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JDBC allows java applications to connect to relational databases. Database can be reside in local, network or cloud. JDBC Features Provide portable access to various databases Can build custom sql statements JDBC Supported Databases MySQL Oracle DB2 PostgreSQL Key Classes of JDBC java.sql.DriverManager java.sql.Connection java.sql.Statement java.sql.ResultSet java.sql.DataSource JDBC Development Process Get a connection to the database ex :  jdbc:<driver protocol>:<driver connection details> Create a statement object Execute the Query Process the result set

Object Object is an entity that has state and behavior Class Collection of objects is known as class. There are four main types of OOP concepts Inheritance Object acquire all the properties and behavior of parent object Improve code re-usability Polymorphism One task is performed by different ways Use method overload and override Abstraction Hiding internal details and showing functionality Use abstract class and interfaces Encapsulation Binding code and data into a single unit

JEE stands for Java Enterprise Edition. JEE can use for business, web, client and information applications. JEE Applications Web components - JSP,Servlets Web services - JAX/WS, JAX/RS Data access in Java - JDBC/JPA Persist and entities and enterprise Java beans To create JEE project in Eclipse  Create Dynamic Web Project Under the web contents create your web pages (html files) You can use Apache Tomcat server to deploy your web application. To change URL  To change the URL of servlets that you have built, you have to configure web.xml file. As an example, you have to add following lines to your web.xml file   <servlet>   <servlet-name>helloworld</servlet-name>   <servlet-class>com.amali.surverlet.HelloWorld</servlet-class>   </servlet>   <servlet-mapping>   <servlet-name> helloworld</servlet-name>   <url-pattern>/hidden/hello.do</url-pattern>   </servlet-mapping> I

Java Applications  There are mainly four types of Java applications. Standalone Web  Enterprise  Mobile Java Features  There are several features in Java, but in here listed some important ones Platform independent Object oriented Multi threaded Distributed Robust (automatic garbage collection, exception handling, type checking) Java Security  Java has 3 built-in security components; Classloader: Separate class files packages from imported packages. BytecodeVerifier: check the illegal access to objects Security Manager: check what resources can access the object. C++ vs Java Methods Static - No need to create an object to invoke the static method. Constructor - use to initialize objects Constructor name must same as the class name Constructor has no return type There are two types of constructors Default - no parameter Parameterized If there is no constructor defined in the class, compiler automatically create default construc

Hibernate is an ORM (Object Relational Mapping) tool which is primarily used in the data layer. Object Relational Mappings Problems There are several problems can occur when you are trying to save objects in the database from the scratch without using Hibernate. Mapping member variables to columns Mapping relationships Handling data types Managing changes to an object Set Up the Development Environment  Following steps are briefly pointed out how to set up Hibernate on your local machine. Download the hibernate jar files Create a project in Eclipse Right click on the project name and go to properties Navigate to libraries tab Add library and import jar files (lib-> JPA/required) Add Postgres JDBC driver as jar file Configurations After you set up the Hibernate you have to create hiberante.cfg.xml file and do some configurations like setup database details, entity class, etc. Dialect: Define what kind of language should use to talk to database Ann

Here are some popular tips in Java General Question JVM - Java Virtual Machine. Used to execute byte code. Platform dependent (but byte code is platform independent) JRE- Java Run time Environment. It provides run time environment and it's the implementation of JVM. It contains libraries and files that need to execute JVM.   JDK- Java Development Kit. It contains JRE and development tools. Why java doesn't support pointers: It's insecure and complex to understand We can save java file with another name if class is not defined as public Java use camalCase notation for objects naming (ex: firstName) OOP Concepts Related  Aggregation: weak relationship (bike has an indicator) Composition:  strong relationship (bike has an engine) GUI Java GUI - Install Window builder to create GUI using Eclipse IDE Code Related No issues when you write static public void instead of public static void We can execute program without main method : using static block