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Monday, 11 November 2013

Linux Terminal Commands

Install Command

sudo apt-get install <package-name>
Example:
Installing vlc media player

sudo apt-get install vlc



ls Command

ls -l
list folders and files with read write permissions and user groups

ls -aThis command shows hidden files and folders

ls -al
ls -la


Clear Command

clear

this command clears the screen

Manual Command

man <command>

this command shows manual of the commands

example man ls shows manual command of ls


q to quit the manual screen back to terminal commands

ifconfig command

ifconfig command ip network address details

netstat command

netstat command used to show network status like ip addresses of local and foreign; port, pid, network protocols

cat Command 

cat command concatenate files and print on the standard output.























Java Program: Down casting Inheritence

Program

public class downcasting {
   public static void main(String[] args)
    {
     fordd f;
     benzz b;
     BMWw bm;
     carr c,cc,ccc;
     c=new fordd();
     cc=new benzz();
     ccc=new BMWw();
     f=(fordd)c; // downcasting or narrowing or specialization
     b=(benzz)cc;
     bm=(BMWw)ccc;
     f.car();
     b.car();
     bm.car();
    }
}
class carr
{
    void car()
    {
        System.out.println("This super class car method");
    }
}
class fordd extends carr
{
    void car()
    {
        System.out.println("This sub class Ford car method");
    }
}
class benzz extends carr
{
     void car()
    {
        System.out.println("This sub class Benz car method");
    }
}
class BMWw extends carr
{
     void car()
    {
        System.out.println("This sub class BMW car method");
    }

}

Output



Java Program: Up casting Program in inheritance

Program

public class upcasting {
   public static void main(String[] args)
    {
     car c,cc,ccc,o;
     o=new car();
     o.car(); //no casting
     c=(car)new ford(); //upcasting ford sub class to super class
     c.car();
     cc=(car)new benz();//upcasting ford sub class to super class
     cc.car();
     ccc=(car)new BMW();//upcasting ford sub class to super class      
     ccc.car();
   
    }
}
class car
{
    void car()
    {
        System.out.println("This super class car method");
    }
}
class ford extends car
{
    @Override
    void car()
    {
        System.out.println("This sub class Ford car method");
    }
}
class benz extends car
{
     @Override
    void car()
    {
        System.out.println("This sub class Benz car method");
    }
}
class BMW extends car
{
     @Override
    void car()
    {
        System.out.println("This sub class BMW car method");
    }

}

Output



Java Program: Inheritance Super Keyword

Program

class inheritance
{
 public static void main(String[] args)
 {
  apple a=new apple();
  a.disp();
 }
}
class fruit
{
 String f="fruit";
 public void disp()
 {
  System.out.println("Base Class "+f);
 }
}
class apple extends fruit
{
 String f="Apple";
 public void disp()
 {
  System.out.println("Derived Class  "+f);
  super.disp();
  System.out.println("Super Class "+super.f);
 }

}

Output


Java Program: File I/O Fileoutputstream to create file

Program

import java.io.*;
public class createfile {
    public static void main(String[] args)
    {
        try
        {
        createfile();
        }
        catch(Exception ex)
        {
            System.out.println("File Exceptio occured");
        }    
    }
    public static void createfile() throws java.io.IOException
    {
        DataInputStream d=new DataInputStream(System.in);
        FileOutputStream f=new FileOutputStream("jack.txt",true);
        BufferedOutputStream b=new BufferedOutputStream(f,1024);
        System.out.println("Enter $ at the end to finish text");
        char c;
        while((c=(char)d.read())!='$')
        {
            b.write(c);          
        }
        b.close();
    }

}

Output



Java Program: AWT Frame Closing Event

Program

import java.awt.*;
import java.awt.event.*;
public class awtexample extends Frame{
    public static void main(String[] args)
    {
        Frame f= new Frame("New Frame");
        f.setSize(400, 500);
        f.setVisible(true);
        f.addWindowListener(new WindowAdapter(){
        public void windowClosing(WindowEvent e)
        {
        System.exit(0);
        }
     });
    }
}

Output