TOP 10 you need to know about MEACHINE LEARNING (ML) | Interview Ready

What is Java?

Java is the high-level, object-oriented, robust, secure programming language, platform-independent, high performance, Multithreaded, and portable programming language. It was developed by James Gosling in June 1991. It can also be known as the platform as it provides its own JRE and API.

Java applications

1. Mobile Applications
2. Desktop GUI Applications
3. Web-based Applications
4. Enterprise Applications
5. Scientific Applications
6. Gaming Applications
7. Big Data technologies
8. Business Applications
9. Distributed Applications
10. Cloud-based Applications

JVM

JVM(Java Virtual Machine) acts as a run-time engine to run Java applications. JVM is the one that actually calls the main method present in a java code. JVM is a part of JRE(Java Runtime Environment).

Java applications are called WORA (Write Once Run Anywhere). This means a programmer can develop Java code on one system and can expect it to run on any other Java-enabled system without any adjustment. This is all possible because of JVM.

Java Runtime Environment(JRE)

The Java Runtime Environment, or JRE, is a software layer that runs on top of a computer’s operating system software and provides the class libraries and other resources that a specific Java program needs to run.

Java Development Kit(JDK)

The Java Development Kit, or JDK, is a set of tools for developing Java applications. Developers choose JDKs by Java version and by package or edition—Java Enterprise Edition (Java EE), Java Special Edition (Java SE), or Java Mobile Edition (Java ME). Every JDK always includes a compatible JRE, because running a Java program is part of the process of developing a Java program.

What are the Characteristics of Java?

1. Java is simple.
2. Object-Oriented.
3. Platform Independent.
4. Secure.
5. Robust.
6. Architectural Neutral.
7. Portable.
8. Performance.

Object oriented Programming

Object means a real-world entity such as a pen, chair, table, computer, watch, etc. Object-Oriented Programming is a methodology or paradigm to design a program using classes and objects.

Encapsulation

The meaning of Encapsulation, is to make sure that "sensitive" data is hidden from users. To achieve this, you must declare class variables/attributes as private provide public get and set methods to access and update the value of a private variable

Java Inheritance (Subclass and Superclass)

In Java, it is possible to inherit attributes and methods from one class to another. We group the "inheritance concept" into two categories:

subclass (child) - the class that inherits from another class

superclass (parent) - the class being inherited from

To inherit from a class, use the extends keyword.

Java Polymorphism

A person at the same time can have different characteristics. Like a man at the same time is a father, a husband, an employee. So the same person possesses different behavior in different situations. This is called polymorphism. 

Polymorphism is considered one of the important features of Object-Oriented Programming. Polymorphism allows us to perform a single action in different ways. In other words, polymorphism allows you to define one interface and have multiple implementations. The word “poly” means many and “morphs” means forms, So it means many forms.

In Java polymorphism is mainly divided into two types: 

1. Compile-time Polymorphism
2. Runtime Polymorphism

Abstract Classes and Methods

Data abstraction is the process of hiding certain details and showing only essential information to the user.

Abstraction can be achieved with either abstract classes or interfaces 

The abstract keyword is a non-access modifier, used for classes and methods:

Abstract class: is a restricted class that cannot be used to create objects (to access it, it must be inherited from another class).

Abstract method: can only be used in an abstract class, and it does not have a body. The body is provided by the subclass (inherited from).

Data Types in Java

Data types specify the different sizes and values that can be stored in the variable. There are two types of data types in Java:

Primitive data types: The primitive data types include boolean, char, byte, short, int, long, float and double.

Non-primitive data types: The non-primitive data types include Classes, Interfaces, and Arrays.

Operators in Java

Operator in Java is a symbol that is used to perform operations. For example: +, -, *, / etc.

There are many types of operators in Java which are given below:

1. Unary Operator,
2. Arithmetic Operator,
3. Shift Operator,
4. Relational Operator,
5. Bitwise Operator,
6. Logical Operator,
7. Ternary Operator and
8. Assignment Operator.

control statements

1. Java provides three types of control flow statements.
2. Decision Making statements
3. if statements
4. switch statement
5. Loop statements
6. do while loop
7. while loop
8. for loop
9. for-each loop
10. Jump statements
11. break statement
12. continue statement
13.  Selection statements

In java, the selection statements are also known as decision making statements or branching statements or conditional control statements. The selection statements are used to select a part of the program to be executed based on a condition. Java provides the following selection statements.

if statement

if-else statement

nested if statement

if-else if statement

switch statement

Iteration statements

while statement

do-while statement

for statement

for-each statement

Jump statements

Jumping statements are control statements that transfer execution control from one point to another point in the program. There are two Jump statements that are provided in the Java programming language:

Break statement.

Continue statement.

1. Using Break Statement to exit a loop:

In java, the break statement is used to terminate the execution of the nearest looping statement or switch statement. The break statement is widely used with the switch statement, for loop, while loop, do-while loop. 

Syntax: break;

2. Use Break as a form of goto

Java does not have a goto statement because it produces an unstructured way to alter the flow of program execution. Java illustrates an extended form of the break statement. This form of break works with the label. The label is the name of a label that identifies a statement or a block of code.

Syntax: break label; Continue Statements

The continue statement pushes the next repetition of the loop to take place, hopping any code between itself and the conditional expression that controls the loop.