**Basics in Java**

OOP:

• It is the core of Java.
• It has four types Encapsulation,Inheritance,polymorphism,abstraction.

Abstraction:

• It is used to hide certain details and show essential features of the object.
• A powerful way to manage abstraction is through the use of hierarchical classifications.

Encapsulation:

• It is a mechanism of wrapping data (variables) and code acting on the data (methods) together as a single unit.

Inheritance:

• One object acquires all the properties and behaviors of an object
• create a new class that built upon the existing new class.
• Inherited class is called parent class or super class and new class is called child class or sub class.

Polymorphism:

• It is the ability of an object to form many forms.
• Parent class reference extends to child class reference.
• An object that can pass more than one IS-A test is polymorphic.

Entering the program in java:

• source file is very important.
• source file is a compilation unit.
• It contains one or more class definitions.
• dot java file name extensions is applied
• file name corresponds to class names may seem arbitary.

24/7/17

Closer Look at Program:

• It supports three styles of comments such as multiline comment,single line comment and document comment.
• Multiline - It shows at the top of the program.(longer remarks)
• This comment begins with /* and ends with */.Anything between this lines ignored by the compiler.
• It use class object without any instance class of the object such as keyword class.
• Single line - It begins with // and ends with the end of line.(line by line descriptions)

• Document

• main()-starting place of the program

• println()-display the string which passed to it.

• system.out-

• system-predefined class that provides access to the system.

• out-output stream connected to console.

• All statements in java ends with semicolon.

• First } ends the main function and next } ends the class definitions.

If statements:

• Condition is a boolean expression.If condition is true it is executed or else it is bye passed.

For loop:

• For loop contains iteration,initialization,condition of these three statements.

Literal:

• A constant value is represented by literal
• x is an character constant
• 100 is integer
• "sub" is an string