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List of Free SCJA Articles from Ucertify.com |
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Written by Roger Stuart
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Page 9 of 9
An enumeration is a feature added to J2SE 5. It is very similar to a
class, except that it cannot be instantiated. It is declared using the
keyword enum. An enumeration can have constructors, methods, and
instance variables in the same way as a class. Identifiers of an enum
are referred to as... [read more..]
A roll back is an operation that returns a database to its previous
state (a state before a transaction). This ensures that a database
remains unaffected if a transaction fails. It plays an important role
in recovering a database in the event a database server crashes. [read more..]
A local variable is defined inside a block or a method. The lifetime of
such a variable is limited by the lifetime of the block in which it is
enclosed. It is necessary to initialize a local variable; otherwise, a
compile time error will occur. If the same name is used for an instance
variable as... [read more..]
Polymorphism is a feature that allows an interface in Java to be used
by many classes for different purposes. The word polymorphism combines
poly with morphism, which means many forms. Some examples of
polymorphism are overloading and overriding. Polymorphism allows an
interface to be used for a... [read more..]
The earlier version of Java did not contain any support for database
access. This was the major drawback of this language, as in today's
world, keeping and managing databases is quite important. To remove
this drawback, Sun Microsystems introduced a new interface known as
Java Database... [read more..]
A batch update is a process of combining multiple UPDATE, DELETE, or
INSERT statements into a single batch and having the whole batch sent
to the database and processed in one round. This is especially useful
with prepared statements when repeating the same statement with
different bind variables. [read more..]
The replace() method of the String class replaces a given character in
a given string with a new character. The general syntax for this method
is as follows: public String replace(char oldChar, char newChar) For
example, Sting s="Hello"; Now the following syntax will replace all
the... [read more..]
The not equal to operator is a boolean logical operator. It is denoted
by the != symbol. It compares two expressions and returns true if the
expression on the left hand side is not equal to the expression on the
right hand side, otherwise it returns false. [read more..]
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