Coding Fun Java Selenium Tutorial For Beginners 9|Java Variables and Operators|G C Reddy|

Selenium Tutorial For Beginners 9|Java Variables and Operators|G C Reddy|





Java Tutorial for Beginners, Java Language Elements, Variables and Operators in Java Programming, What is Variable?, Declaration of variables in Java, Assign Values to Variables, Variable Naming Rules in Java, and Types Variables.
Java Local Variables, Instance Variables, and Class/Static Variables.
Java Arithmetic, Assignment, Comparison or Relational, and Logical Operators.

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2 thoughts on “Selenium Tutorial For Beginners 9|Java Variables and Operators|G C Reddy|”

  1. G C Reddy says:

    Class Notes:
    Selenium Class 9: Java Variables, and Operators
    ————————————————
    i) Java Variables
    ii) Java Operators
    ————————————————
    i) Java Variables
    ————————————————
    1) What is Variable?

    A named memory location to store the temporary data within a program,

    Two types of memory in Computer Environment
    a) Primary Memory (RAM)
    b) Secondary Memory (ROM- CD, DVD, HDD, USB etc…)
    ———————————-
    2) Declaration of Variables

    Java supports Explicit Declaration of Variables,

    In Java;

    dataType VariableName;
    dataType Variable1Name, Variable2Name, Variable3Name;
    dataType variableName= value;
    dataType Variable1Name=value, Variable2Name=value, Variable3Name=value;

    Example:
    int a;
    char b;
    boolean c;
    double d;
    String e;
    a=10;
    b='X';
    c= false;
    d= 12.345;
    e="Selenium Testing";

    int f, g, h;
    f=50; g=60; h=70;

    int i=100;

    int j=12, k=13, l=14;
    ———————————————
    3) Assign values to Variables

    Two types of Assign values to Variables
    a) Initialization
    int a =100;
    or
    int b;
    b=200;
    b) Reading
    Read Input (Using Input Devices)
    Read from Files (Text/Excel/Database file…)
    *Read from Application Objects
    ———————————————————————
    4) Variable naming Restrictions

    a) Variables are case sensitive

    in Java
    int a;
    int B;
    a=100;
    B=200;
    System.out.println(A); //Incorrect
    System.out.println(a); //Correct
    System.out.println(B); //Correct
    System.out.println(b); //Incorrect
    ————————————–
    Dim a
    .
    .
    A=100
    .
    .
    Msgbox a'100 (Correct Syntax)
    ——————————————————————-
    b) Java Variable names should start with a letter or $ or _

    Ex:
    myvar
    MYVAR
    $myvar
    _myvar
    7myvar //Incorrect
    *myvar //Incorrect
    myvar7
    ————————————
    c) Variable names should not match with Java Keywords and Reserved words

    if, for, import, while, new…..(Keywords)
    true, false…..(Reserved Words)

    int a;//Correct
    int for; //Incorrect
    ————————————————————–
    d) Must be unique in the scope of declaration (No duplicate variables in a program)
    —————————————-
    e) Must not exceed 255 characters
    ——————————————
    Three types of variables in Java,

    a) Local Variables
    Local Variables are declared in methods, or blocks.

    b) Instance Variables
    Instance Variables are declared in a class but outside of a method or any block.
    Instance variables are used by Objects to store their states.

    c) Class / Static Variables
    Static Variables are declared as static, these can’t be local
    ————————————————————————–
    If you declare Instance variable before main method then it can be used before
    main method only.

    If you declare Instance variable after main method then it can be used after main
    method only.

    Example:
    public class VariablesOperators {
    static int a =10;

    public int salary(){
    int mySalary = 10000 +2000+1500;
    mySalary = mySalary +a;
    return mySalary;
    }
    public static void main(String[] args) {
    //Static / Class Variable
    int b=20; //Instance variable
    System.out.println(b);//20
    VariablesOperators obj= new VariablesOperators();
    int e = obj.salary();
    System.out.println(e);//13510

    if (b>a){
    int x=123;
    System.out.println(a);//10
    System.out.println(b);//20
    System.out.println(x);//123
    }
    System.out.println(a);//10
    System.out.println(b);//20
    //System.out.println(x);//123//Error
    }
    }
    ————————————————————————–
    //Calling methods
    obj.salary();
    obj – Object
    salary – Method
    ———————————————————
    ii) Java Operators
    ———————————————————
    Operators are used to perform Arithmetic, Comparison, and Logical Operations,

    Categories of Java Operators,

    a) Arithmetic Operators

    b) Assignment Operators

    c) Comparison Operators

    d) Logical Operators
    ——————————————-
    a) Arithmetic Operators

    Arithmetic Operations,

    Addition, Subtraction, Multiplication, Division, Modules, Exponentiation etc…

    How to conduct Exponentiation in Java? -Jyothi
    —————————————————-
    1) Addition + (Addition, String Concatenation)
    int a=10, b=20;
    int c = a+b; //Addition
    ————–
    String d = "Selenium";
    String e = " Testing";
    String f = d+e; //"selenium Testing"
    ——————————————–
    2) Subtraction – (Subtraction, Negation)

    int a=20, b=10;
    int c = a-b;//10 (Subtraction)

    int d = -100;//negation
    ————————————————-
    3) Multiplication *

    4) Division /

    5) Modules %

    6) Increment ++

    7) Decrement —
    —————————————————–
    Example:

    public class VariablesOperators {
    public static void main(String[] args) {
    int a=10, b=5;
    String c= "Selenium", d= "Testing";

    System.out.println("Addion of a, b is: " + (a+b));//Addition of a, b is: 15
    System.out.println(a+b);//15
    System.out.println(c+d);//SeleniumTesting
    System.out.println(a-b);//5
    System.out.println(a*b);//50
    System.out.println(a/b);//2
    System.out.println(a%b);//0

    b=10;
    a = ++b;
    System.out.println(a);//11

    b=10;
    a = –b;
    System.out.println(a);//9

    }
    }
    ——————————————————
    b) Assignment Operators

    1) Assignment =

    2) Add and Assign +=

    3) Subtract and Assign -=

    4) Multiply and Assign *=
    ——————————————–
    Example:

    public class VariablesOperators {
    public static void main(String[] args) {
    int a=10;

    System.out.println(a);//10
    a= a+10;
    System.out.println(a);//20

    a=10;
    a += 10;
    System.out.println(a);//20

    a -=10;
    System.out.println(a);//10

    a *= 10;
    System.out.println(a);//100
    }
    }
    ————————————————————–
    c) Relational / Comparison Operators
    ————————————————
    1) ==

    2) !=

    3) >

    4) >=

    5) <

    6) <=
    ————————————————
    Note: Relational Operators return Boolean / Logical (true/false) Result
    ———————————
    Example:
    public class VariablesOperators {
    public static void main(String[] args) {
    int a=10, b=20;

    System.out.println(a>b);//false
    System.out.println(a>=b);//false

    System.out.println(a<b);//true
    System.out.println(a<=b);//true

    System.out.println(a==b);//false
    System.out.println(a!=b);//true
    }
    }
    ————————————————

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