Prelims Flashcards by Thirdy Garcia

Who created JAVA and when?

James gosling et.al at sun microsystems, 1991

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What was the initial name of java?

Oak, it was changed to java because there is already a programming lang named oak

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The motivation for java is the need for platform independent language that could be embedded in various electronic products.

True

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One of the first projects developed in java

A personal hand held remote control named star 7

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The java technology is

A programming language
Deployment environment
Application environment
Development environment

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As a programming language, Java can create all
kinds of applications that you could create using
any conventional programming language.

True

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As a development environment, Java technology provides
you with a large suite of tools which are?

Interpreter
Compiler
documentation generator
class file packaging tool

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Java technology applications are typically general-
purpose programs that run on any machine where
the Java runtime
environment (JRE) is installed.

True

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Two main deployment environments

JRE supplied by java 2 software development kit, and on the web browser

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contains the complete set
of class files for all the Java technology packages,
which includes basic language classes, GUI
component classes, and so on.JRE supplied by java 2 software development kit,

JRE supplied by java 2 software development kit

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Code for printing output in Java

System.out.println(“ “);

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Phases of java program

Editor - compiler - interpreter

(Write, compile, run)

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Features of java

Java virtual machine ( JVM)
Garbage collection
Code security

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An implementation - Its implementation is
known as JRE (Java Runtime Environment).

True

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Whenever you write java
command on the command prompt to run the
java class, an instance of JVM is created.

True

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Responsible for freeing any memory that could be freed. Happens automatically.

Garbage collection

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It is attained in java through the implementation of the java runtime environment

Code security

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Runs code for a JVM and performs class loading

Java runtime environment (JRE)

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Responsible for loading all classes needed for java program.

Class loader

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Adds security by separating namespaces for the classes of local file system

Class loader

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Tests the format of the code fragments and checks the code fragments for illegal codes

Bytecode verifier

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programming
style which is associated with the concepts like
class, object, Inheritance, Encapsulation,
Abstraction, Polymorphism.

Object oriented programming

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Traditional procedural-oriented programming
languages (such as C, Fortran, Cobol and Pascal)
suffer some notable drawbacks in
creating reusable software components.

True

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Functions are less reusable.

True

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about writing procedures or methods that perform operations on the data,

Procedural programming

about creating objects that contain both data and methods.

Object oriented programming

Procedural programming has several advantages over object oriented programming

False

The problem solving phases

1. Analysis 2. General solution 3. Verify

Procedural programming Features

- top down design - limited code reuse - complex code - global data focused

Object oriented programming features

- object focused - code reuse - complex design - protected data

Advantages of OOP

- faster and easier to execute - provides clear structure for programs - helps keep the java code dry and easy to modify

What does DRY means

Don't repeat yourself

What is the basic unit of OOP

Class

Two main aspects of object oriented programming

Classes and objects

like an object constructor, or a “blueprint” for creating objects.

Class

The keyword for creating a new class

class

The keyword for creating a new object

new

To create a new object, you should:

specify the class name, followed by the object name, and use the keyword new

With objects and classes, You can use the existing class created.

True

Creating objects with classes process

Declaration, instantiation, initialization

OP languages permit higher level of abstraction for solving real-life problems.

True

An object oriented program consists of many well incapsulated objects

True

Benefits of OOP

Ease in software design, easy in maintenance, resuable software

a definition of objects of the same kind. it is a blueprint, template, or prototype that defines and describes the static attributes and dynamic behaviors common to all objects of the same kind

Class

realization of a particular item of a class. In other words, an instance is an instantiation of a class

Instance

The term usually refers to

Instance

A Class is a 3-Compartment Box Encapsulating Data and Operations

True

identifies the class.

Name

contains the static attributes of the class

Variables

contains the dynamic behaviors of the class.

Methods

frequently instantiate objects that use the objects of other classes (and their data and methods). Sometimes you write classes that do both.

Application classes

The principle used in creating private access is sometimes called

Information hiding

_________ in Java is a mechanism to encapsulate a group of classes, sub packages and interface

Package

What are the uses of package

1. Preventing naming conflicts. 2. Making searching/locating and usage of classes, interfaces, enumerations and annotations easier 3. Providing controlled access: protected and default have package level access control. 4. Packages can be considered as data encapsulation (or data-hiding).

Two categories of packages in JAVA

Built in packages (from java API) And user defined packages

The library is divided into _______ and _________

Packages and classes

Syntax for importing a single class

import package.name.Class;

Syntax for importing a whole package

import package.name.*;

___________ is used to process the input and produce the output.

Java (I/O) input and output

contains all the classes required for input and output operations.

java.io package

Standard output stream

System.out

Standard input stream

System.in

Standard error stream

System.err

Java application uses an _________ to write data to a destination; it may be a file, an array, peripheral device or socket.

Output stream

Java application uses an ___________ to read data from a source; it may be a file, an array, peripheral device or socket.

Input stream

used to get user input, and it is found in the java.util package.

Scanner class

These are notes written to a code for documentation purposes.

Java comments

Three types of comments

Single line, multi line, documentation

tokens that represent names of variables, methods, classes, etc

Java identifiers Note: they are case sensitive and must begin with a $, and they are case sensitive.

predefined identifiers reserved by Java for a specific purpose.

Java keywords

Tokens that do not change and are constant.

Java Literals

Different types of Java literals:

- Boolean - integer - floating-point - character - string

It may come in different formats: Decimal (base 8) Hexadecimal (base 16) Octal (base 8)

Integer literals

It represents decimals with fractional parts, and can be expressed in scientific notation

Floating-point literals

They have two values, true or false

Boolean

Represent single Unicode characters.

Character literal

Represent multiple characters and enclosed with quotation marks.

String literals

The java programming language defines eight primitive data types which include:

Boolean, char, byte, short, int, long, double, float

an item of data used to store the state of objects.

Variable

A variable has a ________ and ________

Data type, name

indicates the type of value that the variable can hold.

Data type

Declaring a variable syntax

[= initial value];

Two types of variables in java

Primitive and reference

Stores data in the actual memory location where the variable is

Primitive variable

Variables that store address in the memory location, points to another location

Reference variables

What are the different types of operators

Arithmetic, relational, logical, conditional

Compares two values and determines the relationship between the two values

Relational operators

They have one or two Boolean operands that yield a Boolean result.

Logical operators

A ternary operator that takes in three arguments

Conditional operator

The structure of an expression using a conditional operator

exp1?exp2:exp3

Evaluated from left to right

Compound condition

It is a sequence of data. Composed of bytes. Used by java to make I/O operation fast.

Stream

Prelims Flashcards

(92 cards)