Technology Questions

-The shift() method is similar as the pop() method but the difference is that Shift method works at the beginning of the array. 

-The shift() method take the first element off of the given array and returns it. The array on which is called is then altered.

For example

var myarray = ["apple ", "banana ", "mango "]; 

console.log(myarray.shift());

console.log(myarray);

we get the following console output:

apple

["banana ", "mango "];

When we call shift() on an empty array, it will return an undefined value.

- The Set interface provides methods for accessing the elements of a finite mathematical set

- Sets do not allow duplicate elements

- Contains no methods other than those inherited from Collection

- It adds the restriction that duplicate elements are prohibited

- Two Set objects are equal if they contain the same elements

abstract method is a method declared with abstract modifier but  with out body.

The android system will keep all the process that are hosting the services together at one place till the time the service is not started or connected to the client. The priority of the process is divided when running low on memory or when the process has to be killed. The process lifecycle is as follows:
- The service is running currently then the methods onCreate(), onStartCommand(), and onDestroy()methods, will run in the foreground to execute the process without being killed.
- The service is already started then the process can be considered as less important then the processes that are currently visible and used. This is done as there are only few processes that are visible to the users on the screen.
- The clients are bounded to the services they are providing requires more priority in the execution list.
- The service that is started uses startForeground(int, Notification)API to allow all the services to run in the foreground state. The system considers only the services where the user is still active as the services not to be killed.

Various elements of OOP are:

• Object

• Class

• Method

• Encapsulation

• Information Hiding

• Inheritance

• Polymorphism

Two types of classes:

1) Top Level Class

2) Classes within Class

       i) member classes

             a) static member class

             b) non static member class

      ii) local classes

      iii) anonymous classes

BDC ----> Batch Data Communication 

Methods of BDC-----> Direct Input method, Batch Input Session method, Call transaction method.

A stored procedure is a segment of declarative SQL statements stored inside the database catalog. A stored procedure can be invoked by triggers, other stored procedures or applications such as Java, C#, PHP, etc.

Advantages 

- Typically stored procedures help increase the performance of the applications. Once created, stored procedures are compiled and stored in the database. However MySQL implements the stored procedures slightly different. MySQL stored procedures are compiled on demand. After compiling a stored procedure, MySQL puts it to a cache. And MySQL maintains its own stored procedure cache for every single connection. If an application uses a stored procedure multiple times in a single connection, the compiled version is used, otherwise the stored procedure works like a query.

- Stored procedures helps reduce the traffic between application and database server because instead of sending multiple lengthy SQL statements, the application has to send only name and parameters of the stored procedure.

- Stored procedures are reusable and transparent to any applications. Stored procedures expose the database interface to all applications so that developers don’t have to develop functions that are already supported in stored procedures.

- Stored procedures are secure. Database administrator can grant appropriate permissions to applications that access stored procedures in the database without giving any permission on the underlying database tables.

Disadvantages

- If you use a lot of stored procedures, the memory usage of every connection that is using those stored procedures will increase substantially. In addition, if you overuse a large number of logical operations inside store procedures, the CPU usage will also increase because database server is not well-designed for logical operations.

- A constructs of stored procedures make it more difficult to develop stored procedures that have complicated business logic.

- It is difficult to debug stored procedures. Only few database management systems allow you to debug stored procedures. Unfortunately, MySQL does not provide facilities for debugging stored procedures.

-It is not easy to develop and maintain stored procedures. Developing and maintaining stored procedures are often required specialized skill set that not all application developers possess. This may lead to problems in both application development and maintenance phases.