Learning Java Program

class StringDemo
{
public static void main (String args[])
{
String str = "I am vijay";
System.out.println("The string is: " + str);
System.out.println("The string in upper case: " + str.toUpperCase());
System.out.println("Length of this string: " + str.length());
System.out.println("The character at position 5: "+ str.charAt(5));
System.out.println("The index of the character y: " + str.indexOf('y'));
System.out.println("The substring from 2 to 10: " + str.substring(2, 10));
System.out.println("The index of the beginning of the substring vijay: " + str.indexOf("vijay"));
}
}

The string is: I am vijay
The string in upper case: I AM VIJAY
Length of this string: 10
The character at position 5: v
The index of the character y: 9
The substring from 2 to 10: am vijay
The index of the beginning of the substring vijay: 5

class arithmetic
{
    public static void main(String args[])
    {
        short x = 8;
        int y = 2;
        float a = 10.5f;
        float b = 6f;
        System.out.println("Addition: "+(x+y));
        System.out.println("Subtraction: "+(x-y));
        System.out.println("Multiplication: "+(x*y));
        System.out.println("Division: "+(x/y));
        System.out.println("Modulus: "+(x%y));
        System.out.println("Floating point Division: "+(a/b));
    }
}

Addition: 10
Subtraction: 6
Multiplication: 16
Division: 4
Modulus: 0
Floating point Division: 1.75

class printOdd
{
    public static void main(String args[])
    {
        for(int x=1; x<10; x=x+2)
        {
        System.out.println(x);
        }
    }
}

1
3
5
7
9

class printEven
{
    public static void main(String args[])
    {
        for(int x=0; x<10; x=x+2)
        {
        System.out.println(x);
        }
    }
}

0 

2 

4 

6 

8

for(initialization; condition; iteration) 

statement;

Program:

 

Output:

if(condition 1)
statement 1;
else if (condition 2)
statement 2;
else if (condition 3)
statement 3;

else 

statement 4;

import java.util.Scanner;
class result
{
    public static void main(String[] args)
    {
           int mark;
           Scanner s=new Scanner(System.in);
           System.out.print("Enter your mark: ");                   
           mark=s.nextInt();
           if ( mark >= 90 )
           {
            System.out.println( "Grade A" );
           }
           else if ( mark >= 80 )
           {
            System.out.println( "Grade B" );
           }
           else if ( mark >= 70 )
           {
            System.out.println( "Grade C" );
           }
           else if ( mark >= 60 )
           {
            System.out.println( "Grade D" );
           }
           else if ( mark >= 50 )
           {
            System.out.println( "Grade E" );
           }
           else if ( mark >= 40 )
           {
            System.out.println( "Grade F" );
           }
           else 
           {
            System.out.println( "Failed" );
           }    
    }
}

Enter your mark: 56 

Grade E 

Enter your mark: 10 

Failed

if(condition)
statement 1;
else
statement 2;

import java.util.Scanner;
class result
{
    public static void main(String[] args)
    {
           int mark;
           Scanner s=new Scanner(System.in);
           System.out.print("Enter your mark: ");                   
           mark=s.nextInt();
           if ( mark <= 60 )
           {
                System.out.println("Fail");
           }
            else
           {
                System.out.println("Pass");
           }
    }
}

Enter your mark: 23
Fail
Enter your mark: 56
Pass

if(condition)
statement;

import java.util.Scanner;
class result
{
    public static void main(String[] args)
    {
           int mark;
           Scanner s=new Scanner(System.in);
           System.out.print("Enter your mark: ");                   
           mark=s.nextInt();
           if ( mark >= 40 )
           {
           System.out.println("Pass");
           }
    }

}

Enter your mark: 44 

Pass

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
class palindrome
{
    public static void main(String[] args)
    {
        try
   {
            System.out.print("Enter a number: ");
  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            String num=br.readLine();
            int no=Integer.parseInt(num);
            int temp=no;
            int digit=0,ld;
            while(no!=0)
            {
                ld=no%10;
                digit=digit*10+ld;
                no=no/10;
            }
            if(temp==digit)
            {
                System.out.println("Palindrome number");
            }
            else
     {
                System.out.println("Not a palindrome number");
            }
        }
   catch (IOException | NumberFormatException ex)
   {
       }
    }
}

Enter a number: 123
Not a palindrome number

Enter a number: 12321
Palindrome number

import java.io.BufferedReader;
import java.io.InputStreamReader;
class Reverse
{
    public static void main(String[] args)
    {
        try
   {
            System.out.print("Enter string : ");
  BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            String str=in.readLine();
            for(int i=str.length()-1;i>=0;i--)
            {
              System.out.print(str.charAt(i));
            }
       }
   catch (Exception ex)
   {
      }
    }
}

Enter string : VIJAY 

YAJIV

import java.util.Scanner;
class fibonacci
{
  public static void main(String[] args)
    {
        System.out.print("Enter the number to display fibonicci series:  ");
        Scanner in=new Scanner(System.in);
        int num=in.nextInt();
        int a=0,b=1,c=0,i=0;
        while(i!=num)
        {
            System.out.println(c);
            a=b;
            b=c;
            c=a+b;
            i++;         
        }
    }
}

import java.util.Scanner;
class pyramidShape
{
 public static void main(String[] args)
   {
     System.out.print("Enter number of rows: ");
     Scanner in = new Scanner(System.in);
     int num=in.nextInt();
     for(int i=1;i<=num;i++)
     {
          for(int j=num;j>=i;j--)
          {
           System.out.print(" ");
          }
          for(int m=1;m<=i*2-1;m++)
          {
           System.out.print("*");
           }
      System.out.print("\n");
     }             
   }
}

import java.util.Scanner;
class diamondShape
{
      public static void main(String[] args)
    {
        System.out.print("Enter number of rows: ");
        Scanner in = new Scanner(System.in);
        int num=in.nextInt();
        for(int i=1;i<=num;i++)
        {
           for(int j=num;j>=i;j--)
           {
            System.out.print(" ");
           }
           for(int m=1;m<=i;m++)
           {
           System.out.print(" *");
           }
       System.out.print("\n");
       }    
       for(int i=1;i<=num;i++)
       {
           for(int j=1;j<=i;j++)
           {
           System.out.print(" ");
           }
           for(int m=num;m>=i;m--)
           {
           System.out.print(" *");
           }
        System.out.print("\n");
        }   
    }
   
}

import java.io.*;
import java.net.*;
class slidingSender
{
    public void process()
    {
        try
        {
            ServerSocket server= new ServerSocket(2500);
            Socket client = server.accept();
            BufferedReader user=new BufferedReader(new InputStreamReader(System.in));
            BufferedReader br=new BufferedReader(new InputStreamReader(client.getInputStream()));
            PrintWriter pr=new PrintWriter(client.getOutputStream(),true);
            String buf[]=new String[8];
            int index=0,sws=8,rws;
            String ch;
            do
            {
                System.out.println("Enter the number of frame send to the receiver:");
                int nf=Integer.parseInt(user.readLine());
                pr.println(nf);
                if(nf<=sws-1)
                {
                    System.out.println("Enter the "+nf+" Message send to the receiver");
                    for(int i=0;i<nf;i++)
                    {
                        buf[i]=user.readLine();
                        pr.println(buf[i]);

                    }
                   
                    sws=sws-nf;
                    int ackno=Integer.parseInt(br.readLine());
                    System.out.println("Acknowledge Received For the Frame"+ackno);
                    sws=sws+nf;

                }
                else
                {
                    System.out.println("SENDER WINDOW SIZE EXCEEDS");
                }
                System.out.println("Do You Want To Continue(y/n)");
                ch=user.readLine();
                pr.println(ch);
            }
            while(ch.equals("y"));
        }
        catch(Exception e){}
    }
    public static void main(String arg[])
    {
        slidingSender s= new slidingSender();
        s.process();
    }

}

import java.io.*;
import java.net.*;

class slidingReceiver
{
    public void process()
    {
        try
        {
            Socket client = new Socket(InetAddress.getLocalHost(),2500);
            BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));
            BufferedReader user=new BufferedReader(new InputStreamReader(System.in));
            PrintWriter pr=new PrintWriter(client.getOutputStream(),true);
            int index=0,rws=8;
            String buf[]=new String[8];
            String ch;
            while(true)
            {
                do
                {
                    int nf=Integer.parseInt(br.readLine());
                    if(nf<rws-1)
                    {
                        for(int i=0;i<nf;i++)
                        {
                            buf[index]=br.readLine();
                            System.out.println(index);
                            System.out.println(buf[index]);
                            index=(index +1)%rws;
                            System.out.println(index);
                        }
                        rws = rws - nf;                      
                        System.out.println("Acknowledge Sent To Sender");
                        pr.println(index);
                        rws=rws+nf;
                    }
                    else
                    {
                        break;
                    }
                    ch=br.readLine();
                }
                while(ch.equals("y"));
            }
        }
        catch(Exception e){}
    }
    public static void main(String arg[])
    {
        slidingReceiver r= new slidingReceiver();
        r.process();
    }
}

Enter the number of frame send to the receiver:
3
Enter the 3 Message send to the receiver
hi
good
evening
Acknowledge Received For the Frame3
Do You Want To Continue(y/n)
n

0 

hi 

1 

1 

good 

2 

2 

evening 

3 

Acknowledge Sent To Sender 

import java.net.*;
import java.io.*;

class MulticastSender implements Runnable
{
    static int port;
    static MulticastSocket ms;
    static String group;
    static int status = 0 ;
    MulticastSender() throws Exception
    {
        port = 5000;
        group = "225.4.5.6";
        ms = new MulticastSocket(4000);
    }
    public void run()
    {
        while(true)
        {
            try
            {
                BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
                byte sbuf[] = new byte[2000];
                sbuf = br.readLine().getBytes();
                DatagramPacket spack = new DatagramPacket(sbuf, sbuf.length,
                                                 InetAddress.getByName(group), port);
                ms.send(spack);                                                
               
            }catch(Exception e){ System.out.println(e);}
        }
    }
    public static void main(String args[]) throws Exception
    {
        MulticastSender sender = new MulticastSender();
        Thread t = new Thread(sender);
               
        ms.joinGroup(InetAddress.getByName(group));
        t.start();
       
        int count =0;
        byte rbuf[] = new byte[1000];
        while(true)
        {
            DatagramPacket rpack =new DatagramPacket(rbuf,rbuf.length);
            ms.receive(rpack);
            String str = new String(rpack.getData(),0,rpack.getLength());
            if(str.equalsIgnoreCase("join"))
            {
                count++;
                System.out.println("Client joined the group");
                System.out.println("\ncurrently " + count + " client/clients is/are in the group");
               
            }
            else if(str.equalsIgnoreCase("leave"))
            {
                count--;
                System.out.println("Client left the group");
                System.out.println("\ncurrently " + count + " client/clients is/are in the group");
                if(count == 0)
                {
                    ms.leaveGroup(InetAddress.getByName(group));
                    ms.close();
                    break;
                }
            }
        }
    }
}

import java.io.*;
import java.net.*;
class MulticastReceiver implements Runnable
{
    static MulticastSocket ms;
    static int port;
    static int status = 0;
    MulticastReceiver() throws Exception
    {
        port = 5000;
        ms= new MulticastSocket(port);
    }
    public void run()
    {
        while(true)
        {
            try
            {
                byte rbuf[] = new byte[2000];
                DatagramPacket  rpack = new DatagramPacket(rbuf,rbuf.length);
                if (status == 1)
                {
                    ms.close();
                    break;
                }
                ms.receive(rpack);
                System.out.println(new String(rpack.getData(),0,rpack.getLength()));
            }catch(Exception e){System.out.println(e);}
        }
    }
   
    public static void main(String args[]) throws Exception
    {
        MulticastReceiver mr =new MulticastReceiver();
        Thread t = new Thread(mr);
       
        String group = "225.4.5.6";
      
        System.out.println("Do you wish to join the group?");
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        if(br.readLine().equalsIgnoreCase("yes"))
        {
            ms.joinGroup(InetAddress.getByName(group));
           
            byte sbuf[] = new byte[2000];
            sbuf = "join".getBytes();
            DatagramPacket spack = new DatagramPacket(sbuf, sbuf.length,InetAddress.getByName("localhost"),4000);
            ms.send(spack);
          
            System.out.println("Joined the group");
            t.start();
            while(true)
            {
                if(br.readLine().equalsIgnoreCase("leave"))
                {
                    status = 1;
                    byte sbuf2[] = new byte[2000];
                    sbuf2 = "leave".getBytes();
                    DatagramPacket spack2 = new DatagramPacket(sbuf2,sbuf2.length,InetAddress.getByName("localhost"),4000);
                    ms.send(spack2);
                    ms.leaveGroup(InetAddress.getByName(group));
                    break;
                }
            }
        }
    }
}

Do you wish to join the group?
yes
Joined the group
hi

Client joined the group

currently 1 client/clients is/are in the group
hi

import java.io.*;
class ShortPath
{
     public int vertex;
    public int edge;
    public int arrval[][]=new int[10][10];
    public int neigh[]=new int[10];
    public int nonnei[]=new int[10];
    public int tempnei,ntnei;
    public void getdata() throws Exception
    {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
    System.out.println("ENTER NO OF VERTEX==>");
    vertex=Integer.parseInt(br.readLine());   
    System.out.println("ENTER NO OF EDGE==>");
    edge=Integer.parseInt(br.readLine());
    for(int i=0;i<vertex;i++)
    {
        for(int j=0;j<vertex;j++)
        {
            if(i==j)
                arrval[i][j]=0;
            else
                arrval[i][j]=999;
        }
    }
    for(int k=0;k<edge;k++)
    {
        System.out.println("ENTER THE EDGE V1-V2");
        int v1=Integer.parseInt(br.readLine());
        int v2=Integer.parseInt(br.readLine());
        System.out.println("ENTER THE EDGE COST==>");
        int cost=Integer.parseInt(br.readLine());
        arrval[v1][v2]=cost;
        arrval[v2][v1]=cost;
    }
    }

      public void process()throws Exception
    {
        int i,j,k;
        for(i=0;i<vertex;i++)
    {
        tempnei=0;
        ntnei=0;
        for(j=0;j<vertex;j++)
        {
            if(arrval[i][j]!=0 && arrval[i][j]!=999)
                tempnei++;
            else
                ntnei++;
        }
        neigh[i]=tempnei;
        nonnei[i]=ntnei;
    }
    for(k=0;k<vertex;k++)
    {
        System.out.println("THE NUMBER OF NEIGHBOUR VERTEX==>"+neigh[k]);
            System.out.println("THE NUMBER OF NON-NEIGHBOUR VERTEX==>"+nonnei[k]);
    }
    for(k=0;k<vertex;k++)
    {
        for(i=0;i<vertex;i++)
        {
            for(j=0;j<vertex;j++)
            {
             arrval[i][j]=min(arrval[i][j],arrval[i][k]+arrval[k][j]);
            }
        }
}
    }
    public void display()throws Exception
    {
    System.out.println("SHORTEST PATH");
    System.out.println();
    for(int i=0;i<vertex;i++)
    {
            for(int j=0;j<vertex;j++)
            {
                System.out.print(arrval[i][j]+"\t");
            }
            System.out.println();
        }
    }

    public int min(int a,int b)
    {
        int c=a<b?a:b;
        return c;
    }

    public static void main(String arg[])throws Exception
    {
        ShortPath s=new ShortPath();
        s.getdata();
        s.display();
        s.process();
        s.display();
    }
}   

ENTER NO OF VERTEX==> 

2 

ENTER NO OF EDGE==> 

2 

ENTER THE EDGE V1-V2 

2 

3 

ENTER THE EDGE COST==> 

5 

ENTER THE EDGE V1-V2 

2 

3 

ENTER THE EDGE COST==> 

6 

SHORTEST PATH

0    999     

999    0     

THE NUMBER OF NEIGHBOUR VERTEX==>0 

THE NUMBER OF NON-NEIGHBOUR VERTEX==>2 

THE NUMBER OF NEIGHBOUR VERTEX==>0 

THE NUMBER OF NON-NEIGHBOUR VERTEX==>2 

SHORTEST PATH

0    999     

999    0  

Client Side Program

import java.io.*;
import java.net.*;
class TCPClient {

  public static void main(String args[]) throws Exception
  {
       String sentence;
       String modifiedSentence;
        BufferedReader inFromUser =
         new BufferedReader(new InputStreamReader(System.in));

      Socket clientSocket = new Socket("127.0.0.1", 6324);

        DataOutputStream outToServer =
          new DataOutputStream(clientSocket.getOutputStream());
   
       BufferedReader inFromServer =
          new BufferedReader(new
            InputStreamReader(clientSocket.getInputStream()));

        sentence = inFromUser.readLine();
        outToServer.writeBytes(sentence + '\n');

        modifiedSentence = inFromServer.readLine();

        System.out.println("FROM SERVER: " + modifiedSentence);

        clientSocket.close();
                 
    }
}

import java.io.*;
import java.net.*;

class TCPServer {

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

      ServerSocket welcomeSocket = new ServerSocket(6324);
 
      while(true) {
 
            Socket connectionSocket = welcomeSocket.accept();

           BufferedReader inFromClient =
              new BufferedReader(new
              InputStreamReader(connectionSocket.getInputStream()));

          
DataOutputStream  outToClient =
             new DataOutputStream(connectionSocket.getOutputStream());

           clientSentence = inFromClient.readLine();
           System.out.println("FROM client:" + clientSentence); 
           capitalizedSentence = clientSentence.toUpperCase() + '\n';
           outToClient.writeBytes(capitalizedSentence);
        }
    }
}

hi

FROM SERVER: HI

FROM client:hi

hi da

import java.io.*; 

import java.net.*; 

class ChatClient extends Thread 

{ 

    Socket s; 

    static PrintWriter out; 

    static BufferedReader read,in; 

    Thread t;

    ChatClient() throws Exception 

    { 

        s = new Socket("127.0.0.1",5000); 

        System.out.println("client connected to server");  

        read = new BufferedReader(new InputStreamReader(System.in)); 

        in=new BufferedReader(new InputStreamReader(s.getInputStream())); 

        out=new PrintWriter(s.getOutputStream()); 

        t=new Thread(this); 

        t.start(); 

    } 

     

    public void run() 

    { 

        String str1; 

        while(true) 

        { 

            try 

            { 

                      str1=in.readLine(); 

                      System.out.println("\n"+"From server: "+str1); 

                } 

                catch(Exception e) 

                { 

                       System.out.println(e); 

            } 

        } 

    }

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

    { 

        String str2; 

        new ChatClient(); 

        while(true) 

        { 

            str2=read.readLine(); 

            out.println(str2); 

            out.flush();   

           } 

    } 

}

import java.io.*;
import java.net.*;

class ChatServerTCP extends Thread
{
    ServerSocket server;
    Socket s;
    static PrintWriter out;
    static BufferedReader read,in;
    Thread t;

ChatServerTCP() throws Exception
{
    server = new ServerSocket(5000);
    System.out.println("Server is waiting for client");
    s=server.accept();
    System.out.println("connection is established "+s.getInetAddress());
    read = new BufferedReader(new InputStreamReader(System.in));
    in=new BufferedReader(new InputStreamReader(s.getInputStream()));
    out=new PrintWriter(s.getOutputStream());
    t=new Thread(this);
    t.start();
}

public void run()
{
    String str1;
    while(true)
    {
        try
            {
                  str1=in.readLine();
                  System.out.println("\n"+"From client: "+str1);
            }
            catch(Exception e)
            {
                   System.out.println(e);
            }
      }
}

public static void main(String args[]) throws Exception
{
    ChatServerTCP cs = new ChatServerTCP();
    String str2;
    while(true)
    {
             str2=read.readLine();
             out.println(str2);
             out.flush(); 
       }
}
}

client connected to server
hi

From server: hi da

how r u?

From server: fine

Server is waiting for client 

connection is established /127.0.0.1 

From client: hi 

hi da

From client:

From client: how r u? 

fine

import java.util.Scanner;

class solutions 

{

         public static void main(String[] args) 

        { 

                int a,b,c; 

                double x,y; 

                Scanner s=new Scanner(System.in); 

                System.out.println("Enter the values of a, b, c:");                        

                a=s.nextInt(); 

                b=s.nextInt(); 

                c=s.nextInt(); 

                int k=(b*b)-4*a*c; 

                if(k<0) 

                { 

                        System.out.println("No real roots");                                

                } 

                else 

                { 

                        double l=Math.sqrt(k); 

                        x=(-b-l)/2*a; 

                        y=(-b+l)/2*a; 

                        System.out.println("Roots of given equation:"+x+" 

"+y);                                

                } 

        } 

}

Enter the values of a, b, c:
5
5
2
No real roots

import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
public class TransparencyDemo extends JPanel 

{
    public static void main(String[] args) 

    {
        JFrame window = new JFrame("TransparencyDemo");
        TransparencyDemo content = new TransparencyDemo();
        window.setContentPane(content);
        window.pack(); 
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        window.setLocation( (screenSize.width - window.getWidth())/2,
                (screenSize.height - window.getHeight())/2 );
        window.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        window.setVisible(true);
    }
    private JSlider triangleTransparency;
    private JSlider ovalTransparency;
    private JSlider rectangleTransparency;
    private JSlider textTransparency;

    private Font textFont = new Font("Serif",Font.BOLD,42);

    private JPanel display = new JPanel() {
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            Color triangleColor = new Color(255,0,0,triangleTransparency.getValue());
            Color ovalColor = new Color(0,255,0,ovalTransparency.getValue());
            Color rectangleColor = new Color(0,0,255,rectangleTransparency.getValue());
            Color textColor = new Color(0,0,0,textTransparency.getValue());
            g.setColor(triangleColor);
            g.fillPolygon(new int[] { scaleX(0.25), scaleX(0.7), scaleX(0.1) },
                    new int[] { scaleY(0.1), scaleY(0.7), scaleY(0.7) },
                    3);
            g.setColor(ovalColor);
            g.fillOval(scaleX(0.3),scaleY(0.45),getWidth()/2,getHeight()/2);
            g.setColor(rectangleColor);
            g.fillRect(scaleX(0.4),scaleY(0.15),getWidth()/2,getHeight()/2);
            FontMetrics metrics = g.getFontMetrics(textFont);
            int lineWidth1 = metrics.stringWidth("Transparency");
            int lineWidth2 = metrics.stringWidth("Demo");
            int textHeight = metrics.getHeight() + metrics.getAscent();
            int topSkip = (getHeight() - textHeight) / 2;
            int leftSkip1 = (getWidth() - lineWidth1) / 2;
            int leftSkip2 = (getWidth() - lineWidth2) / 2;
            g.setColor(textColor);
            g.setFont(textFont);
            g.drawString("Transparency", leftSkip1, topSkip + metrics.getAscent());
            g.drawString("Demo", leftSkip2, topSkip + metrics.getAscent() + metrics.getHeight());
        }
        private int scaleX(double x) {
            return (int)(x * getWidth());
        }
        private int scaleY(double y) {
            return (int)(y * getHeight());
        }
    };
   
    private ChangeListener listener = new ChangeListener() {
        public void stateChanged(ChangeEvent arg0) {
            display.repaint();
        }
    };

    public TransparencyDemo() {
        setLayout(new BorderLayout(3,3));
        setBorder(BorderFactory.createLineBorder(Color.GRAY,2));
        setBackground(Color.GRAY);
        display.setBackground(Color.WHITE);
        display.setPreferredSize(new Dimension(400,300));
        add(display,BorderLayout.CENTER);
        JPanel bottom = new JPanel();
        bottom.setLayout(new GridLayout(4,2,3,3));
        add(bottom,BorderLayout.SOUTH);
        bottom.add( new JLabel("  Triangle Transparency:") );
        triangleTransparency = new JSlider(0,255);
        triangleTransparency.addChangeListener(listener);
        bottom.add( triangleTransparency );
        bottom.add( new JLabel("  Oval Transparency:") );
        ovalTransparency = new JSlider(0,255);
        ovalTransparency.addChangeListener(listener);
        bottom.add( ovalTransparency );
        bottom.add( new JLabel("  Rectangle Transparency:") );
        rectangleTransparency = new JSlider(0,255);
        rectangleTransparency.addChangeListener(listener);
        bottom.add( rectangleTransparency );
        bottom.add( new JLabel("  Text Transparency:") );
        textTransparency = new JSlider(0,255);
        textTransparency.addChangeListener(listener);
        bottom.add( textTransparency );
    }
}

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class ToolBarDemo extends JPanel 

{  
    public static void main(String[] args) 

    {
        JFrame window = new JFrame("ToolBarDemo");
        ToolBarDemo content = new ToolBarDemo();
        window.setContentPane(content);
        window.pack(); 
        window.setResizable(false);
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        window.setLocation( (screenSize.width - window.getWidth())/2,
                (screenSize.height - window.getHeight())/2 );
        window.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        window.setVisible(true);
    }
    private class Display extends JPanel implements MouseListener, MouseMotionListener 

    {
        private BufferedImage OSC;  // Off-screen canvas.
        private Color currentColor = Color.RED;  // Current drawing color.
        private int prevX, prevY;  // Previous mouse position, during mouse drags.
        private BasicStroke stroke;  // Stroke used for drawing.
        Display() { // constructor.
            addMouseListener(this);
            addMouseMotionListener(this);
            setPreferredSize(new Dimension(300,300));
            stroke = new BasicStroke(3,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
        }
        void setCurrentColor(Color c) {  // change current drawing color
            currentColor = c;
        }

        void clear() { // clear the drawing area by filling it with white
            if (OSC != null) {
                Graphics g = OSC.getGraphics();
                g.setColor(Color.WHITE);
                g.fillRect(0,0,getWidth(),getHeight());
                g.dispose();
                repaint();
            }
        }
        public void paintComponent(Graphics g) { // just copies OSC to screen
            checkImage();
            g.drawImage(OSC,0,0,null);
        }
        void checkImage() {  // create or resize OSC if necessary
            if (OSC == null) {
                // Create the OSC, with a size to match the size of the panel.
                OSC = new BufferedImage(getWidth(),getHeight(),BufferedImage.TYPE_INT_RGB);
                clear();
            }
            else if (OSC.getWidth() != getWidth() || OSC.getHeight() != getHeight()) {
                BufferedImage newOSC;
                newOSC = new BufferedImage(getWidth(),getHeight(),BufferedImage.TYPE_INT_RGB);
                Graphics g = newOSC.getGraphics();
                g.drawImage(OSC,0,0,getWidth(),getHeight(),null);
                g.dispose();
                OSC = newOSC;
            }
        }
        public void mousePressed(MouseEvent e) {
            prevX = e.getX();
            prevY = e.getY();
        }
        public void mouseDragged(MouseEvent e) {
            Graphics2D g2 = (Graphics2D)OSC.getGraphics();
            g2.setColor(currentColor);
            g2.setStroke(stroke);
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2.drawLine(prevX,prevY,e.getX(),e.getY());
            g2.dispose();
            repaint();
            prevX = e.getX();
            prevY = e.getY();
        }
        public void mouseReleased(MouseEvent e) { }
        public void mouseMoved(MouseEvent e) { }
        public void mouseClicked(MouseEvent e) { }
        public void mouseEntered(MouseEvent e) { }
        public void mouseExited(MouseEvent e) { }
    }


    private Display display; 

    public ToolBarDemo() {
        setLayout(new BorderLayout(2,2));
        setBackground(Color.GRAY);
        setBorder(BorderFactory.createLineBorder(Color.GRAY,2));
        display = new Display();
        add(display, BorderLayout.CENTER);
        JToolBar toolbar = new JToolBar();
        add(toolbar, BorderLayout.NORTH);
        ButtonGroup group = new ButtonGroup();
        toolbar.add( makeColorRadioButton(Color.RED,group,true) );
        toolbar.add( makeColorRadioButton(Color.GREEN,group,false) );
        toolbar.add( makeColorRadioButton(Color.BLUE,group,false) );
        toolbar.addSeparator(new Dimension(20,20));
        toolbar.add( makeClearButton() );
    }
   
    private JRadioButton makeColorRadioButton(final Color c, ButtonGroup grp, boolean selected) {       
        BufferedImage image = new BufferedImage(30,30,BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();
        g.setColor(Color.LIGHT_GRAY);
        g.fillRect(0,0,30,30);
        g.setColor(c);
        g.fill3DRect(1, 1, 24, 24, true);
        g.dispose();
        Icon unselectedIcon = new ImageIcon(image);
        /* Create an ImageIcon for the selected state of the button. */
        image = new BufferedImage(30,30,BufferedImage.TYPE_INT_RGB);
        g = image.getGraphics();
        g.setColor(Color.DARK_GRAY);
        g.fillRect(0,0,30,30);
        g.setColor(c);
        g.fill3DRect(3, 3, 24, 24, false);
        g.dispose();
        Icon selectedIcon = new ImageIcon(image);
       /* Create and configure the button. */
        JRadioButton button = new JRadioButton(unselectedIcon);
        button.setSelectedIcon(selectedIcon);
        button.addActionListener( new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // The action for this button sets the current drawing color
                // in the display to c.
                display.setCurrentColor(c);
            }
        });
        grp.add(button);
        if (selected)
            button.setSelected(true);
        return button;
    } // end makeColorRadioButton   
    private JButton makeClearButton() {
        BufferedImage image = new BufferedImage(24,24,BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = (Graphics2D)image.getGraphics();
        g2.setColor(Color.LIGHT_GRAY);
        g2.fillRect(0,0,24,24);
        g2.setStroke( new BasicStroke(3));
        g2.setColor(Color.BLACK);
        g2.drawLine(4,4,20,20);
        g2.drawLine(4,20,20,4);
        g2.dispose();
        Icon clearIcon = new ImageIcon(image);
        Action clearAction = new AbstractAction(null,clearIcon) {
            public void actionPerformed(ActionEvent evt) {
                display.clear();
            }
        };
        clearAction.putValue(Action.SHORT_DESCRIPTION, "Clear the Display");
        JButton button = new JButton(clearAction);
        return button;
    }
}