Free Online Java Tutorials and Examples

Palindrome Number Example

2010-06-21T17:51:00.000-07:00

This blog post explains you what is palindrome number and a java example to calculate palindrome number.

Palindrome Number
Palindrome Number is the same number after reversing the actual number.

For Example : 545 (After reversing, the output is same)

The example of palindrom number below :

import java.io.*;

public class Palindrome {
public static void main(String [] args){
try{
BufferedReader object = new BufferedReader(
new InputStreamReader(System.in));
System.out.println("Enter a number");
int num= Integer.parseInt(object.readLine());
int n = numb;
int rev=0;
System.out.println("The Number is : ");
System.out.println(" "+ numb);
for (int i=0; i<=num; i++){
int r=numb%10;
numb=numb/10;
rev=rev*10+r;
i=0;
}
System.out.println("Output after reversing: "+ " ");
System.out.println(" "+ rev);
if(n == rev){
System.out.print("This Number is Palindrome!");
}
else{
System.out.println("This Number is not palindrome!");
}
}
catch(Exception e){
System.out.println("Unknown Number!");
}
}
}

Write To File Example

2010-06-12T20:18:00.001-07:00

This post will expain you the two classes - FileWriter and BufferedWriter and how to write java program to write to a file.

Class FileWriter - The FileWriter is a class used for writing character files.

Class BufferedWriter - The BufferWriter class is used to write text to a character-output stream, buffering characters. It will help us to provide for the efficient writing of single characters, arrays, and strings.

Find the code below of java program to write text to a file:

import java.io.*;
class FileWrite
{
public static void main(String args[])
{
try{
// Create file
FileWriter fstream = new FileWriter("out.txt");
BufferedWriter out = new BufferedWriter(fstream);
out.write("Hello Java");
//Close the output stream
out.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}

Example to Determine if a File or Directory Exists

2009-11-26T07:17:00.000-08:00

This program checks whether the file or directory exist in your computer or not. This can be possible using exists() method and in the example we are using if condition to check whether the given file or directory exists or not. The example is given below :

import java.io.*;
public class filedirexists{
public static void main(String args[])
{
File filedir=new File("File or Directory exists or not!!")
boolean exists = filedir.exists()
if (!exists)
{
System.out.println("The File/Directory you are looking for is not found")
}
else
{
System.out.println("The File/Directory you are looking for available")

Comparing Two Dates

2009-11-15T07:10:00.000-08:00

Here your will find the example to compare two dates in java. We use java.util.Date class and compareTo() method for comparison. The compareTo() method returns integer value when we comparing two dates.

The compareTo() method returns the following integer value if comparing two dates :

The integer value '0' returns if both dates are equal.
The integer value '1' returns when first date is greater than second date.
The integer value '-1' returns when first date is less than second date.

Here is the example of comparing 2 dates and display the final result :

import java.util.Date;
public class Comparedates{

public static void main(String[] args) {
Date Date1 = new Date();
try{
Thread.sleep(1000);
}catch(Exception e){
}
Date Date2 = new Date();
System.out.println("First Date:="+Date1);
System.out.println("Second Date:="+Date2);
if(Date1.compareTo(Date2) > 0)
System.out.println("Date1 is Greater than Date2");
else if(Date1.compareTo(Date2) < 0)
System.out.println("Date1 is less than Date2");
else
System.out.println("Date1 and Date2 are equal!!!");
}
}

JDBC and JDBC Driver Connectivity

2009-03-25T04:08:00.000-07:00

The JDBC or Java database connectivity is a unique technology that empowers applications to be written once but run anywhere. JDBC enabled devise driver could access corporate data even if the environment is not homogeneous. This unique feature is very much Java specific for Java itself is platform independent and Java API which is actually a short term of JDBC enables the easy execution of SQL statements.

JDBC is an application program to the core used to access database in tubular format encrypted by Java and driven by standard interfaces. RDBMS like SQL and Oracle are quarried and updated by JDBC with its niche in using and allowing heterogeneous implementation with the same application.

Since SQL is supported by all Relational Database Management System any corporate database could be accessed, quarried or updated via this single Java written JDBC program. In order to interact with database Java interface is used by programmers but it is the job of a JDBC driver to implement the interface according to the data base management system. Though Java Database Connectivity Driver categorically implements connection some are better suited for specific applications over the other types.

Four types of JDBC driver connectivity are common with Type 1 driver heading the list. It’s a popular, platform independent driver that uses ODBC to connect to database. Type 2 Native API driver is not coded by Java in its entirety making it more versatile in interpreting client libraries of database into recognizable native calls.

Application server, namely middle tier technology is used by Type 3 drivers and therefore client software is not required and database access could be gained through internet.

A type 4 driver also known as Native Protocol Driver and is a complete Java written program, which displays superior performance over the other two types and is completely platform independent. Communication with client application is speedy and easy as direct conversion of JDBC into vendor database protocol is enabled excluding middleware function; however a separate client side driver is required for a different database which poses the only challenge at times.

Changing Mouse Icon Example

2009-03-17T06:31:00.000-07:00

In this example, you will learn how to change the cursor icon. In this program, the cursor will change when user moov the mouse to "Yes" button and then "No" button. The source code is available below :

import java.awt.*;
import java.awt.event.*;

public class ChangeCursor{
public static void main(String[] args) {
Frame m = new Frame("Change cursor");
Panel panel = new Panel();
Button b1 = new Button("Yes");
Button b2 = new Button("No");
panel.add(b1);
panel.add(b2);
m.add(panel,BorderLayout.CENTER);
m.setSize(300,300);
m.setVisible(true);
Cursor c1 = b1.getCursor();
Cursor c2 = b2.getCursor();
b1.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
b2.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
m.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent we){
System.exit(0);
}
});

}
}

Disable Keyboard Editing in JSpinner

2008-12-31T04:52:00.000-08:00

A simple example on JSpinner. In the example, the editing mode is disabled using setEditable() method. So it will not be possible to insert numbers with the help of keyboard :

import javax.swing.*;
import java.awt.*;

public class Disablekeyboard{
public static void main(String[] args){
JFrame frm = new JFrame("Disable Keyboard Editing Example");
JSpinner spinner = new JSpinner();
JFormattedTextField tf = ((JSpinner.DefaultEditor)spinner.getEditor())
.getTextField();
tf.setEditable(false);
spinner.setValue(new Integer(100));
JPanel panel = new JPanel();
panel.add(spinner);
frm.add(panel, BorderLayout.NORTH);
frm.setSize(350, 350);
frm.setVisible(true);
frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Java sort() Method Example

2008-10-16T04:00:00.000-07:00

If you want to sort string characters then this example is the best for you. The sort() method sort words in ascending order. Look a simple example of sort() method given below :

import java.util.*;
import java.io.*;
import java.lang.String;

public class sortstr{
public static void main(String args[]){
String str = "Java String Example";
char[] content = str.toCharArray();
java.util.Arrays.sort(content);
String sorted = new String(content);
System.out.println(content);
}
}

Result : EJSaaegilmnprtvx

Show Icon on The Button

2008-09-26T02:59:00.000-07:00

With the help of java swing, you can add images, icons in the application to make your GUI application interface more attractive. With the help of this example, you can learn how to add image on the button or other control. This example expain you add image file. The code is given below :

import javax.swing.*;
import java.awt.*;

public class IconButton{
public static void main(String[] args){
JFrame frame = new JFrame("Swing Icon Example");
JButton button = new JButton("My Button");
Icon imgicon = new ImageIcon("smiley_icon.gif");
JPanel panel = new JPanel();
button.setIcon(imgicon);
panel.add(button);
frame.add(panel, BorderLayout.NORTH);
frame.setSize(380, 380);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Swing Input Dialog Box

2008-09-13T03:54:00.000-07:00

Input dialog box in java is the good example of user input example in GUI environment. A user can input value at run time in small window. The input box also contains "OK" and "Cancel" button. The code below is the example to create an input box where user enter either text or numeric value at run time :

import javax.swing.*;
import java.awt.event.*;

public class ShowInputDialog{
public static void main(String[] args){
JFrame frame = new JFrame("Input Dialog Box Example");
JButton button = new JButton("Click for Input Dialog Box");
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae){
String txt = JOptionPane.showInputDialog(null, "Enter Your Text : ",
"Input Box", 1);
if(txt != null)
JOptionPane.showMessageDialog(null, "The text you have entered : " + txt,
"Input Box", 1);
else
JOptionPane.showMessageDialog(null, "You clicked on cancel button.",
"Input Box", 1);
}
});
JPanel panel = new JPanel();
panel.add(button);
frame.add(panel);
frame.setSize(350, 350);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

Comparing Two Strings Using equals()

2008-09-02T21:24:00.000-07:00

The given example show you how to compare two strings with the help of equals() method in java. The equals() method is used to compare the contents of objects. The method returns value in either "true" or "false". The code give below compare two strings whether both are equal or not. If both are same then it returns true else not :

import java.lang.*;
import java.io.*;

public class equalstrings{
public static void main(String[] args) throws IOException{
System.out.println("String Compares Example Using Equals() Method");
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter First String:");
String str1 = bf.readLine();
System.out.println("Enter Second String to Compare :");
String str2 = bf.readLine();
if (str1.equals(str2)){
System.out.println("Both the Strings are Equal!");
}
else{
System.out.println("Both the Strings are not Equal!");
}
}
}

Java String Length Example

2008-08-23T09:09:00.000-07:00

If you want to count the lenght of the string in java then use lenght() method that returns integer value of a string entered by the user. Below is the example that calculate the length of the string :

import java.lang.*;
import java.io.*;

public class Strlen{
public static void main(String[] args) throws IOException{
System.out.println("Count the Lenght of String");
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter String:");
String str = bf.readLine();
int len = str.length();
System.out.println("Length of Text : " + len);
}
}

Java Prime Number Example

2008-07-01T20:49:00.000-07:00

What is Prime Number?

Definition : A prime number is a natural number that has only two divisor. Either it is divisible by 1 or itself and it is greater than 1. So we can say it has only one divisor means it can only divided by itself.

Here is the example of prime number in Java. It display all the prime numbers between 1 and the limit entered by user. Get the source code of prime number example here :

import java.io.*;
class Primenumberexample {
public static void main(String[] args) throws Exception{
BufferedReader bf = new BufferedReader(
new InputStreamReader(System.in));
System.out.println("Enter Limit to Print Prime Number :");
int k = Integer.parseInt(bf.readLine());
System.out.println("Prime Numbers Are : ");
for (int i=1; i < k; i++ ){
for (int j=2; j < i; j++){
int a = i%j;
if (a==0){
break;
}
}
if(i == j){
System.out.print(" "+i);
}
}
}
}

How to Calculate Area of Rectangle?

2008-06-30T21:28:00.000-07:00

This example explain you how to calculate area of a rectangle using java code. For calculating area of rectangle, we need three variables. One for length, one for breadth and one variable calculate the area of rectangle. We have already read and know how to calculate area of rectangle using formula a=lXb. Here is the source code to find the area of rectangle :

class Rectangleexample
{
public static void main(String[] args)
{
int len=5, breadth=7, area=1;
area = len*breadth;
System.out.println("Area if Rectangle :" + area);
}
}

Count Vowels Example in Java

2008-06-21T08:57:00.000-07:00

This example show you how to check and calculate how many vowel are in the string entered by user. With the help of for loop, we calculate how many vowels a user entered in the string. Here is the source code :

import java.lang.String;
import java.io.*;
import java.util.*;

public class vowels{

public static void main(String args[])throws IOException{
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter New String to Check :");
String text = bf.readLine();
int cnt = 0;
for (int a = 0; a < text.length(); a++) {
char b = text.charAt(a);
if (b=='a' || b=='e' || b=='i' || b=='o' || b=='u') {
cnt++;
}
}
System.out.println("Total Vowels are" + " : " + cnt);
}
}

How to Create Checkbox in Java Swing?

2008-06-17T01:28:00.000-07:00

What is Check Box?

A check box or tick box is a graphical user interface element that allow or permits user to make selections from the options. User can select more than one item or element.

The given example will explain you how to create check box in java swing. It is created in java by creating the instance of JCheckBo class. Here is the check box program :

public class CreateCheckBox{
public static void main(String[] args){
JFrame frame = new JFrame("The Check Box Example");
JCheckBox chk = new JCheckBox("Check Box 1");
JCheckBox chk = new JCheckBox("Check Box 2");
JCheckBox chk = new JCheckBox("Check Box 3");
frame.add(chk);
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

Java String Trim Example

2008-05-27T06:51:00.000-07:00

The string trim() method remove the blank spaces from the left and right in the given string.

Here is the example how to remove blank spaces :

import java.lang.*;
public class StringTrim{
public static void main(String[] args) {
System.out.println("Source code of String Trim Method");
String str = " blankspaces ";
System.out.println("Entered String :" + str);
System.out.println("Output of the Program :" +str.trim());
}
}

Display Time in JSpinner : Swing Examples

2008-04-18T00:20:00.000-07:00

Spinner allow user to select and type the value from a range of values. It has no drop-down list and this reason it is different to combo box. Here is the example to display time in JSpinner and also edit the time :

import javax.swing.*;
import java.awt.*;
import java.util.*;

public class ShowTimeJSpinner{
public static void main(String[] args) {
ShowTimeJSpinner h = new ShowTimeJSpinner();
}

public ShowTimeJSpinner(){
JFrame frame = new JFrame("JSpinner Time Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Date date = new Date();
SpinnerDateModel sm = new SpinnerDateModel(date, null, null, Calendar.HOUR_OF_DAY);
JSpinner spinner = new JSpinner(sm);
JSpinner.DateEditor de = new JSpinner.DateEditor(spinner, "hh:mm");
spinner.setEditor(de);
frame.add(spinner,BorderLayout.NORTH);
frame.setSize(100,100);
frame.setVisible(true);
}
}

How to Create Combo Box : Java Swing Example

2008-03-29T03:25:00.000-07:00

You will learn how to insert combo-box using Swing in Java. Combox box is used display item in drop down list. It provides option to select an item from the drop down. The basic difference between combo box and list box is that user cannot select multiple item from combo-box but it can be possible in list box.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class ComboBox{
JComboBox combo;
JTextField txt;
public static void main(String[] args) {
ComboBox b = new ComboBox();
}

public ComboBox(){
String course[] = {"India","Germany","America","Russia"};
JFrame frame = new JFrame("Creating a JComboBox Component");
JPanel panel = new JPanel();
combo = new JComboBox(course);
combo.setBackground(Color.gray);
combo.setForeground(Color.red);
txt = new JTextField(10);
panel.add(combo);
panel.add(txt);
frame.add(panel);
combo.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent ie){
String str = (String)combo.getSelectedItem();
txt.setText(str);
}
});
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400,400);
frame.setVisible(true);
}
}

Maximize a Frame using Swing

2008-03-20T02:00:00.000-07:00

In this program, you will learn how to maximize a frame using setMaximizedBounds() to set the bounds for a maximized frame. Here is the source code :

import java.awt.*;
import javax.swing.*;

public class SwingSetBounds{
public static void main(String[] args){
JFrame frame = new JFrame();
Rectangle bounds = new Rectangle(0, 0, 500, 500);
frame.setMaximizedBounds(bounds);
frame.setSize(400, 400);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Print Triangle using "*"

2008-03-03T01:55:00.000-08:00

This example is for the beginners. If you want to draw a traingle using "*" then use the code given below to print star in triangle shape :

import java.io.*;

class startriangle{
public static void main(String[] args) {
try{
BufferedReader object = new BufferedReader(new InputStreamReader(System.in));
System.out.println("enter the number");
int a= Integer.parseInt(object.readLine());
for (int i=1; i<'a;i++ ){
for (int j=1; j<=i;j++ ){
System.out.print("*");
}
System.out.println("");
}
}
catch(Exception e){}
}
}

Swing Tutorials : Swing Toolbar Example

2008-02-27T00:00:00.000-08:00

Have you see some small icons on top in Microsoft Word, Excel or other application. It is known as shortcut toolbar. Here is the example how to create toolbar using Java Swing :

import javax.swing.*;
import java.awt.*;

public class ToolbarExample{
public static void main(String[] args) {
JFrame frame = new JFrame("Toolbar Example Using Java Swing");
JToolBar toolbar = new JToolBar("toolBar", JToolBar.HORIZONTAL);
JButton cutbutton = new JButton(new ImageIcon("cut.gif"));
toolbar.add(cutbutton);
JButton copybutton = new JButton(new ImageIcon("copy.gif"));
toolbar.add(copybutton);
JButton pastebutton = new JButton(new ImageIcon("paste.gif"));
toolbar.add(pastebutton);
frame.getContentPane().add(toolbar,BorderLayout.NORTH);
frame.setUndecorated(true);
frame.getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500,400);
frame.setVisible(true);
}
}

Java Example : Sum of Two Numbers

2008-02-25T03:23:00.000-08:00

A very simple example to add 2 numbers. Use Integer.parseInt to convert the value in integer. By default it will consider the value as string.

public class AddNumbers{
public static void main(String[] args) {
System.out.println("Addition of two numbers!");
int a = Integer.parseInt(args[0]);
int b = Integer.parseInt(args[1]);
int sum = a + b;
System.out.println("Sum: " + sum);
}
}

Remove Title Bar : Java Swing Code

2008-02-22T21:42:00.000-08:00

This java swing example explain you how to remove title bar from the frame. Here is the example code :

import javax.swing.*;
public class RemoveTitleFrame{
public static void main(String[] args) {
JFrame frame = new JFrame(Frame With No Title Bar);
frame.setUndecorated(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400,400);
frame.setVisible(true);
}
}

Java : List Prime Numbers between 1 to Given Number

2008-02-18T20:55:00.000-08:00

This program find the even numbers between 1 to the number enter by user :

import java.io.*;
class AllEvenNum{
public static void main(String[] args) {

try{

BufferedReader br1 = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a Number : ");
int num = Integer.parseInt(br1.readLine());
System.out.println("Even Numbers are:");
for (int i=1;i <=num ; i++){
if(i%2==0 ){
System.out.print(i+",");
}
}
}
catch(Exception e){}
}
}

Table of a Given Number : Java Example

2008-02-11T02:21:00.000-08:00

This example explain how to print table of a given number. This is useful example of a java program for the beginners using while loop. We can also use for loop to print table :

Tableexample{
public static void main(String[] args) {
int a=5, b=1;
System.out.println("table of "+a+"= ");
while(b<=10){
int c = a*b;
System.out.println(c);
b = b+1;
}
}
}

Check a Number : Even or Odd?

2008-02-07T22:27:00.000-08:00

A very simple program to find whether a number is odd or even. As we have taken 4 to check whether it is even or not. It is even because when we divide it by 2 then the reminder will be 0.

class Evenodd
{
public static void main(String args[])
{
int a = 4;
if((a % 2) == 0)
System.out.print("Number is even");
else
System.out.println("Number is odd");

}
}

Java Swing Example

2008-01-15T21:40:00.001-08:00

A part of Sun Microsystems Java Foundation classes (JFC) is a widget toolkit for providing a graphical user interface. It consists of many tools including boxes, combo box, list box, buttons, dialog boxes, tables etc.

It is very interesting part of Java programming. It is the favorite topic of all the java programmers. We can customize the components and use it according to our requirements. Lets start with first program :

This program explain you how to create text area using Java swing. Here we are using javax.swing package to create GUI component. The text area will be created on panel in the frame :

import javax.swing.*;
public class TextAreaCode {
public static void main(String[] args){
JFrame frame= new JFrame("TextArea-Frame Program");
JPanel panel=new JPanel();
JTextArea jt= new JTextArea("TextArea Example",4,20);
frame.add(panel);
panel.add(jt);
frame.setSize(250,250);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Click Here for More example on Java Swing

Popup Menu in Java

2008-01-08T04:21:00.000-08:00

It is very interesting java program using java awt. Here is the program code to create popup menu when your press right mouse button.

import javax.swing.*;

import java.awt.event.*;

public class PopUpMenu{

JPopupMenu Pmenu;
JMenuItem menuItem;

public static void main(String[] args) {

PopUpMenu p = new PopUpMenu();

}

public PopUpMenu(){

JFrame frame = new JFrame("Popup Menu Example");

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Pmenu = new JPopupMenu();

menuItem = new JMenuItem("New");

Pmenu.add(menuItem);

menuItem = new JMenuItem("Open");

Pmenu.add(menuItem);

menuItem = new JMenuItem("Save");

Pmenu.add(menuItem);

menuItem = new JMenuItem("Cut");

Pmenu.add(menuItem);

menuItem = new JMenuItem("Paste");

Pmenu.add(menuItem);

menuItem.addActionListener(new ActionListener(){

public void actionPerformed(ActionEvent e){}

});

frame.addMouseListener(new MouseAdapter(){

public void mouseReleased(MouseEvent Me){

if(Me.isPopupTrigger()){

Pmenu.show(Me.getComponent(), Me.getX(), Me.getY());

}

}

});

frame.setSize(400,400);

frame.setVisible(true);

}

Prime Number Program : Java Programming

2007-12-04T21:45:00.001-08:00

This program explain you how to check the number is prime or not if user input the value from keyboard. Here is the source code :

import java.io.*;

class PrimeNumber {

public static void main(String[] args) throws Exception{

int i;

BufferedReader bf = new BufferedReader(

new InputStreamReader(System.in));

System.out.println("Enter number to Check:");

int num = Integer.parseInt(bf.readLine());

System.out.println("Prime number: ");

for (i=1; i < num; i++ ){

int j;

for (j=2; j<i; j++){

int n = i%j;

if (n==0){

break;

}

}

if(i == j){

System.out.print(" "+i);

}

}

}

}

Explanation : public static void main(String args[])

2007-11-29T22:15:00.000-08:00

What is the work of public static void main(String args[]) method in Java. Here is the explanation :

public : The public method can be accessed outside the class
static : We must have an instance to access the class method.
void : There is no need by application to return value. JVM launcher do this with it exists.
main() : It is the entry point for the java application.
String args[] : It holds optional arguments passed to the class.

First Program in Java

2007-11-27T21:04:00.000-08:00

Before writing java code, please be careful when you write the java code because it is case sensitive language. I will explain later about "String[] args".

class HelloWorld {

public static void main(String[] args){

System.out.println("My First Program:Hello World!");

}

Introduction : Java Programming

2007-11-22T22:09:00.000-08:00

Java Language :

It is high-level object-oriented programming language developed by Sun Microsystems in 1995. It is very similar to C++. It was used for the project set top box, was created by James Gosling in 1991. It is the modified from the language Oak. Oak was unsuccessful in the market. So Sun modified this language and changed its name to Java.

It is very one of the popular programming language because of platform independent nature and used in both computer and electronic devices. Platform independent means write once and run anywhere, only Java Virtual Machine needed to run Java program on any platform.