Interview Questions

Autoboxing is the automatic conversion that the Java compiler makes between the primitive types and their corresponding object wrapper classes. For example, converting an int to an Integer, a double to a Double, and so on. If the conversion goes the other way, this is called unboxing. 

_VIEWSTATE is the command used to implement view state

Difference between undeclared and undefined variables is defined as

Undeclared variables are those that do not exist in a program and are not declared. If the program tries to read the value of an undeclared variable, then a runtime error is encountered.

Undefined variables are those that are declared in the program but have not been given any value. If the program tries to read the value of an undefined variable, an undefined value is returned.

Android uses Dalvik Virtual Machine (DVM) which requires a special bytecode. We need to convert Java class files into Dalvik Executable files using an Android tool called "dx". In normal circumstances, developers will not be using this tool directly and build tools will care for the generation of DVM compatible files.

With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often leads to significant errors.

AJAX uses four technologies, which are as follows:

       => JavaScript

       => XMLHttpRequest

       => Document Object Model (DOM)

       => Extensible HTML (XHTML) and Cascading Style Sheets (CSS)

BlackBerry Enterprise Server: The BlackBerry handhelds are integrated into the e-mail system of the organization through software BlackBerry Enterprise Server. The BES versions are available for MS Exchange, Novell GroupWise and Lotus Domino. A connector was made by Google for BES for making BES available for Google Apps. A new feature is added which enables to track the current location of an individual through trailateration.

BES provides handhelds with the connectivity of TCP/IP which can be accessed through a component known as “Mobile Data Service – Connection Service – MDS-CS. This allows the development of custom application development using data streams on BlackBerry devices which are based on the Sun JME platform.

BES also provides network security in the form of Triple DES or AES encryption standard of all data including e-mail and MDS traffic, which travels between the BlackBerry hand held devices and a BES.