Technology Questions

A record data type represents a data type for that row in a database table. It lets u define your own records and not your own fields.

Cursors help you manipulate the information retrieved by select statements. This can be done by assigning a name to the cursor.

Example:

CURSOR emp_cur 

IS 

SELECT emp_number from employee_tbl where employee_name = name_in;

Types of Cursors:

Implicit cursors- These cursors are not declared by the programmer. They are issued when the SQL statement is executed. The open, close and fetching is done by itself.

Example:

UPDATE employee SET salary = salary * 2.1;

Here, an implicit cursor is issued to identify the set of rows in the table which would be affected by the update.

Explicit cursors- These cursors are defined by programmer. They are used in queries that return multiple rows.

Example:

CURSOR emp_cur 

IS 

SELECT emp_number from employee_tbl where employee_name = name_in;

String class objects are immutable objects and they represents strings( sequence of characters)

StringBuffer class objects are mutable objects representing strings and they are Thread safe

StringBuild class objects are also mutable objects representing strings and they are not Thread safe

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.

The JVM performs three main tasks:

• Loads code

• Verifies code

• Executes code

Array is collection of same data type. Array size is fixed, It cannot be expanded.

But ArrayList is a growable collection of objects.ArrayList is a part of Collections Framework and can work with only objects.

- The Dictionary class is an abstract class.

- Classes like Hashtable which map keys to values inherit from this class. 

- An object can be looked for if a dictionary and a key is provided.

- Any non-null object can be used as a key and as a value.

XML, Extensible Markup Language, is an open, text based markup language that provides structural and semantic information to data. XML is a metalanguage that can be used to create other language. It is used to structure and describe data that can be understood by other applications. Using XML, we can separate the user interface from data.

Features of XML :

- XML is a generalized markup language that means one can define his/her own tag sets.

- A valid XML document contains rules and is self-describing.

- The rules that are found in DTD allow the documents to be validated.