Octal to Decimal in Java

This program is written for to convert octal  number to decimal number programmatically. It is a important interview question and this program as logic to convert octal to decimal.

                                First we find the given number is octal or not. Then we will write logic for decimal number from octal. Observe below logic how to write logic to convert octal to decimal.

package com.rrv;
import java.math.*;
import java.util.Scanner;
//class for converting Octal to Decimal
class OctalToDecimal
{
 //main method
  public static void main(String[] args)
    {  
      //declare boolean type variable for to check given number is octal or not 
       boolean is_Octal=false;
       //create scanner object for taking values from user
       Scanner scanner=new Scanner(System.in);
       System.out.println("Enter Octal Number ");
       int octalNum=scanner.nextInt();
      //call isOctal() method for finding given number is octal or not
       is_Octal= isOctal(octalNum);
      //check given number is octal or not,if true call octalToDecimal() method else print message to console
       if (is_Octal==true){
         octalToDecimal(octalNum);
       }
      else
       {
         System.out.println("Entered Number is not octal number. Please enter Octal number");
       }
    }
// method for finding given number is octal or not
  public static boolean isOctal(int octalNum)
    { 
      //declare remainder variable for to store remainder value
        int remain=0;
     //if octal number is > zero then enter into while loop
        while(octalNum>0)
          {
              remain=octalNum%10;
               if(remain<8)
                {
                   octalNum=octalNum/10;
                 }
              else{
                  return false;
                }
          }
        return true;
     }
//method for convert into decimal
public static void octalToDecimal(int octalNum)
{
   int inputNumber=octalNum;
   int remain=0;
   int count=0;
   int decimal=0;
   while(inputNumber>0)
    {
       remain=inputNumber%10;
       //first find power value of 8 with count and multiply with remainder then add to decimal variable
       decimal=(int) (decimal+remain*Math.pow(8,count));
       count++;
      inputNumber=inputNumber/10;
    }
    System.out.println("The Decimal number for "+octalNum+"  octal is: "+decimal);
  }
}

OutPut:

Enter Octal Number 
173

The Decimal number for 173  octal is: 123

Enter Octal Number 
189

Entered Number is not octal number. Please enter Octal number

 
     
     
   

   

   
     

Array index start with zero Why?

Array is collection of fixed size homogeneous type of elements.In this post i will explain "Why Array index start with zero on-wards".Generally we cannot think about this question because no one ask this type of questions in interview or anywhere.But in present interview panels asking this question frequently.So we should knowing this one is important for improving knowledge on language(C,C++,JAVA,etc).Before knowing about our topic first we know " How does array store in memory?".Array store in memory based address value.And we are printing element then it use offset value of physical address for getting values.

                   When we are creating the array variable we declare and initialize size of the array. Then we take values from console or directly we can assign.

         Ex:

              int studentNos[]={10,20,60,30,40,80,90,100,50};

                 

                   The array variable is store in memory.The value of array variable is address of zero th index of array.See below diagram

From above diagram we can know how array is storing in memory.After creating array, array variable store only address of zeroth index.Based on this value it calculate addresses of remaining indexes of array.For example, we calculate zeroth index of array based on offset value.Now we discuss "Why array index start with zero?".

 address of zeroth index of array=array variable address + datatype in bytes *  index of array;

                                                 =1000+2*0

                                                 =1000+0

                                                 =1000

Now we got address of zero index then we get value of zeroth index by using &.

 value of zero index of array =&(1000)

                                           =10

Then remaining also calculated like above.

See below link also:

Floyd's Triangle


Tribonacci series

Binary pyramid program

Serialization vs Extranalization              

Serialization Vs Extranalization

Serializable is a Marker Interface,is empty interface means it doesn't contain any fields and methods.Marker interface give special ability to Java object at run time  by using Serialization,we can save or transfer state of on object by converting it into a byte Stream.If java class implements Serializable interface then JVM treats this class object as Serializable object.

Externalizable  is a Interface and it is a sub interface of Serializable interface.Externalizable gives capability to programmers to create rules and own mechanisms.It has two methods,are writeExternal() and readExternal().

Serialization Vs Externalization:

1. Serialization is used for default serialization.While Externalization is used for customized serialization process.

2. We can use readObject() and writeObject() of serialization for store object  into persistence or re-getting object from persistence.But in Externalization,we can use readExternal() and writeExternal() methods for store object  into persistence or re-getting object from persistence. 

3. In Serialization, control is under JVM,while in Externalization control in programmer hands.

4. In deserialization process no constructor called in Serialization interface and default constructor is called in externalization at time of deserialization.

Delete given character from text using javascript

a. Design a HTML page as below
b. You can take any sentence like the above diagram. Take only character from the user and remove the character from the given sentence and after clicking on “Click” button, display the sentence again after removing the character as below.
c. Validate for only characters.
d. Design a good looking HTML page.



<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<script>
function clickCha(){
var inn=document.getElementById('1').innerHTML;

while(inn.search(document.getElementById('cha').value)!=-1){
inn=inn.replace(document.getElementById('cha').value,"");

}
var content=document.getElementById('tab').innerHTML;
content=content+inn;
document.getElementById('tab').innerHTML=content;
return true;

}
</script>
<body><center>
<form><fieldset style='border:solid;' id='tab'>
<p id='1'>We at Nacre have created an idea work environment wherenin every Nacrean adheres to set of rules and regulations practiced in the corporate world.This exposes team to corporate culture,leading to inculcation of professionalisam,integrity,time manangement,efficient delegation of work and optimal working strategies both individually and within teams.Nacreans adhere to the following rules and regulations.</p>

Enter a Character:
<input type='text' name='tex' id='cha' value=''>
<input type='button' id='cli' value='click'
onclick='return clickCha()'><br>
</fieldset>
</form></center>
</body>
</html>