Learn Java language fundamentals with Unit nexus

Java Language Fundamentals / 1 of 28
Java Language Fundamentals
Session 2

Objectives
 Interpret the Java program
 Understand the basics of the Java language
 Identify data types

Java Program Structure
 Environment Information
 Class Declaration
 Tokens:
 Identifiers
 Keywords / Reserve words
 Separators
 Literals
 Operators

Sample Java program

Compiling and executing the
sample program

Passing Command Line
Arguments (1)

Passing Command Line
Arguments (2)

Basics of the Java Language
 Classes & Methods
 Data types
 Variables
 Operators
 Control structures

Classes in Java
 Class declaration Syntax
class Classname
{
var_datatype variablename;
:
met_datatype methodname(parameter_list)
:
}

Sample class

Nested Classes
Defining one class within another is called
‘Nesting’
Types:
 Static
 Non-static

Data Types
 byte
 char
 boolean
 short
 int
 long
 float
 double
 Array
 Class
 Interface

Type Casting
 One data type is converted into another data
type
 Example
float c = 34.89675f;
int b = (int)c + 10;

Variables
 Three components of a variable declaration:
 Data type
 Name
 Initial value to be assigned (optional)
 Syntax
datatype identifier [=value][, identifier[=value]...];

Java Reserve words

Array Declarations
 Three ways for Array Declaration:
 datatype identifier [ ];
 datatype identifier [ ] = new datatype[size];
 datatype identifier [ ]= {value1,value2,….valueN};

Methods in Classes
 A method is defined as the actual
implementation of an operation on an object
 Syntax
access_specifier modifier datatype method_name(parameter_list)
{
//body of method
}

Sample usage of Method

Access specifiers for Methods

Method Modifiers
 static
 abstract
 final
 native
 synchronized
 volatile

Methods Overloading
 Overloaded Methods:
 Are in the same class
 Have the same name
 Have different parameter lists
 Overloaded methods are a form of compile
time polymorphism

Methods Overriding
 Overridden Methods:
 Are in the superclass as well as the subclass
 Are redefined in the subclass
 Overridden methods are a form of runtime
polymorphism

Class Constructors
 Special method used to initialize member
variables of the class
 Same name as the Class name and does
not have a return type
 Called when an object is created
 Types:
 Explicit constructors
 Implicit constructors

Derived class constructors
 Has the same name as the subclass
 Statement that calls the constructor of the
superclass should be the first statement in
the constructor of a subclass

Operators
Java Provides following categories of Operators:
 Arithmetic Operators
 Bitwise Operators
 Relational Operators
 Logical Operators
 Conditional Operators
 Assignment Operators

Operator Precedence

Escape Sequence

Control Flow
 Decision – making
 if-else statement
 Switch-else statement
 Loops
 while loop
 do-while loop
 for loop

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Learn Java language fundamentals with Unit nexus

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