JAVA PROGRAMMING ASSIGNMENT 2 QUESTIONS

SIR C R REDDY COLLEGE OF ENGINEERING, ELURU

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

JAVA PROGRAMMING ASSIGNMENT 2 QUESTIONS

1. How can you perform thread scheduling by setting priorities to threads? Explain the same with an example.
2. Write a Java program to read from file and print file data on the user screen.
3. Explain various states in the life cycle of an applet. And also give the syntax of each state.
4. Explain the delegation event model of handling events with a suitable JAVA program
5. Write short notes on
• Different ways of creating a frame in AWT
• AWT Layout Manager
• JAVA AWT Checkbox 

Exercise – 16 (Swings - Continued)

Exercise – 16 (Swings - Continued)

a). Write a JAVA program that to create a single ball bouncing inside a JPanel.

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

public class BouncingBall extends JPanel {

  // Box height and width
  int width;
  int height;

  // Ball Size
  float radius = 40;
  float diameter = radius * 2;

  // Center of Call
  float X = radius + 50;
  float Y = radius + 20;

  // Direction
  float dx = 3;
  float dy = 3;

  public BouncingBall() {

    Thread thread = new Thread() {
      public void run() {
        while (true) {

          width = getWidth();
          height = getHeight();

          X = X + dx ;
          Y = Y + dy;

          if (X - radius < 0) {
            dx = -dx;
            X = radius;
          } else if (X + radius > width) {
            dx = -dx;
            X = width - radius;
          }

          if (Y - radius < 0) {
            dy = -dy;
            Y = radius;
          } else if (Y + radius > height) {
            dy = -dy;
            Y = height - radius;
          }
          repaint();

          try {
            Thread.sleep(50);
          } catch (InterruptedException ex) {
          }

        }
      }
    };
    thread.start();
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.setColor(Color.RED);
    g.fillOval((int)(X-radius), (int)(Y-radius), (int)diameter, (int)diameter);
  }

  public static void main(String[] args) {
    JFrame frame = new JFrame("Bouncing Ball");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300, 200);
    frame.setContentPane(new BouncingBall());
    frame.setVisible(true);
  }
}

b). Write a JAVA program JTree as displaying a real tree upside down

import javax.swing.*; 
import javax.swing.tree.DefaultMutableTreeNode; 
public class TreeExample extends JFrame { 
JFrame f; 
TreeExample(){ 
    f=new JFrame(); 
    DefaultMutableTreeNode style=new DefaultMutableTreeNode("Style"); 
    DefaultMutableTreeNode color=new DefaultMutableTreeNode("color"); 
    DefaultMutableTreeNode font=new DefaultMutableTreeNode("font"); 
    style.add(color); 
    style.add(font); 
    DefaultMutableTreeNode red=new DefaultMutableTreeNode("red"); 
    DefaultMutableTreeNode blue=new DefaultMutableTreeNode("blue"); 
    DefaultMutableTreeNode black=new DefaultMutableTreeNode("black"); 
    DefaultMutableTreeNode green=new DefaultMutableTreeNode("green"); 
    color.add(red); color.add(blue); color.add(black); color.add(green);     
    JTree jt=new JTree(style); 
    f.add(jt); 
    f.setSize(200,200); 
    f.setVisible(true); 
} 
public static void main(String[] args) { 
    new TreeExample(); 
}}

Exercise - 15 (Swings)

Exercise - 15 (Swings)

a).Write a java program to built a Calculator in swings

import javax.swing.*;

import java.awt.event.*;

 

 

class Calc implements ActionListener

{

    JFrame f;

    JTextField t;

    JButton b1,b2,b3,b4,b5,b6,b7,b8,b9,b0,bdiv,bmul,bsub,badd,bdec,beq,bdel,bclr;

 

    static double a=0,b=0,result=0;

    static int operator=0;

 

    Calc()

    {

        f=new JFrame("Calculator");

        t=new JTextField();

        b1=new JButton("1");

        b2=new JButton("2");

        b3=new JButton("3");

        b4=new JButton("4");

        b5=new JButton("5");

        b6=new JButton("6");

        b7=new JButton("7");

        b8=new JButton("8");

        b9=new JButton("9");

        b0=new JButton("0");

        bdiv=new JButton("/");

        bmul=new JButton("*");

        bsub=new JButton("-");

        badd=new JButton("+");

        bdec=new JButton(".");

        beq=new JButton("=");

        bdel=new JButton("Delete");

        bclr=new JButton("Clear");

        

        t.setBounds(30,40,280,30);

        b7.setBounds(40,100,50,40);

        b8.setBounds(110,100,50,40);

        b9.setBounds(180,100,50,40);

        bdiv.setBounds(250,100,50,40);

        

        b4.setBounds(40,170,50,40);

        b5.setBounds(110,170,50,40);

        b6.setBounds(180,170,50,40);

        bmul.setBounds(250,170,50,40);

        

        b1.setBounds(40,240,50,40);

        b2.setBounds(110,240,50,40);

        b3.setBounds(180,240,50,40);

        bsub.setBounds(250,240,50,40);

        

        bdec.setBounds(40,310,50,40);

        b0.setBounds(110,310,50,40);

        beq.setBounds(180,310,50,40);

        badd.setBounds(250,310,50,40);

        

        bdel.setBounds(60,380,100,40);

        bclr.setBounds(180,380,100,40);

        

        f.add(t);

        f.add(b7);

        f.add(b8);

        f.add(b9);

        f.add(bdiv);

        f.add(b4);

        f.add(b5);

        f.add(b6);

        f.add(bmul);

        f.add(b1);

        f.add(b2);

        f.add(b3);

        f.add(bsub);

        f.add(bdec);

        f.add(b0);

        f.add(beq);

        f.add(badd);

        f.add(bdel);

        f.add(bclr);

        

        f.setLayout(null);

        f.setVisible(true);

        f.setSize(350,500);

        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        f.setResizable(false);

        

        b1.addActionListener(this);

        b2.addActionListener(this);

        b3.addActionListener(this);

        b4.addActionListener(this);

        b5.addActionListener(this);

        b6.addActionListener(this);

        b7.addActionListener(this);

        b8.addActionListener(this);

        b9.addActionListener(this);

        b0.addActionListener(this);

        badd.addActionListener(this);

        bdiv.addActionListener(this);

        bmul.addActionListener(this);

        bsub.addActionListener(this);

        bdec.addActionListener(this);

        beq.addActionListener(this);

        bdel.addActionListener(this);

        bclr.addActionListener(this);

    }

 

    public void actionPerformed(ActionEvent e)

    {

        if(e.getSource()==b1)

            t.setText(t.getText().concat("1"));

        

        if(e.getSource()==b2)

            t.setText(t.getText().concat("2"));

        

        if(e.getSource()==b3)

            t.setText(t.getText().concat("3"));

        

        if(e.getSource()==b4)

            t.setText(t.getText().concat("4"));

        

        if(e.getSource()==b5)

            t.setText(t.getText().concat("5"));

        

        if(e.getSource()==b6)

            t.setText(t.getText().concat("6"));

        

        if(e.getSource()==b7)

            t.setText(t.getText().concat("7"));

        

        if(e.getSource()==b8)

            t.setText(t.getText().concat("8"));

        

        if(e.getSource()==b9)

            t.setText(t.getText().concat("9"));

        

        if(e.getSource()==b0)

            t.setText(t.getText().concat("0"));

        

        if(e.getSource()==bdec)

            t.setText(t.getText().concat("."));

        

        if(e.getSource()==badd)

        {

            a=Double.parseDouble(t.getText());

            operator=1;

            t.setText("");

        } 

        

        if(e.getSource()==bsub)

        {

            a=Double.parseDouble(t.getText());

            operator=2;

            t.setText("");

        }

        

        if(e.getSource()==bmul)

        {

            a=Double.parseDouble(t.getText());

            operator=3;

            t.setText("");

        }

        

        if(e.getSource()==bdiv)

        {

            a=Double.parseDouble(t.getText());

            operator=4;

            t.setText("");

        }

        

        if(e.getSource()==beq)

        {

            b=Double.parseDouble(t.getText());

        

            switch(operator)

            {

                case 1: result=a+b;

                    break;

        

                case 2: result=a-b;

                    break;

        

                case 3: result=a*b;

                    break;

        

                case 4: result=a/b;

                    break;

        

                default: result=0;

            }

        

            t.setText(""+result);

        }

        

        if(e.getSource()==bclr)

            t.setText("");

        

        if(e.getSource()==bdel)

        {

            String s=t.getText();

            t.setText("");

            for(int i=0;i<s.length()-1;i++)

            t.setText(t.getText()+s.charAt(i));

        }        

    }

 

    public static void main(String...s)

    {

        new Calc();

    }

}

b). Write a JAVA program to display the digital watch in swing tutorial.

import javax.swing.*; 
import java.awt.*; 
import java.text.*; 
import java.util.*; 
public class DigitalWatch implements Runnable{ 
JFrame f; 
Thread t=null; 
int hours=0, minutes=0, seconds=0; 
String timeString = ""; 
JButton b; 
 
DigitalWatch(){ 
    f=new JFrame(); 
     
    t = new Thread(this); 
        t.start(); 
     
    b=new JButton(); 
        b.setBounds(100,100,100,50); 
     
    f.add(b); 
    f.setSize(300,400); 
    f.setLayout(null); 
    f.setVisible(true); 
} 
 
 public void run() { 
      try { 
         while (true) { 
 
            Calendar cal = Calendar.getInstance(); 
            hours = cal.get( Calendar.HOUR_OF_DAY ); 
            if ( hours > 12 ) hours -= 12; 
            minutes = cal.get( Calendar.MINUTE ); 
            seconds = cal.get( Calendar.SECOND ); 
 
            SimpleDateFormat formatter = new SimpleDateFormat("hh:mm:ss"); 
            Date date = cal.getTime(); 
            timeString = formatter.format( date ); 
 
            printTime(); 
 
            t.sleep( 1000 );  // interval given in milliseconds 
         } 
      } 
      catch (Exception e) { } 
 } 
 
public void printTime(){ 
b.setText(timeString); 
} 
 
public static void main(String[] args) { 
    new DigitalWatch(); 
         
 
} 
} 

Exercise - 14 (Event Handling)

Exercise - 14 (Event Handling)

a).Write a JAVA program that display the x and y position of the cursor movement using
Mouse.

import java.awt.*;

import java.awt.event.*;

import java.applet.Applet;

public class AppletMouse extends Applet implements MouseListener, MouseMotionListener

{

  int x, y;

  String str="";

  public void init()

  {

    addMouseListener(this);

    addMouseMotionListener(this);

  }

                                    // override ML 5 abstract methods

  public void mousePressed(MouseEvent e)

  {

    x = e.getX();

    y = e.getY();

    str = "Mouse Pressed";

    repaint();

  }

  public void mouseReleased(MouseEvent e)

  {

    x = e.getX();

    y = e.getY();

    str = "Mouse Released";

    repaint();

   }

   public void mouseClicked(MouseEvent e)

   {

     x = e.getX();

     y = e.getY();

     str = "Mouse Clicked";

     repaint();

   }

   public void mouseEntered(MouseEvent e)

   {

     x = e.getX();

     y = e.getY();

     str = "Mouse Entered";

     repaint();

   }

   public void mouseExited(MouseEvent e)

   {

     x = e.getX();

     y = e.getY();

     str = "Mouse Exited";

     repaint();

   }

                                    // override two abstract methods of MouseMotionListener

   public void mouseMoved(MouseEvent e)

   {

     x = e.getX();

     y = e.getY();

     str = "Mouse Moved";

     repaint();

   }

   public void mouseDragged(MouseEvent e)

   {

     x = e.getX();

     y = e.getY();

     str = "Mouse dragged";

     repaint();

   }

                                    // called by repaint() method

   public void paint(Graphics g)

   {

     g.setFont(new Font("Monospaced", Font.BOLD, 20));

     g.fillOval(x, y, 10, 10);

     g.drawString(x + "," + y,  x+10, y -10);

     g.drawString(str, x+10, y+20);

     showStatus(str + " at " + x + "," + y);

   }

}

Applet code:Applet code save as .html  file

<html>  

<body>  

<applet code="AppletMouse.class" width="300" height="300">  

</applet>  

</body>  

</html>  

b).Write a JAVA program that identifies key-up key-down event user entering text in a  Applet.

import java.applet.Applet;

import java.awt.*;

public class KeyUpDown1 extends Applet {

   private Font f;

   private String letter;

   private boolean first;

   public void init()

   {

      f = new Font( "Courier", Font.BOLD, 72 );

      first = true;

   }

   public void paint( Graphics g )

   {

      g.setFont( f );

      if ( !first )

         g.drawString( letter, 75, 70 );

   }

   public boolean keyDown( Event e, int key )

   {

      showStatus( "keyDown: the " + ( char ) key +

                  " was pressed." );

      letter = String.valueOf( ( char ) key );

      first = false;

      repaint();

      return true;   // event has been handled

   }

   public boolean keyUp( Event e, int key )

   {

      showStatus( "keyUp: the " + ( char ) key +

                  " was released." );

      return true;   // event has been handled

   }

}

Applet code:Applet code save as .html

<html>  

<body>  

<applet code="KeyUpDown1.class" width="300" height="300">  

</applet>  

</body>  

</html>  

Exercise - 13 (Applet)

Exercise - 13 (Applet)

a).Write a JAVA program to paint like paint brush in applet.

import java.awt.*;  

import java.awt.event.*;  

import java.applet.*;  

public class MouseDrag extends Applet implements MouseMotionListener

{

public void init()

{  

addMouseMotionListener(this);  

setBackground(Color.red);  

}  

public void mouseDragged(MouseEvent me)

{  

Graphics g=getGraphics();  

g.setColor(Color.white);  

g.fillOval(me.getX(),me.getY(),10,10);  // (x-position, y-postion, width, height)

}  

public void mouseMoved(MouseEvent me)

{

}  

}

Applet Code: Applet Code save as .html file.

<html>

<applet code="MouseDrag.class" height=300 width=400>

</applet>

</html>

b) Write a JAVA program to display analog clock using Applet.

import java.applet.*;  

import java.awt.*;  

import java.util.*;  

import java.text.*;  

public class MyClock extends Applet implements Runnable 

{  

int width, height;  

Thread t = null;  

boolean threadSuspended;  

int hours=0, minutes=0, seconds=0;  

String timeString = "";  

public void init() 

{  

      width = getSize().width;  

      height = getSize().height;  

setBackground( Color.black );  

    }  

public void start() 

{  

if ( t == null ) 

{  

t = new Thread( this );  

t.setPriority( Thread.MIN_PRIORITY );  

threadSuspended = false;  

t.start();  

}  

else 

{  

if ( threadSuspended ) 

{  

threadSuspended = false;  

synchronized( this ) 

{  

notify();  

            }  

          }  

      }  

    }  

    public void stop() 

{  

      threadSuspended = true;  

    }  

public void run() 

{  

      try 

{  

          while (true) 

{  

            Calendar cal = Calendar.getInstance();  

            hours = cal.get( Calendar.HOUR_OF_DAY );  

            if ( hours> 12 ) hours -= 12;  

            minutes = cal.get( Calendar.MINUTE );  

            seconds = cal.get( Calendar.SECOND );  

            SimpleDateFormat formatter = new SimpleDateFormat( "hh:mm:ss", Locale.getDefault() );  

            Date date = cal.getTime();  

            timeString = formatter.format( date );  

            // Now the thread checks to see if it should suspend itself  

            if ( threadSuspended ) 

{  

synchronized( this ) 

{  

                  while ( threadSuspended ) 

{  

wait();  

                  }  

                }  

            }  

repaint();  

t.sleep( 1000 );  // interval specified in milliseconds  

          }  

      }  

      catch (Exception e) 

{ 

}

    }  

    void drawHand( double angle, int radius, Graphics g ) 

{  

      angle -= 0.5 * Math.PI;  

      int x = (int)( radius*Math.cos(angle) );  

      int y = (int)( radius*Math.sin(angle) );  

g.drawLine( width/2, height/2, width/2 + x, height/2 + y );  

    }  

    void drawWedge( double angle, int radius, Graphics g ) 

{  

      angle -= 0.5 * Math.PI;  

      int x = (int)( radius*Math.cos(angle) );  

      int y = (int)( radius*Math.sin(angle) );  

      angle += 2*Math.PI/3;  

      int x2 = (int)( 5*Math.cos(angle) );  

      int y2 = (int)( 5*Math.sin(angle) );  

      angle += 2*Math.PI/3;  

      int x3 = (int)( 5*Math.cos(angle) );  

      int y3 = (int)( 5*Math.sin(angle) );  

g.drawLine( width/2+x2, height/2+y2, width/2 + x, height/2 + y );  

g.drawLine( width/2+x3, height/2+y3, width/2 + x, height/2 + y );  

g.drawLine( width/2+x2, height/2+y2, width/2 + x3, height/2 + y3 );  

    }  

    public void paint( Graphics g ) 

{  

g.setColor( Color.white );  

drawWedge( 2*Math.PI * hours / 12, width/5, g );  

drawWedge( 2*Math.PI * minutes / 60, width/3, g );  

drawHand( 2*Math.PI * seconds / 60, width/2, g );  

g.setColor( Color.white );  

g.drawString( timeString, 10, height-10 );  

    }  

}

Applet Code: Applet Code save as .html file.

<html>

<applet code="MyClock.class" height=300 width=400>

</applet>

</html>

c). Write a JAVA program to create different shapes and fill colors using Applet.

import java.applet.*;

import java.awt.*;

public class  ShapeColor extends Applet

{

  int x=300,y=100,r=50;

public void paint(Graphics g)

{

g.setColor(Color.red);  //Drawing line color is red

g.drawLine(3,300,200,10);

g.setColor(Color.magenta);  

g.drawString("Line",100,100);

g.drawOval(x-r,y-r,100,100);

g.setColor(Color.yellow);  //Fill the yellow color in circle

g.fillOval( x-r,y-r, 100, 100 );

g.setColor(Color.magenta);

g.drawString("Circle",275,100);

g.drawRect(400,50,200,100);

g.setColor(Color.yellow);  //Fill the yellow color in rectangel

g.fillRect( 400, 50, 200, 100 );

g.setColor(Color.magenta);

g.drawString("Rectangel",450,100);

  }

}

Applet Code: Applet Code save as .html file.

<html>

<applet code="ShapeColor.class" height=300 width=400>

</applet>

</html>

Exercise – 12 (Packages)

Exercise – 12 (Packages) 

a). Write a JAVA program illustrate class path 

import java.net.URL;

import java.net.URLClassLoader;
public class App
{
public static void main(String[] args)
{
ClassLoader sysClassLoader = ClassLoader.getSystemClassLoader();
URL[] urls = ((URLClassLoader)sysClassLoader).getURLs();
for(int i=0; i< urls.length; i++)
{
System.out.println(urls[i].getFile());
}
}
}

b). Write a case study on including in class path in your os environment of your package.  

COPEING THE PATH OF JAVA:-

First of all go to MYCOMPUTER and go to the drive where the java is installed.In that go to

PROGRAM FILES and then double click on java folder.

In that we have observed there is a folder with name java jdk,double click on the java jdk folder

and then go into the bin folder.

At this time we have to copy the path of the bin folder.

SETTING THE JAVA PATH:-

Inorder to set the path of the java in our system,first of all we need to open CONTROL PANEL

in our system and go to SYSTEM SETTINGS .

In system settings we need to go into the ADVANCED SYSTEM SETTINGS settings.In

advanced system settings we just click on ENVIRONMENT VARIABLES option.

In USER VARIABLES click on NEW button and type the " path" at VARIABLE NAME.

We need to paste the previously copied path of the bin folder at the place of VARIABLE VALUE.

Finally click on OK and then OK,then close the MYCOMPUTR window.Now the java path is set.We are ready to use java facilities in our computer.

c). Write a JAVA program that import and use the defined your package in the previous  Problem

1).

package pack;

public class Addition

{

private double d1,d2;

public Addition(double a, double b)

{

d1=a;

d2=b;

}

public void sum()

{

System.out.println("Sum inside of  class Addition is:"+(d1+d2));

}

}

Compilation of the program :- javac -d . Addition.java

2).

import pack.Addition;

class Use

{

public static void main(String args[])

{

Addition obj=new Addition(10,15.5);

obj.sum();

}

}

Exercise - 11 (Threads continuity)

Exercise - 11 (Threads continuity)

a).Write a JAVA program Producer Consumer Problem

import java.util.LinkedList; 
public class Threadexample 
{ 
public static void main(String[] args) throws InterruptedException 
{ 
final PC pc = new PC(); 
Thread t1 = new Thread(new Runnable() 
{ 
@Override
public void run() 
{ 
try
{ 
pc.produce(); 
} 
catch(InterruptedException e) 
{ 
e.printStackTrace(); 
} 
} 
}); 
Thread t2 = new Thread(new Runnable() 
{ 
@Override
public void run() 
{ 
try
{ 
pc.consume(); 
} 
catch(InterruptedException e) 
{ 
e.printStackTrace(); 
} 
} 
}); 
t1.start(); 
t2.start(); 
t1.join(); 
t2.join(); 
} 
public static class PC 
{ 
LinkedList<Integer> list = new LinkedList<>(); 
int capacity = 4; 
public void produce() throws InterruptedException 
{ 
int value = 0; 
while (true) 
{ 
synchronized (this) 
{ 
while (list.size()==capacity) 
wait(); 
System.out.println("Producer produced-"+ value); 
list.add(value++); 
notify(); 
Thread.sleep(1000); 
} 
} 
} 
public void consume() throws InterruptedException 
{ 
while (true) 
{ 
synchronized (this) 
{ 
while (list.size()==0) 
wait(); 
int val = list.removeFirst(); 
System.out.println("Consumer consumed-"+ val); 
notify(); 
Thread.sleep(1000); 
} 
} 
} 
} 

}

b).Write a case study on thread Synchronization after solving the above producer consumer

problem

In computing, the producer-consumer problem (also known as the bounded-buffer problem) is a classic example of a multi-process synchronization problem. The problem describes two processes, the producer and the consumer, which share a common, fixed-size buffer used as a queue.

• The producer’s job is to generate data, put it into the buffer, and start again.
• At the same time, the consumer is consuming the data (i.e. removing it from the buffer), one piece at a time.

Problem
To make sure that the producer won’t try to add data into the buffer if it’s full and that the consumer won’t try to remove data from an empty buffer.

Solution
The producer is to either go to sleep or discard data if the buffer is full. The next time the consumer removes an item from the buffer, it notifies the producer, who starts to fill the buffer again. In the same way, the consumer can go to sleep if it finds the buffer to be empty. The next time the producer puts data into the buffer, it wakes up the sleeping consumer.

Implementation of Producer Consumer Class

• A LinkedList list – to store list of jobs in queue.
• A Variable Capacity – to check for if the list is full or not
• A mechanism to control the insertion and extraction from this list so that we do not insert into list if it is full or remove from it if it is empty.

In PC class (A class that has both produce and consume methods), a linked list of jobs and a capacity of the list is added to check that producer does not produce if the list is full.

In Producer class, the value is initialized as 0.Also, we have an infinite outer loop to insert values in the list. Inside this loop, we have a synchronized block so that only a producer or a consumer thread runs at a time.An inner loop is there before adding the jobs to list that checks if the job list is full, the producer thread gives up the intrinsic lock on PC and goes on the waiting state.If the list is empty, the control passes to below the loop and it adds a value in the list.

In the Consumer class, we again have an infinite loop to extract a value from the list.Inside, we also have an inner loop which checks if the list is empty.If it is empty then we make the consumer thread give up the lock on PC and passes the control to producer thread for producing more jobs. If the list is not empty, we go round the loop and removes an item from the list.

In both the methods, we use notify at the end of all statements. The reason is simple, once you have something in list, you can have the consumer thread consume it, or if you have consumed something, you can have the producer produce something. sleep() at the end of both methods just make the output of program run in step wise manner and not display everything all at once so that you can see what actually is happening in the program.