revature study

What is a getter/setter? What is their purpose?

Functions that modify private variables.

How do you select all tables in a database?

SELECT* FROM sys.Tables

or SELECT*FROMinformation_schema.tables

How do you link a style sheet to an html document?

By using the link element

Can we overload or override static methods in java?

Yes, we can overload static methods by having the same method but with different parameters in the sub class. No, we can't override a static method because static methods are done at compile time while method overriding only occurs at runtime.

What is override and overload?

Override is when you use the same method in a subclass but modify or add to it, while overload is when you use the same method in a subclass but you have a different number or type of parameters.

What is an SQL trigger?

They are stored programs that are automatically executed in response to an event, such as inserting a new row in a table.

Name and explain some elements in HTML

for creating hyperlinks,

to create a line break,

to create a heading

used to divide the page

used to create a paragraph

to create independent self contained content from rest of page

used to define the header section

used to define navigation area

used to define footer Area.;

Tell me about a project you recently worked on?

The last major project i worked on was a website for a arts and crafts business. I had to create an ecommerce website from scratch without using a CMS or anything like that. I had to create a products page and link that through php to a mySQL database, and then display all of the products, along with the price and shipping. I then had to include the total price and integrate a third party credit card processor. I also had to create a new login portal for customers that would show recent orders, save credit card information, and allow them to change their information.

What is DBMS?

Database management software. It allows users to create, read, update , and delete data in a database. It stores data in files. It consists of the data, the database engine that allows data to be accessed and modified,and the database schema, which defines the database's logical structure.

What is RBDMS?

Relational Database Management Software.

It stored data into columns and rows. SQL server is an example.

What does SQL stand for?

Structured Query Language

Who determines the standards for SQL?

The American National Standards Institute

What are the versions of SQL?

SQL-86 to SQL:2016

What are users vs schemas?

A schema is collection of database objects, including tables, views, sequences, stored procedures, etc. A user owns a schema.

What is CSS and how does it work?

Cascading style sheets. It styles the website by describing how the HTML elements are to be displayed.

How do you change the background color?

What are the different HTMl elements

html, head, title, body

What is doctype used for?

It tells the browser what version of markup language is being used.

How can you create a button in HTML?

My Button

How do you comment in HTML?

<!-- This is a single line comment -->

What is MVC?

Model View Controller

it consists of three parts"

one that is the visual part that users interact with - the view,

one that represents the object being modeled, and

something that manages data between the different parts - the controller.

What are selectors? List some

Patterns used to select the element you want to change. .class, #id, :visited.

What is a wireframe?

A visual guide that represents the skeletal framework of a website. Wireframes are created for the purpose of arranging elements to best accomplish a particular purpose.

What are HTML form methods?

Specifies which http protocol should be used when submitting form data. The options are Get and Post.

What is the box model?

A box that wraps around every HTML element. It consists of: margins, borders, padding, and the actual content.

How can you open a link in a new tab/browser window?

What is the correct HTML for making a drop-down list?

the element

Which input type defines a slider control?

Which HTML element is used to display a scalar measurement within a range?

The element

What is the syntax for referring to an external style sheet?

Which CSS property is used to change the text color of an element?

color

How do you make each word in a text start with a capital letter?

text-transform: capitalize;

What is the javascript syntax to change an element of an HTML page?

document.getElementById("demo").innerHTML = "Hello World!";

When using the padding property; are you allowed to use negative values?

No

How do you select all p elements inside a div element?

div p;

What is the syntax for creating a javascript array?

var colors = ["red", "green", "blue"];

What is a list, set, and map? When should you use each?

List interface is a ordered collection that allows duplicate and null values. We can get elements by index.

When there is a need to access elements frequently using the index, or when you want the elements stored to maintain the insertion order then use list.

A Set is an unordered collection that won't allow duplicate elements. It allows null elements, but we can't get elements by key or index .

When the collection should be of unique elements and no duplicates are tolerated, then go with "Set"

.

Map interface is a unordered collection that allows duplicate elements but not duplicate keys. It allows null elements but not null keys.

When the data stored should be in the form of key and value then use map.

Why doesn't java support multiple inheritance?

It supports it, just through interfaces. It doesn't support multiple inheritance in order to avoid the complexity and conflicts that result. For example, if more than one superclass has the same base class then the subclass will receive 2 copies of the same attributes and methods, leading to ambiguity.

Is Javascript case sensitive?

Yes

Why are strings immutable?

When a string is created and if the string already exists in the pool, the reference of the existing string will be returned, instead of creating a new object and returning its reference. If a string is mutable, changing the string with one reference will lead to the wrong value for the other references.

It would also lead to security issues, since strings are often used in the parameters for database connections, opening a file, network connections, etc. If strings were mutable those values could be changed and it would be a security risk.

It would also make hashmaps much less efficient, since they would have to check the hashcode every time it was used.

what is a try, catch and what purpose does finally serve?

A try statement is used to catch exceptions that might be thrown as your program executes. You should use a try statement whenever you use a statement that might throw an exception

A try block is always followed by a catch block, which handles the exception that occurs in the try block.

A finally block contains all the crucial statements that must be executed whether an exception occurs or not.

type an object declaration

String mystring = new String();

What is normalization?

A process which involves organizing the fields and tables of a database to eliminate data redundancy and Insertion, Update and Deletion Anomalies.

Why is the main method static in java?

Static allows main() to be called before an object of the class has been created. This is necessary because main() is called by the JVM before any objects are made. Since it is static it can be directly invoked via the class.

What does static mean?

Means that the variable or function is shared between all instances of that class as it belongs to the type, not the actual objects themselves. So if you have a variable: private static int i = 0; and you increment it ( i++ ) in one instance, the change will be reflected in all instances.

What are the four pillars of oop?

Abstraction,Polymorphism, Encapsulation, Inheritance

What is object oriented programming?

A design philosophy based on objects which contain data in attributes and code in the form of methods. Objects are an instance of a class, which is a template for creating objects.

What is a constructor?

a block of code similar to a method that's called when an instance of an object is created.

How do you create a new constructor?

public Actor(String first, String last)

{

firstName = first;

lastName = last;

}

Actor a = new Actor("Arnold", " Schwarzenegger");

What is inheritance? What are the different types?

The mechanism by which one class inherits the attributes and methods of another class.

Single Inheritance: A Subclass inherits methods and attributes from one superclass.

Multilevel Inheritance: a derived class will be inheriting a base class and the derived class also acts as the base class for other class.

Hierarchical Inheritance: Multiple subclasses inherit from one superclass.

Multiple Inheritance: One class can inherit from more than one superclass. In java we must do this through interfaces.

A subclass can only have one superclass

Subclass doesn't inherit private fields or methods