Technology Questions

Intents are created to define an action that we want to perform and the launches the appropriate activity from another application.

Code

        Intent intent = new Intent(Intent.ACTION_SEND);

        intent.putExtra(Intent.EXTRA_EMAIL, recipientArray);

        startActivity(intent);

The JDBC Driver provides vendor-specific implementations of the abstract classes provided by the JDBC API. This driver is used to connect to the database.

Web browser is a software application used to locate,retrieve and display content on the World Wide Web, including Web pages, images, videos and other files.

Examples : Microsoft Internet Expiorer , Mozilla Firefox , Google Chrome, Opers , Safari etc...

These are accessibility modifiers. Private is the most restrictive, while public is the least restrictive. There is no real difference between protected and the default type (also known as package protected) within the context of the same package, however the protected keyword allows visibility to a derived class in a different package.

An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior and all methods are implicitly abstract. An interface has all public members and no implementation. An abstract class is a class which may have the usual flavors of class members (private, protected, etc.), but has some abstract methods.

ClassName refName = new ClassName();

or

ClassName refName;

refName = new ClassName();

Joins are used to combine data of one or more tables. Joins should be used when there is abundant data. Joins can be LEFT, RIGHT, OUTER, INNER or even SELF JOIN. The purpose is to bind data from multiple tables without any receptivity

Oracle NOT NULL is used on a column to ensure that the value for that column can never be NULL.
Example:
Below, the constraint is that the id should never be NULL. If it is, oracle throws an error.
create table employee ( id number NOT NULL, Name varchar(200) );