Inversion of Control (IoC)

Inversion of control is a common characteristic of frameworks. As the name suggests it inverts something. So, What aspect of control it is inverting?

Early user interfaces were controlled by the application program. You can see commands like “Enter name”, “Enter address”; Your program would drive the prompts and pick up a response to each one. The main control of the program was inverted, moved away from you to the framework.

The inversion is about how we lookup a plugin implementation. The approach that these containers use is to ensure that any user of a plugin follows some convention that…

Servlet

A servlet is a small Java program that runs within a Web server. Servlets receive and respond to requests from Web clients, usually across HTTP, the HyperText Transfer Protocol.

We can implement 2 types of interface.

1. javax.servlet.GenericServlet
2. javax.servlet.http.HttpServlet

Life Cycle of Servlet

1. First servlet is constructed, and initialized with init method.
2. Any calls from clients to the service method are handled.
3. When servlet is out of service, then destroy method is called for garbage collection.

Methods of Servlet

1. void destroy()- Used to indicate a servlet is taken out of service.
2. ServletConfig getServletConfig()- Returns object of ServletConfig which contains initialization and…

Flex-box

Flexbox is also known as flexible box module. It is also known as one-dimensional layout module.

The two axes of flexbox:-

1. The main axis is defined by flex direction which have 4 values:-

a. row

b. row-reverse

c. column

d. column-reverse

Normalization is the way to organize data in database.

It is used to remove insertion, updation and deletion anomalies.

Normal form is used to reduce redundancy from the database.

Types of Normal Forms:-

1. First Normal Form:-

First criteria of 1NF is that table must contain atomic value.

Single attributes of a table can’t hold multiple values.

Time complexity

Time complexity is the computational complexity that describes the amount of computer time it takes to run an algorithm.

In simple words we can say that it tells how much time our program is taking to run.

Calculating time complexity:-

int i=0;

Here i variable is taking constant time. It is denoted as Big O or O(1).

for (int i = 0; i < n; ++i) {
    System.out.println(i);
}

In above for loop variable n will iterate through n times.

So Time complexity will be o(n).

Different Types of time complexity

1. Worst case time complexity:- Maximum number of times program…

In this blog we are going to see about collections in java. So collection is a framework in java by which we can do many predefined task by using predefined methods in collection framework.

Array:- When we want to store more than one elements inside one reference then we use array. But array has many disadvantages. Main disadvantage is that we can’t increase size of array. In starting itself we have to declare size of array.

Collection Framework:- It contains different classes and interfaces which can be used to represent a group of individual object into a single entity.

Hierarchy…

Object-Oriented Programming is a programming paradigm which is based on the concept of objects. Here objects contains 2 things data and code. Data can be in the form of fields. In other words fields can be called attributes or properties.

Concepts in Object-Oriented Programming

1. Object
2. Class
3. Inheritance
4. Encapsulation
5. Abstraction
6. Polymorphism

1. Object:

Objects are conceptually similar to real-world objects. They too consist of state and related behavior. An object stores it’s state in fields and exposes it’s behavior through methods. In Java we can create object using ‘new’ keyword.
Example:-

Output:-

Your room is Living Room

2. Class

A class is the blueprint…