
	public static void main ( String[] args )
    {
      System.out.println("Hello World!");
    }
}
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Output: 
Hello World!
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/* Comments, Haiku Poetry
Write out three lines of a poem.
The poem describes a single moment in time,
using 17 syllables.
*/

// Write three lines of a poem to the computer monitor
class Haiku
{
	public static void main ( String[] args )
	{
        System.out.println("On a withered branch");
        System.out.println("A crow has just alighted:");
        System.out.println("Nightfall in autumn.");
	}
}
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Output: 
On a withered branch
A crow has just alighted:
Nightfall in autumn.
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class HelloPlanets
{
	public static void main ( String[] args )
	{
         String[] planets = {"Mercury", "Venus", "Earth", 
                             "Mars", "Jupiter",  "Saturn",  
                             "Uranus", "Neptune", "Pluto"};
         for ( int j=0; j< planets.length; j++ )
         {
           system.out.println("Hello " + planets[j] +"!" );
         }
	}
}
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output: 
hello mercury!
hello venus!
hello earth!
hello mars!
hello jupiter!
hello saturn!
hello uranus!
hello neptune!
hello pluto!
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class idexamples
{
	public static void main ( string[] args )
	{
        long   hoursworked = 40;    
        double payrate     = 10.0, taxrate = 0.10;
		    
        system.out.println("Hours Worked: " + hoursworked);
        system.out.println("Pay/hour   $: " + payrate); 
        system.out.println("pay Amount $: " + (hoursworked * payrate) );
        system.out.println("tax Rate    : " + taxrate);
        system.out.println("tax Amount $: " + (hoursworked * payrate * taxrate) );
    	system.out.println("Take home  $: " + ((hoursworked * payrate) - 
                                               (hoursworked * payrate * taxrate)) );
	}
}
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output: 
hours worked: 40
pay/hour   $: 10.0
pay amount $: 400.0
tax rate    : 0.1
tax amount $: 40.0
take home  $: 360.0
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import java.io.*;
class echo
{
	public static void main (string[] args) throws ioexception
			/* throws IOException - is necessary for programs that do input...
			It informs the compiler that main() does an input operation that might fail. 
			When the program is running and an input operation fails, the computer system 
			will be informed of the failure and the program will be gracefully halted. 
			When an input or an output operation fails, an exception is generated.
			An exception is an object (a chunk of main memory) that contains information about what went wrong. 
			The section of code where the problem occurred can deal with the problem itself, or pass the exception on. 
			Passing the exception on is called throwing an exception. */ 
	{
            InputStreamReader inStream = new InputStreamReader(System.in);
            BufferedReader stdin = new BufferedReader( inStream );
 
            String inData;

            System.out.println("Enter the data:");
            inData = stdin.readLine();

            System.out.println("You entered: " + inData );
	}
}
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1st Output: 
Enter the data:

(Enter a response:)
(enter something...)

2nd Output/Response:
You entered: enter something...
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import java.io.*;
class EchoSquare
{
	public static void main (String[] args) throws IOException
	{ 
           BufferedReader stdin = 
               new BufferedReader ( new InputStreamReader(System.in));
	   //works the same as :
	   //InputStreamReader inStream = new InputStreamReader(System.in);
	   //BufferedReader stdin = new BufferedReader( inStream );
      
           String inData;
           int    num, square;                  // declaration of two int variables

           System.out.println("Enter an integer:");
           inData = stdin.readLine();
          
           num    = Integer.parseInt( inData ); // convert inData to int
           square = num * num ;                 // compute the square

           System.out.println("The square of " + inData + 
							" is: " + square );
	}
}
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1st Output: 
Enter an integer:

(Enter a response:)
(4)

2nd Output/Response:
The square of (4) is: 16

An error exception might look like this:
Enter an integer:
14.92
java.lang.NumberFormatException: 14.92 
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import java.io.*;
class RestaurantTip
{
	public static void main (String[] args) throws IOException
	{
	   String charData, tipData;
	   double basicCost, tipRate;
	   BufferedReader stdin = 
		   new BufferedReader ( new InputStreamReader(System.in));

	   System.out.println("Enter Meal cost:");
	   charData   = stdin.readLine();
	   basicCost  = ( Double.valueOf( charData  ) ).doubleValue();

	   System.out.println("Enter tip rate:") ;
	   tipData = stdin.readLine();
	   tipRate = Double.parseDouble( tipData )  ;

	   System.out.println("Meal $ " + basicCost + ", tax $ " + (basicCost*0.06) +
			      ", tip $ " + (basicCost*tipRate) + " = Total $ " + 
			      (basicCost + basicCost*0.06 + basicCost*tipRate));
	}
}
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1st Output: 
Enter Meal cost:
(Enter a response:)
(39.45)

2nd Output:
Enter tip rate:
(Enter a response:)
(0.075)

Final Output/Response:
Meal $ 39.45, tax $ 2.367, tip $ 2.95875 = Total $ 44.77575
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