Java Questions

The classloader is a subsystem of JVM that is used to load classes and interfaces.There are many types of classloaders e.g. Bootstrap classloader, Extension classloader, System classloader, Plugin classloader etc.

Cloning refers to creating duplicate copies of objects in java.

Shallow Cloning: Shallow cloning is a bitwise copy of an object. New object is created which is an exact copy that of the original one. In case any objects are referring the fields of these objects, just the references are copied.

Deep Cloning: In deep cloning, complete duplicate copy of the original copy is created. Deep cloning creates not only the primitive values of the original objects but also copies all its sub objects as well.

Clonable interface is used to perform cloning in java.

There are mainly four type of JDBC drivers available. They are:

Type 1 : JDBC-ODBC Bridge Driver - A JDBC-ODBC bridge provides JDBC API access via one or more ODBC drivers. Note that some ODBC native code and in many cases native database client code must be loaded on each client machine that uses this type of driver. Hence, this kind of driver is generally most appropriate when automatic installation and downloading of a Java technology application is not important. For information on the JDBC-ODBC bridge driver provided by Sun.

Type 2: Native API Partly Java Driver- A native-API partly Java technology-enabled driver converts JDBC calls into calls on the client API for Oracle, Sybase, Informix, DB2, or other DBMS. Note that, like the bridge driver, this style of driver requires that some binary code be loaded on each client machine.

Type 3: Network protocol Driver- A net-protocol fully Java technology-enabled driver translates JDBC API calls into a DBMS-independent net protocol which is then translated to a DBMS protocol by a server. This net server middleware is able to connect all of its Java technology-based clients to many different databases. The specific protocol used depends on the vendor. In general, this is the most flexible JDBC API alternative. It is likely that all vendors of this solution will provide products suitable for Intranet use. In order for these products to also support Internet access they must handle the additional requirements for security, access through firewalls, etc., that the Web imposes. Several vendors are adding JDBC technology-based drivers to their existing database middleware products.

Type 4: JDBC Net pure Java Driver - A native-protocol fully Java technology-enabled driver converts JDBC technology calls into the network protocol used by DBMSs directly. This allows a direct call from the client machine to the DBMS server and is a practical solution for Intranet access. Since many of these protocols are proprietary the database vendors themselves will be the primary source for this style of driver. Several database vendors have these in progress.

AWT are heavy-weight componenets. Swings are light-weight components. Hence swing works faster than AWT.

The diamond problem is an ambiguity that can occur when a class multiply inherits from two classes that both descend from a common super class

Encapsulation describes the ability of an object to hide its data and methods from the rest of the world 

Static member class is a class defined inside outer class with static modifier.

EX:

Class A {  //top level class or outer class

    .....

    static class B {  //static member class

    }

   .....

}