Package in Java

// A simple package

package MyPack;

public class Balance{
    String name;
    double bal;

public Balance(String n, double b){
    this.name=n;
    this.bal=b;
    }

public void show(){
    if(bal<0)
    System.out.print("LESS THAN ZERO BALANCE -->");
    System.out.println(name +": $" +bal);
    } 
}

-------------------------------------------------------------------------------------------------------------------
import MyPack.Balance;
 
class AccountBalance{
    public static void main(String args[]){
        Balance current[] = new Balance[3];
       
        current[0] = new Balance("SAIKUMAR S", 502.53);
        current[1] = new Balance("RAJESH M", 268.06);
        current[2] = new Balance("MURALI S ", -12.33);
       
        for (int i=0;i<3;i++)
        current[i].show();
        }
}//For Compilation javac -d . Balance.java (because package)

javac AccountBalance.java

java AccountBalance

Static members in java

 class staticdemo{
int objno;
static int objcnt;

void hitcount(){
objno = ++objcnt;
}

void showhits(){
System.out.println("This page has been hit for :"+objcnt);
}

void showposition(){
System.out.println("client"+objno +"/" +objcnt);
}
}
public class Static {

    public static void main(String[] args) {
    staticdemo s = new staticdemo();
    staticdemo t = new staticdemo();
    staticdemo v = new staticdemo();
  
    s.hitcount();
    t.hitcount();
    v.hitcount();
    v.showhits();
  
    s.showposition();
    t.showposition();
    v.showposition();
    }
}

Method Overloading in java program

class Test{
int area(int i){
return i*i;
}

int area(int a, int b){
return a*b;
}

}
public class MethodOverloading {

        public static void main(String[] args) {
   
            Test t = new Test();
            int area;
            area = t.area(5); 
          
            System.err.println("Area of a square is :"+area);
          
            area = t.area(5,6);
            System.out.println("Area of a rectangle is :"+area);
    }
}

Multiple if else statement using java(if stmt else condition)

import java.util.*;

public class Condition {

    public static void main(String[] args) {
      int a[]= new int[1] ;
            Scanner sc=new Scanner(System.in);
            System.out.println("Please enter elements between 0 and 6");
            for(int j=0;j<1;j++)
                a[j] = sc.nextInt();

            for(int j=0;j<1;j++)
                if(a[j]==0)
                {
                System.out.println("Sunday!");
                 break;}
                else if(a[j]==1)
                {
                    System.out.println("Monday!");
                 break;}
                else if(a[j]==2)
                {
                System.out.println("Tuesday!");
                 break;}
                else if(a[j]==3)
                {
                    System.out.println("Wednesday!");
                 break;}
                else if(a[j]==4)
                {
                System.out.println("Thursday!");
                break; }
                 else if(a[j]==5)
                {
                    System.out.println("Friday!");
                 break;}
                else if(a[j]==6)
                {
                System.out.println("Saturday!");
                 break;}
                else
                {
                System.out.println("Sorry Invallid option! Enter the number between the range 0 to 6");
              break;  }

                         
    }
}

 

 Java button applet program

import java.awt.*;
public class ButtonActionsTest extends java.applet.Applet {

public void init() {

setBackground(Color.white);
add(new Button("Red"));
add(new Button("Blue"));
add(new Button("Green"));
add(new Button("White"));
add(new Button("Black"));
}
public boolean action(Event evt, Object arg) {
if (evt.target instanceof Button)
changeColor((String)arg);
return true;
}
void changeColor(String bname) {
if (bname.equals("Red")) setBackground(Color.red);
else if (bname.equals("Blue")) setBackground(Color.blue);
else if (bname.equals("Green")) setBackground(Color.green);
else if (bname.equals("White")) setBackground(Color.white);
else setBackground(Color.black);
}
}

Inheritance Example Color box in java

import java.awt.Graphics; 

import java.awt.Color;

 public class ColorBoxes extends java.applet.Applet {

public void paint(Graphics g) {
 int rval, gval, bval;

 for (int j = 30; j < (this.size().height -25); j += 30)
 for (int i = 5; i < (this.size().width -25); i+= 30) {
 rval = (int)Math.floor(Math.random() * 256);
 gval = (int)Math.floor(Math.random() * 256);
 bval = (int)Math.floor(Math.random() * 256);

 g.setColor(new Color(rval,gval,bval));
 g.fillRect(i,j,25,25);
 g.setColor(Color.black);
 g.drawRect(i-1,j-1,25,25);
 }
 }
 }

Program for Vowels And Consonants

public class VowelsAndConsonants {
  public static void main(String[] args) {
    for(int i = 0; i < 100; i++) {
      char c = (char)(Math.random() * 26 + 'a');
      System.out.print(c + ": ");
      switch(c) {
      case 'a':
      case 'e':
      case 'i':
      case 'o':
      case 'u':
                System.out.println("vowel");
                break;
      case 'y':
      case 'w':
                System.out.println(
                  "Sometimes a vowel");
                break;
      default:
                System.out.println("consonant");
      }
    }
  }
}

Label in Java

import java.awt.*;
public class ColorTest extends java.applet.Applet {
ColorControls RGBcontrols, HSBcontrols;
Canvas swatch;
public void init() {
Color theColor = new Color(0,0,0);
float[] HSB = Color.RGBtoHSB(theColor.getRed(),
theColor.getGreen(), theColor.getBlue(),
(new float[3]));
setLayout(new GridLayout(1,3,10,10));
// The color swatch
swatch = new Canvas();
swatch.setBackground(theColor);
// the control panels
RGBcontrols = new ColorControls(this,"Red", "Green", "Blue",theColor.getRed(), theColor.getGreen(),theColor.getBlue());
HSBcontrols = new ColorControls(this,"Hue", "Saturation", "Brightness",(int)(HSB[0] * 360), (int)(HSB[1] * 100),(int)(HSB[2] * 100));
add(swatch);
add(RGBcontrols);
add(HSBcontrols);
}
public Insets insets() {
return new Insets(10,10,10,10);
}
void update(ColorControls in) {
Color c;
String v1 = in.f1.getText();
String v2 = in.f2.getText();
String v3 = in.f3.getText();
if (in == RGBcontrols) { // change to RGB
c = new Color(Integer.parseInt(v1),
Integer.parseInt(v2),
Integer.parseInt(v3));
swatch.setBackground(c);

float[] HSB = Color.RGBtoHSB(c.getRed(),c.getGreen(),
c.getBlue(), (new float[3]));
HSB[0] *= 360;
HSB[1] *= 100;
HSB[2] *= 100;
HSBcontrols.f1.setText(String.valueOf((int)HSB[0]));
HSBcontrols.f2.setText(String.valueOf((int)HSB[1]));
HSBcontrols.f3.setText(String.valueOf((int)HSB[2]));
}
else { // change to HSB
int f1 = Integer.parseInt(v1);
int f2 = Integer.parseInt(v2);
int f3 = Integer.parseInt(v3);
c = Color.getHSBColor((float)f1 / 360,
(float)f2 / 100, (float)f3/100);
swatch.setBackground(c);
RGBcontrols.f1.setText(String.valueOf(c.getRed()));
RGBcontrols.f2.setText(String.valueOf(
c.getGreen()));
RGBcontrols.f3.setText(String.valueOf(c.getBlue()));
}
}
}
class ColorControls extends Panel {
TextField f1, f2, f3;
ColorTest outerparent;
ColorControls(ColorTest target,
String l1, String l2, String l3,
int v1, int v2, int v3) {
this.outerparent = target;
setLayout(new GridLayout(3,4,10,10));
f1 = new TextField(String.valueOf(v1),10);
f2 = new TextField(String.valueOf(v2),10);
f3 = new TextField(String.valueOf(v3),10);
add(new Label(l1, Label.RIGHT));
add(f1);
add(new Label(l2, Label.RIGHT));
add(f2);
add(new Label(l3, Label.RIGHT));
add(f3);
}
public Insets insets() {
return new Insets(10,10,0,0);
}
public boolean action(Event evt, Object arg) {
if (evt.target instanceof TextField) {

this.outerparent.update(this);

// retrue true;
}
// else return false;
}
}

Swings in Java for a Label

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

/* <applet code="JLabelDemo" width=355 height=200>
</applet>
*/

public class JLabelDemo extends JApplet{

public void init() {
// Get content pane
Container contentPane = getContentPane();

// Create an icon
ImageIcon ii = new ImageIcon("sateesh.jpg");

// Create a label
JLabel jl = new JLabel ("AVUL KALAM", ii, JLabel.CENTER);

// Add label to the content pane
contentPane.add(jl);
}
}

Simple Operators in Java Break And Continue 

public class BreakAndContinue {

  public static void main(String[] args) {

 for(int i = 0; i < 100; i++) {
      if(i == 74) break; // Out of for loop
      if(i % 9 != 0) continue; // Next iteration
      System.out.println(i);
    }
    int i = 0;
    // An "infinite loop":
    while(true) {
      i++;
      int j = i * 27;
      if(j == 1269) break; // Out of loop
      if(i % 10 != 0) continue; // Top of loop
      System.out.println(i);
    }
  }
}

Conditional operator ?: (Ternary operator) in JAVA

class BigNo
{
     public static void main (String args[])
    {

          int a = Integer.parseInt(args[0]);
          int b = Integer.parseInt(args[1]);
          int c = Integer.parseInt(args[2]);
          int x = (a>b)?(a>c?a:c):(b>c?b:c);

          System.out.println(+x);
      }
}

How to Read values through(via) keyboard using Scanner

import java.util.*;

public class Array

{

       public static void main(String args[])

      {

         int[] a=new int[6];

         Scanner sc=new Scanner(System.in);

         System.out.println("Please enter elements...");

         for(int j=0;j<6;j++)

         a[j]=sc.nextInt();

         System.out.println("Array elements are : ");

         for (int i=0;i<a.length;i++)

         System.out.println(a[i]);

       }

}

Program on how to copy data from one array to another array

public class CopyArray {
    public static void main(String[] args) {
        int array1[]= {2,3,4,5,8,9};
        int array2[] = new int[6];
        System.out.println("array:");
        System.out.print("[");
        for (int i=0; i<array1.length; i++){
            System.out.print(" "+array1[i]);
        }
        System.out.print("]");
        System.out.println("\narray1:");
        System.out.print("[");
        for(int j=0; j<array1.length; j++){
            array2[j] = array1[j];
            System.out.print(" "+ array2[j]);
        }
        System.out.print("]");
    }
}

Java program for an Array 

import java.util.*;

public class  ArrayDemo{
  public static void main(String[] args){
  int num[] = {50,20,45,82,25,63};
  int l = num.length;
  int i,j,t;
  System.out.print("Given number : ");
  for (i = 0;i < l;i++ ){
  System.out.print("  " + num[i]);
  }
  System.out.println("\n");
  System.out.print("Accending order number : ");
  Arrays.sort(num);
    for(i = 0;i < l;i++){
  System.out.print("  " + num[i]);
  }
  }
}

JAVA Program for Constructor

class BoxDemo {
  double width;
  double height;
  double depth;
 
  // this is a constructor for Box
    BoxDemo(){
    System.out.println("Constructing BoxDemo");
    width =10;
    height =10;
    depth =10;
    }
    //compute and return value
    double volume(){
    return width*height*depth;
    }
  }

class  Box{
    public static void main(String[] args) {
        BoxDemo mybox = new BoxDemo();
       
        double vol;
        // get the volume of the box
       
        vol = mybox.volume();
       
        System.out.println("VOLUME IS "+vol);
      }
}

// output : Constructing BoxDemo
//             VOLUME IS 1000.0

 

 Constructor in JAVA (Parametrized) 

class Box{
double width;
double height;
double depth;
//this is the constructor for Box

        Box(double w, double h, double d)
        {
        width = w;
        height = h;
        depth = d;
        }
// compute and return value
        double volume()
        {
        return width*height*depth;
        }
}

    class BoxParConst{
    public static void main(String args[]){
// declare allocate and initialize Box objects

    Box mybox1 = new Box(10,20,15);
    Box mybox2 = new Box(3,6,9);
   
    double vol;
   
// get the volume of first box
   
    vol = mybox1.volume();
    System.out.println("Volume of the first Box is:"+vol);

// get the volume of second box

    vol = mybox2.volume();
    System.out.println("Volume of the second Box is:"+vol);
   
    }
}

Program demo on How to Read a value through key board and print the factorial of a given number

import java.io.*;

class Fact{
    public static void main(String args[]){

    BufferedReader Br = new BufferedReader(new InputStreamReader(System.in));
try{

    int fact=1;

        System.out.println("Enter a number to find out factorial of a given number: \n" );
        String nu = Br.readLine();
        int n = Integer.parseInt(nu);

        for(int i=2;i<=n;i++)
        {
            fact=fact*i;   
       
        }
   
            System.out.println("Factorial of a given number is:" +fact);

    }catch (IOException err){
            System.out.println("Error reading line");
            }
       
    }
}

 Program to convert a string from lower case to upper case

import java.lang.*;
import java.io.*;
public class key
{
public static void main(String args[])throws IOException
{
try
{
   BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
   System.out.println("enter the input from the key board");
   String str=br.readLine();
   System.out.println("Data enterd is "+str.toUpperCase());
   }
   catch(Exception e)
   {
   System.out.println(e);
   }
   }
   } 

 Switch case simple program

class SwitchDemo
{
public static void main(String args[])
{
 int month=Integer.parseInt(args[0]);
switch(month)
{
case 1: System.out.println("January");break;
case 2: System.out.println("February");break;
case 3: System.out.println("March");break;
case 4: System.out.println("April");break;
case 5: System.out.println("May");break;
case 6: System.out.println("June");break;
case 7: System.out.println("July");break;
case 8: System.out.println("August");break;
case 9: System.out.println("September");break;
case 10: System.out.println("October"); break;
case 11: System.out.println("November"); break;
case 12: System.out.println("October"); break;

default: System.out.println("Sorry ! invallied choice");break;
}
}
}

JAVA Program for Combo Box using applet . 

Attach the image part also using some image file

//JComboBox Demo
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/*
<applet code="JComboBoxDemo" width=300 height=100>
</applet>
*/

public class JComboBoxDemo extends JApplet
implements ItemListener {

JLabel jl;
ImageIcon Flowers, Koala, Desert, Penguins, sateesh;

public void init(){
// Get content pane
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());

// Create a Combo box and add it
//to the pane
JComboBox jc = new JComboBox();
jc.addItem("Flowers");
jc.addItem("Koala");
jc.addItem("Desert");
jc.addItem("Penguins");
jc.addItem("sateesh");
jc.addItemListener(this);
contentPane.add(jc);

//Create label
jl = new JLabel(new ImageIcon("Flowers.gif")); //attach image here
contentPane.add(jl);
}

public void itemStateChanged(ItemEvent ie) {
String s = (String)ie.getItem();
jl.setIcon(new ImageIcon(s +".gif"));
}
}

 Program to create Check box in Java

This java program is used for displaying a clicked item in a text box

compiling: javac JCheckBoxDemo.java
Run: appletviewer JCheckBoxDemo.java

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

/*

<applet code="JCheckBoxDemo" width=500 height=60>
</applet>

*/

public class JCheckBoxDemo extends JApplet
implements ItemListener {
JTextField jtf;

public void init(){

//Get content pane
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());

// Create icons
 ImageIcon normal = new ImageIcon ("normal.gif");
 ImageIcon rollover = new ImageIcon ("rollover.gif");
 ImageIcon selected = new ImageIcon ("selected.gif");

// Add check boxes to the content pane
JCheckBox cb = new JCheckBox("C", normal);
cb.setRolloverIcon(rollover);
cb.setSelectedIcon(selected);
cb.addItemListener(this);
contentPane.add(cb);

cb = new JCheckBox("C++", normal);
cb.setRolloverIcon(rollover);
cb.setSelectedIcon(selected);
cb.addItemListener(this);
contentPane.add(cb);

cb = new JCheckBox("Java", normal);
cb.setRolloverIcon(rollover);
cb.setSelectedIcon(selected);
cb.addItemListener(this);
contentPane.add(cb);

cb = new JCheckBox("Perl", normal);
cb.setRolloverIcon(rollover);
cb.setSelectedIcon(selected);
cb.addItemListener(this);
contentPane.add(cb);

cb = new JCheckBox("VB", normal);
cb.setRolloverIcon(rollover);
cb.setSelectedIcon(selected);
cb.addItemListener(this);
contentPane.add(cb);


// Add text field to the content pane
jtf = new JTextField(15);
contentPane.add(jtf);
}

public void itemStateChanged(ItemEvent ie) {
JCheckBox cb = (JCheckBox)ie.getItem();
jtf.setText(cb.getText());
}
}

Java demo program for on Button using Applet

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

/*
<applet code="JRadioButtonDemo" width=500 height=50>
</applet>
*/

public class JRadioButtonDemo extends JApplet
implements ActionListener {
JTextField jtf;

public void init(){

// Get content pane
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());

// ADD radio buttons to content pane
JRadioButton b1 = new JRadioButton("B.Sc");
b1.addActionListener(this);
contentPane.add(b1);

JRadioButton b2 = new JRadioButton("M.Sc");
b2.addActionListener(this);
contentPane.add(b2);

JRadioButton b3 = new JRadioButton("B.Tech");
b3.addActionListener(this);
contentPane.add(b3);

JRadioButton b4 = new JRadioButton("M.Tech");
b4.addActionListener(this);
contentPane.add(b4);

JRadioButton b5 = new JRadioButton("M.C.A");
b5.addActionListener(this);
contentPane.add(b5);

// Define a button group
ButtonGroup bg = new ButtonGroup();
bg.add(b1);
bg.add(b2);
bg.add(b3);
bg.add(b4);
bg.add(b5);

// Add text field to the content pane
jtf = new JTextField(15);
contentPane.add(jtf);
}
public void actionPerformed(ActionEvent ae){
jtf.setText(ae.getActionCommand());
}
}

Java text field or you ca say a Text Box

compilation: javac JTextFieldDemo.java
Run: appletviewer JTextFieldDemo.java

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

/* <applet code="JTextFieldDemo" width=200 height=50>
</applet>
*/

public class JTextFieldDemo extends JApplet{

public  void init() {

// Get content pane
Container contentPane = getContentPane();

//Creating a Text filed
JTextField jtf = new JTextField(JTextField.CENTER);


// Add text field to content pane
contentPane.add(jtf);

}
}

 

 Java program on Harmonic Series(HM) 

class Harmonic
{
public static void main (String args[])
{
int k,n=3;
double i=1,s,f=0;
while(i<=n)
{
s=1/i;
f=f+s;
i++;
}
for(k=1;k<=n;k++)
{
System.out.print("1/i"+k);
System.out.print("   ");
System.out.print(" + ");
System.out.print("  ");
}
System.out.print("-----------");
System.out.print("="+f);
}
}

Program for demo on Label and Image in Single code

This swing java program is used for displaying image, label in an applet.

Place a required picture in a folder, copy and paste the following code in a note pad and
save as "JLabelDemo.java" as the file name. Note that picture and java file must be stored
in the same folder.

compilation: javac JLabelDemo.java
run: appletviewer JLabelDemo.java

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

/* <applet code="JLabelDemo" width=355 height=200>
</applet>
*/

public class JLabelDemo extends JApplet{

public void init() {
// Get content pane
Container contentPane = getContentPane();

// Create an icon
ImageIcon ii = new ImageIcon("sateesh.jpg");

// Create a label
JLabel jl = new JLabel ("SATEESH.BAGADHI", ii, JLabel.CENTER);

// Add label to the content pane
contentPane.add(jl);
}
} 

 J applet for displaying a name

import java.awt.Graphics;
 import java.awt.Font;
 import java.awt.Color;

 public class MoreHelloApplet extends java.applet.Applet {

 Font f = new Font("TimesRoman",Font.BOLD,36);
 String name;

 public void init() {
 this.name = getParameter("name");
 if (this.name == null)
this.name = "Avul Kalam";

 this.name = "Hello  " + this.name + "!";
    }

 public void paint(Graphics g) {
 g.setFont(f);
 g.setColor(Color.red);
 g.drawString(this.name, 5, 50);
 }
 }

Concept of Class Method and Object in JAVA

class Student{

    int no=10;    // data members

    void display(){  // method
        System.out.println("Hai!");
    }
}

class Main_Student{
public static void main(String args[]){
   
    Student s = new Student(); //object s for Student class
   
    System.out.println("Student number is:" +s.no);
    s.display();
    System.out.println("This is main class!");   
    }
}

Java Program for Tabbed Pane in Java using applet 

File name JTabbedPaneDemo.java

 PROGRAM

import javax.swing.*;
/*
<applet code="JTabbedPaneDemo" width=400 height=100>
</applet>
 */
public class JTabbedPaneDemo extends JApplet {
public void init() {
JTabbedPane jtp = new JTabbedPane();
jtp.addTab("Cities", new CitiesPanel());
jtp.addTab("Colors", new ColorsPanel());
jtp.addTab("Flavors", new FlavorsPanel());
getContentPane().add(jtp);
}
}

class CitiesPanel extends JPanel  {
public CitiesPanel()  {
JButton b1 = new JButton("New York");
add(b1);
JButton b2 = new JButton("London");
add(b2);
JButton b3 = new JButton("Hong Kong");
add(b3);
JButton b4 = new JButton("Tokyo");
add(b4);
}
}

class ColorsPanel extends JPanel  {
public ColorsPanel()  {
JCheckBox cb1 = new JCheckBox("RED");
add(cb1);
JCheckBox cb2 = new JCheckBox("Green");
add(cb2);
JCheckBox cb3 = new JCheckBox("Blue");
add(cb3);
}
}

class FlavorsPanel extends JPanel {
public FlavorsPanel() {
JComboBox jcb = new JComboBox();
jcb.addItem("Vanilla");
jcb.addItem("Chocolate");
jcb.addItem("Strawberry");
add(jcb);
}
}

Compilation and Execution

  

  

Java program demo on tool tip

  //Java Core Package
import javax.swing.*;
//Java Extension Package
import java.awt.*;

public class JavaApplication2 extends JFrame {
   
    //Initializing JButton
    private JButton button;

    //Setting up GUI
    public JavaApplication2() {
       
        //Setting up the Title of the Window
        super("Add ToolTipText on JButton");

        //Set Size of the Window (WIDTH, HEIGHT)
        setSize(250,100);

        //Exit Property of the Window
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Constructing JButton
        button = new JButton("Place The Cursor Here...");
       
        //Setting or Adding ToolTipText on JButton
        button.setToolTipText("My First ToolTipText on JButton");

        //Setting up the container ready for the components to be added.
        Container pane = getContentPane();
        setContentPane(pane);
       
        //Setting up the container layout
        FlowLayout flow = new FlowLayout(FlowLayout.CENTER);
        pane.setLayout(flow);

        //Adding the JButton component to the container
        pane.add(button);

        /**Set all the Components Visible.
         * If it is set to "false", the components in the container will not be visible.
         */
        setVisible(true);
    }
   
    //Main Method
    public static void main (String[] args) {
        JavaApplication2 ttt = new JavaApplication2();
    }
}

JAVA IO for displaying student details using fopen flcose

import java.io.*;

class Student{

public static void main(String args[]){

    InputStreamReader is = new InputStreamReader(System.in);
    BufferedReader br = new BufferedReader(is);
   
    System.out.print("Welcome to java");
   
    try{
   
        System.out.println("Enter Student Name:");
   
        String Name = br.readLine();
     
        System.out.println("Enter Student Number:");
       
        String No = br.readLine();
       
        System.out.println("Enter Student class:");
       
        String Clas = br.readLine();
   
    System.out.println(" Hi "+Name +" your no is: "+ No +", you are studying "+Clas +"!");
        }
       
    catch (IOException Err) {
   
    System.out.print("Error in reading Line!");
    }
   
    catch(NumberFormatException Err){
    System.out.print("Error in Number format conversion!");
    }
    }
}

  

Jdbc(Java Database Connectivity) Odbc(Open Database Conectiy) program using MS-Access database (4 Drivers)

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

class Myframe extends JFrame implements ActionListener
 {
   JLabel lno,lname;
   JTextField tno,tname;
   JButton insert,view,update,search,nxt,pre,lst,frt,clr,dlt,exit;

   Connection cn;
   Statement st;
   ResultSet rs;
   Container conpane;
   Myframe()
   {

     lno=new JLabel("Eno");
     lname=new JLabel("Ename");

     tno=new JTextField(6);
     tname=new JTextField(15);

     insert=new JButton("Insert");
     view=new JButton("View");
     nxt=new JButton("Next");
     pre=new JButton("Previous");
     lst=new JButton("Last");
     frt=new JButton("First");
     clr=new JButton("Clear");
     dlt=new JButton("Delete");
     update=new JButton("Update");
     search=new JButton("Search");
     exit=new JButton("Exit");

     conpane = getContentPane();

     JPanel txtPanel,btnPanel;

    txtPanel = new JPanel();
    btnPanel = new JPanel();
     //setLayout(new GridLayout(2,2));
        conpane.add(txtPanel,BorderLayout.NORTH);
        conpane.add(btnPanel,BorderLayout.CENTER);
     txtPanel.add(lno);
     txtPanel.add(tno);

     txtPanel.add(lname);
     txtPanel.add(tname);

     btnPanel.add(insert);
     btnPanel.add(view);
     btnPanel.add(nxt);
     btnPanel.add(pre);
     btnPanel.add(lst);
     btnPanel.add(frt);
     btnPanel.add(clr);
     btnPanel.add(dlt);
     btnPanel.add(update);
     btnPanel.add(search);
     btnPanel.add(exit);

     insert.addActionListener(this);
     view.addActionListener(this);
     nxt.addActionListener(this);
     pre.addActionListener(this);
     lst.addActionListener(this);
     frt.addActionListener(this);
     clr.addActionListener(this);
     dlt.addActionListener(this);
     update.addActionListener(this);
     search.addActionListener(this);
     exit.addActionListener(this);

     try
                     {

                      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
                      cn=DriverManager.getConnection("jdbc:odbc:employeedsn");
                      st=cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
                     rs=st.executeQuery("select * from emp");
                     rs.next();

                }catch(Exception e){}
    }

    public void actionPerformed(ActionEvent a)

    {

    try
      {


         if(a.getSource()==search)
           {

            dbOpen();
             String str = JOptionPane.showInputDialog(null, "Enter empno : ");

            rs=st.executeQuery("select * from emp where eno="+str+"");

            rs.next();
            setText();
           }

         if(a.getSource()==update)
           {
             dbOpen();
             int ueno=Integer.parseInt(tno.getText());
             String uname=(tname.getText());
             st.executeUpdate("UPDATE emp SET eno=" + ueno +",ename='" + tname.getText() + "' WHERE eno="+ ueno +"  ");
             JOptionPane.showMessageDialog(null,"Record is updated");
           }
         if(a.getSource()==dlt)
            {
               int deno=Integer.parseInt(tno.getText());

               st.executeUpdate("DELETE FROM emp WHERE eno="+ deno);
               JOptionPane.showMessageDialog(null,"Record is deleted");

            dbClose();
            dbOpen();

            }
         if(a.getSource()==clr)
           {
                   tno.setText("");
                   tname.setText("");
                   rs.first();
           }

         if(a.getSource()==frt)
          {
                  rs.first();
                  setText();
           }

         if(a.getSource()==lst)
          {
                 rs.last();
                  setText();
            }

         if(a.getSource()==nxt)
          {
             if(!rs.isAfterLast())
              {
                 rs.next();
                 setText();

            }

          else
             {
                  JOptionPane.showMessageDialog(null,"Last Record");
                 rs.previous();
             }
           }
         if(a.getSource()==pre)
          {
            if(!rs.isBeforeFirst())
              {
                 rs.previous();
                 setText();
                 }
           else
            {
                 JOptionPane.showMessageDialog(null,"First Record");
                 rs.first();
            }
          }
        if(a.getSource()==insert)
        {
          int eno=Integer.parseInt(tno.getText());
          String name=(tname.getText());
         st.executeUpdate("insert into emp values("+eno+",'"+name+"')");
         JOptionPane.showMessageDialog(null,"Record inserted into database");

         dbClose();
            dbOpen();
        }

       if(a.getSource()==view)
       {
            rs.next();
            setText();
            dbClose();
            dbOpen();
       }
       if(a.getSource()==exit)
                   {
                       if(JOptionPane.showConfirmDialog(null,"Are You Sure You Want to Exit?","Confirm",JOptionPane.YES_NO_OPTION)==JOptionPane.YES_OPTION)
                       System.exit(0);
                }
    }catch(Exception e)
      {
      }
}
public void dbOpen()
    {
        try
                {
                 Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
                 cn=DriverManager.getConnection("jdbc:odbc:employeedsn");
                 st=cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
                rs=st.executeQuery("select * from emp");
                rs.next();

                }catch(Exception e){}
    }

public void setText(){
        try{
            tno.setText(rs.getString(1));
            tname.setText(rs.getString(2));
            }catch(Exception ex){}
            }

            public void dbClose()
                {
                    try{
                        st.close();
                    rs.close();
                    cn.close();
                    }catch(Exception e){}
    }
}

class jdbcdemoframe
{
    public static void  main(String s[])
    {
        Myframe f= new Myframe();
        f.setVisible(true);
        f.setTitle("Employee Information");
        f.setSize(350,250);
    }
}

DATA STRUCTURES

STACK Program using JAVA
STACK follows LIFO of FILO Last In First Out or First In Last Out
Operations PUSH(Add) POP (Delete)

import java.util.Scanner;

class Stack {

    int[] a;
    int top;

    public Stack(int n) {
        a = new int[n];
        top = -1;
    }

    public void push(int val) {
        if (top == a.length - 1) {
            System.out.println("Stack overflow...");
        } else {
            top++;
            a[top] = val;
        }
    }

    public void pop() {
        if (top == -1) {
            System.out.println("Stack underflow...");
        } else {
            System.out.println("Element popped" + a[top]);
            top--;
        }
    }

    public void display() {
        if (top == -1) {
            System.out.println("Stack empty...");
        } else {
            for (int i = top; i >= 0; i--) {
                System.out.println("Stack element: " + a[i]);
            }
        }
    }
}

public class UseStack {

    static public void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        Stack s;
        int n;
        System.out.println("Enter the size of the stack: ");
        n = sc.nextInt();
        s = new Stack(n);
        int choice;

        do {
            System.out.println("1.PUSH" + "\n" + "2.POP" + "\n" + "3.DISPLAY" + "\n" + "0.EXIT");
            System.out.println("Enter your choice");
            choice = sc.nextInt();

            switch (choice) {
                case 1:
                    int value;
                    System.out.println("Enter element to push");
                    value = sc.nextInt();
                    s.push(value);
                    break;

                case 2:
                    s.pop();
                    break;

                case 3:
                    s.display();

                case 0:
                    break;

                default:
                    System.out.println("invalid choice...");
            }
        } while (choice != 0);

    }
}

 Program in JAVA for string Sorting

import java.lang.*;

class City
{
public static void main(String args[])
{

String name[] = {"visakhapatnam","hyderabad","kolkata","mumbai","chennai","delhi","ahamdabad","calcutta","bombay"};

int size=name.length;
String temp;
    System.out.println("The total number of the strings are:" + name.length);

    for(int i=0;i<size;i++)
    {
        for(int j=i+1;j<size;j++)
        {
        if(name[j].compareTo(name[i])<0)
        {

        temp=name[i];
        name[i]=name[j];
        name[j]=temp;
        }
    }
}
    for(int i=0;i<size;i++)
    {
        System.out.println(name[i]);
    }
    }
}

Analysis of Basic Algorithm
The above algorithm doesn’t always use minimum number of colors. Also, the number of colors used sometime depend on the order in which vertices are processed. For example, consider the following two graphs. Note that in graph on right side, vertices 3 and 4 are swapped. If we consider the vertices 0, 1, 2, 3, 4 in left graph, we can color the graph using 3 colors. But if we consider the vertices 0, 1, 2, 3, 4 in right graph, we need 4 colors.





So the order in which the vertices are picked is important. Many people have suggested different ways to find an ordering that work better than the basic algorithm on average. The most common is Welsh–Powell Algorithm which considers vertices in descending order of degrees. 

How does the basic algorithm guarantee an upper bound of d+1?
Here d is the maximum degree in the given graph. Since d is maximum degree, a vertex cannot be attached to more than d vertices. When we color a vertex, at most d colors could have already been used by its adjacent. To color this vertex, we need to pick the smallest numbered color that is not used by the adjacent vertices. If colors are numbered like 1, 2, …., then the value of such smallest number must be between 1 to d+1 (Note that d numbers are already picked by adjacent vertices).

 Eight Queens
Chess composer Max Bezzel published the eight queens puzzle in 1848. Franz Nauck published the first solutions in 1850. Nauck also extended the puzzle to the n-queens problem, with n queens on a chessboard of n × n squares.

The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens threaten each other. Thus, a solution requires that no two queens share the same row, column, or diagonal. The eight queens puzzle is an example of the more general n-queens problem of placing n queens on an n×n chessboard, where solutions exist for all natural numbers n with the exception of n=2 or n=3.

a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

The only symmetrical solution (excluding rotation and reflection) to the eight queens puzzle

 

Algorithm

The following is a Pascal program by Niklaus Wirth. It finds one solution to the eight queens problem.

program eightqueen1(output);
 
var i : integer; q : boolean;
    a : array[ 1 .. 8] of boolean;
    b : array[ 2 .. 16] of boolean;
    c : array[ -7 .. 7] of boolean;
    x : array[ 1 .. 8] of integer;
 
procedure try( i : integer; var q : boolean);
    var j : integer;
    begin 
    j := 0;
    repeat 
        j := j + 1; 
        q := false;
        if a[ j] and b[ i + j] and c[ i - j] then
            begin 
            x[ i    ] := j;
            a[ j    ] := false; 
            b[ i + j] := false; 
            c[ i - j] := false;
            if i < 8 then
                begin
                try( i + 1, q);
                if not q then
                    begin 
                    a[ j] := true; 
                    b[ i + j] := true; 
                    c[ i - j] := true;
                    end
                end 
            else 
                q := true
            end
    until q or (j = 8);
    end;
 
begin
for i :=  1 to  8 do a[ i] := true;
for i :=  2 to 16 do b[ i] := true;
for i := -7 to  7 do c[ i] := true;
try( 1, q);
if q then
    for i := 1 to 8 do write( x[ i]:4);
writeln
end.