Thursday, 18 October 2012

why java is more secure

Java's security model is focused on protecting users from programs downloaded from sources across a network. Java programs run in Java Runtime Environment. Java Programs can't take any action outside those boundaries. For example, Programms are prohibited from many activities, including: 

* Reading or writing to the local disk 
* Making a network connection to any host, except the host from which the applet came 
* Creating a new process 
* Loading a new dynamic library and directly calling a native method 

Wednesday, 17 October 2012

Delete vs Truncate in SQL

TRUNCATE is a DDL commandDELETE is a DML command
TRUNCATE TABLE always locks the table and page but not each rowDELETE statement is executed using a row lock,                                             each row in the table is locked for deletion
Cannot use Where ConditionWe can specify filters in where clause
It Removes all the dataIt deletes specified data if where condition exists.
TRUNCATE TABLE cannot activate a trigger because the operation does not log individual row deletions.Delete activates a trigger because the operation                                are logged individually.
Faster in performance wise, because it is minimally logged in transaction log.Slower than truncate because, it maintain logs for every record
 Drop all object’s statistics and marks like High Water Mark free extents and leave the object really empty with the first extent. zero pages are left in the tablekeeps object’s statistics and all allocated space. After a                       DELETE statement is executed,the table can still contain empty pages.
TRUNCATE TABLE removes the data by deallocating the data pages used to store the table data and records only the page deallocations in the transaction loThe DELETE statement removes rows one at a time                       and records an entry in the transaction log for each deleted row
If the table contains an identity column, the counter for that column is reset to the seed value that is defined for the columnDELETE retain the identity
Restrictions on using Truncate Statement
1. Are referenced by a FOREIGN KEY constraint.
2. Participate in an indexed view.
3. Are published by using transactional replication or merge replication.
Delete works at row level, thus row level constrains apply

Wednesday, 10 October 2012

String Handling in JAVA

String Handling is an important part of any programming language.
Strings are widely used in JAVA Programming, are a sequence of characters. String Class is defined in java.lang package so it is implicitly available for all programs

String class has following features:-
  • It is Final class
  • Due to Final, String class can not be inherited.
  • It Extends object class.
  • It implements Serializable, Comparable and CharSequence interfaces.
  • It is immutable.
  • It is also a datatype in java

String Example 1:Creating new String
String a=”Ashish”; 
String b=new String(); 
String c=new String(“Ashish”);

String Example 2:Comparing String
String a=”Ashish”;
String b=”Ashish”;
String c=new String(“Ashish”);
if(a==b) System.out.println(“Same reference “); 
if(a==c) System.out.println(“Same Reference of A and C “); 
else System.out.println(“Not Same Reference “);

There are two ways to create a String object in Java- 
1.Using the new operator. For example, 
String str1 = new String("Ashish");. 
2.Using a string literal. For example, 
String str2="Ashish"; (string literal) 

But these both "Ashish" have different reference. So if we compare str1 & str2, this is not equal. because str1 is created using new operator.

This diagram show the difference-

String Class Methods & Example
Click here

StringBuffer Class in JAVA
The java.lang.StringBuffer classes should be used when you have to make a lot of modifications to strings of characters. As,String objects are immutable , so if you choose to do a lot of manipulations with String Objects, you will end up with a lot of abandoned String objects in the String pool.

StringBuffer Example
StringBuffer sb=new StringBuffer(“Hiiii”);
System.out.println(sb); //HiiiiJavacup

Example for Thread Priorities in Java

class MyThread1 extends Thread{
MyThread1(String s){


public void run(){
for(int i=0;i<3;i++){
Thread cur=Thread.currentThread();
int p=cur.getPriority();
System.out.println("Thread Name  :"+Thread.currentThread().getName());
System.out.println("Thread Priority  :"+cur);


class MyThread2 extends Thread{
MyThread2(String s){


public void run(){
for(int i=0;i<3;i++){
Thread cur=Thread.currentThread();
int p=cur.getPriority();
System.out.println("Thread Name  :"+Thread.currentThread().getName());
System.out.println("Thread Priority  :"+cur);


public class ThreadPriority{
public static void main(String args[]){
MyThread1 m1=new MyThread1("My Thread 1");
MyThread2 m2=new MyThread2("My Thread 2");



Tuesday, 9 October 2012

Still three subjects are remaining.:(

Date validation in lex

int i=0,yr=0,valid=0;
([0-2][0-9]|[3][0-1])\/(([0]?(1|3|5|7|8))|(10|12))\/([1-2][0-9][0-9][-0-9]) {valid=1;}

([0-2][0-9]|30)\/((0(4|6|9))|11)\/([1-2][0-9][0-9][0-9]) {valid=1;}

([0-1][0-9]|2[0-8])\/[0]?2\/([1-2][0-9][0-9][0-9]) {valid=1;}

29\/[0]?2\/([1-2][0-9][0-9][0-9]) { while(yytext[i]!='/')i++; i++;while(yytext[i]!='/')i++;i++;while(i<yyleng)yr=(10*yr)+(yytext[i++]-'0'); if(yr%4==0||(yr%100==0&&yr%400!=0))valid=1;}

printf("Enter the Date(DD-MM-YY");
if(valid==1) printf("It is a valid date\n");
else printf("It is not a valid date\n");

Sunday, 7 October 2012

Fedora Workshop

From last night game
I came to know the if you have confidence about yourself and your mates
there is no chance of loosing the  any chance .
You will be the winner for any race.
I salute to West Indies team for their wonderful performance throughout the series.