2. JAVA VariablesOperators

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Variables and Operators

Like C.


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Module Introduction

1. Introduction to Variables Explain variables and their purpose.

Rule and naming variablesconventions

2. Introduction to Data Types Identify the different data type and

explain their purpose

Primitive and reference data types

3. Formatted Output and Input

4. Operators

5. Type casting

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#1 Variables

A location in the computers memory where a value is stored

and from which the value is retrieved later.

Variables must be declared before they can be used.

Syntax:

datatype variableName;

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Naming variables Conventions

May consist of Unicode letters and digits, _, $

Always begin your variable names with a letter.

Must not be a keyword or reserved word in Java.

Variable names in Java are case-sensitive

If a variable name comprises a single word, the name should be inlowercase (for example, velocity or ratio).

If the variable name consists of more than one word, the first letterof each subsequent word should be capitalized

employeeNumber, accountBalance

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#2 - Data Type

Determines the type of data that canbe stored in the variable

Determines the operations that can be

performed on this data.

Two categories of Java data type:

1. Primitive data types

2. Reference data types

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Primitives data types

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Reference data types

A variable of a reference data type holds the reference to theactual value or set of value represented by the variable.

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#3 - Format Specifier

To format output displayed on the screen.

Use: printf(String format, Object... args)

format(String format, Object... args)

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Example of Format Specifiers

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Formatted input

Using the Scanner object in java.util package

Example

Scanner input = new Scanner(System.in);

int i = input.nextInt();

long l = input.nextLong();

float f = input.nextFloat();

double d = input.nextDouble();String s = input.nextLine();

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Escape Sequences

Special sequence of character that is used to representcharacters which cannot be entered directly into a string.

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#4 Operator

Mechanism for performing various operations on the datastored in variables.

Z = A + B

Z = A + B call an Expression Z, A, B called operands

=, + called operator

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Assignment Operator (=)

Assign the value on its right to theoperand on its left.

Allow to create a chain of assignment

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Arithmetic Operator

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Unary Operator

++, -- : can be applied before(prefix) or after (postfix) the operand

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Relational Operators

Test the relationship between two operands.

Always evaluates to a boolean value (true or false)

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Conditional Operators

&&, || : work on two boolean operand.

? : : conditional operator accepts three operands

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Bitwise and Bit shift Operators

Work on binary representation of data.

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Operator Precedence

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Operator associativity

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#5 - Type Casting

One data type converts into anotherdata type

Two type of casting

1. Implicit casting2. Explicit casting

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Implicit Type Casting

Automatic type conversion

Conditions

Two type should be compatible

The destination type should be larger than thesource

The primitive numeric data type can beimplicitly cast (type promotion rule)

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Explicit Type Casting

To convert a higher precision data type tolower precision data type such as float to int.

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Thats about all for today!

Variables

Operators

Type Casting Implicit casting

Explicit casting

Thank you al l for yo ur attent ion and pat ient !

2. JAVA VariablesOperators

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