class ImplementsRunnable implements Runnable {
private int counter = 0;
public void run() {
counter++;
System.out.println("ImplementsRunnable : Counter : " + counter);
}
}
class ExtendsThread extends Thread {
private int counter = 0;
public void run() {
counter++;
System.out.println("ExtendsThread : Counter : " + counter);
}
}
public class ThreadVsRunnable {
public static void main(String args[]) throws Exception {
//Multiple threads share the same object.
ImplementsRunnable rc = new ImplementsRunnable();
Thread t1 = new Thread(rc);
t1.start();
Thread.sleep(1000); // Waiting for 1 second before starting next thread
Thread t2 = new Thread(rc);
t2.start();
Thread.sleep(1000); // Waiting for 1 second before starting next thread
Thread t3 = new Thread(rc);
t3.start();
//Creating new instance for every thread access.
ExtendsThread tc1 = new ExtendsThread();
tc1.start();
Thread.sleep(1000); // Waiting for 1 second before starting next thread
ExtendsThread tc2 = new ExtendsThread();
tc2.start();
Thread.sleep(1000); // Waiting for 1 second before starting next thread
ExtendsThread tc3 = new ExtendsThread();
tc3.start();
}
} ImplementsRunnable : Counter : 1
ImplementsRunnable : Counter : 2
ImplementsRunnable : Counter : 3
ExtendsThread : Counter : 1
ExtendsThread : Counter : 1
ExtendsThread : Counter : 1
JDBC
|
Hibernate
|
With JDBC, developer has to write code to map an
object model's data representation to a relational data model and its
corresponding database schema.
|
Hibernate is flexible and powerful ORM solution to
map Java classes to database tables. Hibernate itself takes care of this
mapping using XML files so developer does not need to write code for
this.
|
With JDBC, the automatic mapping of Java objects
with database tables and vice versa conversion is to be taken care of by
the developer manually with lines of code.
|
Hibernate provides transparent persistence and
developer does not need to write code explicitly to map database tables
tuples to application objects during interaction with RDBMS.
|
JDBC supports only native Structured Query
Language (SQL). Developer has to find out the efficient way to access
database, i.e. to select effective query from a number of queries to
perform same task.
|
Hibernate provides a powerful query language
Hibernate Query Language (independent from type of database) that is
expressed in a familiar SQL like syntax and includes full support for
polymorphic queries. Hibernate also supports native SQL statements. It
also selects an effective way to perform a database manipulation task for
an application.
|
Application using JDBC to handle persistent data
(database tables) having database specific code in large amount. The code
written to map table data to application objects and vice versa is
actually to map table fields to object properties. As table changed or
database changed then it’s essential to change object structure as well as
to change code written to map
table-to-object/object-to-table.
|
Hibernate provides this mapping itself. The actual
mapping between tables and application objects is done in XML files. If
there is change in Database or in any table then the only need to change
XML file properties.
|
With JDBC, it is developer’s responsibility to
handle JDBC result set and convert it to Java objects through code to use
this persistent data in application. So with JDBC, mapping between Java
objects and database tables is done manually.
|
Hibernate reduces lines of code by maintaining
object-table mapping itself and returns result to application in form of
Java objects. It relieves programmer from manual handling of persistent
data, hence reducing the development time and maintenance cost.
|
With JDBC, caching is maintained by hand-coding.
|
Hibernate, with Transparent Persistence, cache is
set to application work space. Relational tuples are moved to this cache
as a result of query. It improves performance if client application reads
same data many times for same write. Automatic Transparent Persistence
allows the developer to concentrate more on business logic rather than
this application code.
|
In JDBC there is no check that always every user
has updated data. This check has to be added by the developer.
|
Hibernate enables developer to define version type
field to application, due to this defined field Hibernate updates version
field of database table every time relational tuple is updated in form of
Java class object to that table. So if two users retrieve same tuple and
then modify it and one user save this modified tuple to database, version
is automatically updated for this tuple by Hibernate. When other user
tries to save updated tuple to database then it does not allow saving it
because this user does not have updated data.
|
<load-on-startup>non-zero-integer</load-on-startup>
tag using the deployment descriptor web.xml. This makes the java
servlet to be loaded and initialized when the server starts. This
process of loading a java servlet before receiving any request is called
preloading or preinitialization of a servlet.<servlet>
<servlet-name>Servlet-URL</servlet-name>
<servlet-class>com.javapapers.Servlet-Class</servlet-class>
<load-on-startup>2</load-on-startup>
</servlet>