Selenium Tutorial 10: Strings and Arrays in Java

Strings and Arrays in Java tutorial explains String handling in Java, Creating Strings, String Concatenation, and String Comparison. Array declaration, types of Arrays, print Array, copy Array, Array methods and Advantages & Disadvantages of Arrays.

[ellankih]

Assignment task - Print multi-dimensional array values using nested for loop - solution:
int [] [] arr1 = {{1, 2, 3, 4, 5}, {6, 7, 8, 9, 10}}; //2D - array
for (i = 0; i < arr1.length; i++) {
for (j = 0; j< arr1[i].length; j++) {
//This prints 1 to 10
}
}

[vasudha]

sir, u have the best teaching skills..any one can understand your explanation

[gcreddy]

Class Notes:
Selenium Class 10: Strings and Arrays in Java

i) String Handling in Java

ii) Arrays in Java

i) String Handling in Java

a) What is String?

> String is a sequence of characters written double quotes.

Numbers

Integers - byte, short, int, long data types

Floating point values/decimal values- float, double data types

Character -char

Logical values

boolean

String -Object


> String may have Alphabets, Numbers and Special characters.

Example:






b) Create Strings

String myTool ="Selenium";//String Variable
String [] myTools ={"UFT", "Selenium", "LoadRunner", "RFT"}; //Array of Strings



for (String tool: myTools){
System.out.println(tool);
}

c) Operations on Strings

1) Concatenating Strings

String str1 = "Selenium ";
String str2 ="Testing";
System.out.println(str1 + str2);//Selenium Testing
System.out.println("Selenium" + (1 + 1));//Selenium2
System.out.println("Selenium" + 1 + 1);//Selenium11
System.out.println(1 + 1 + "Selenium");//2Selenium
System.out.println("1" + 1 + "Selenium");//11Selenium
System.out.println("Selenium" + " ");
System.out.println(" " + "Selenium");

String + String = Concatenation

String + Integer = Concatenation

Integer + Integer = Addition

2) String Comparison

In computer programming we have 2 types of comparison

i) 2-way Comparison (true/false)

ii) 3-way Comparison (0, > 0, < 0)

a) String comparison using (==) Relational Operator

It supports 2-way Comparison(true/false)

b) Sting comparison using equals() method

It supports 2-way Comparison(true/false)

c) Sting comparison using compareTo() method

It supports 3-way Comparison (0, >0, <0)

// A to Z (65 to 90)
// a to z (97 to 122)
// 0 to 9 (48 to 57)

Example:
String str1 = "selenium";
String str2 = "SELENIUM";
String str3 = "SELENIUM";
String str4 = "zselenium";

//String Comparison using == Operator
System.out.println(str1 == str2);//false
System.out.println(str2 == str3);//true

//String Comparison using equals() method



//String Comparison using compareTo() method
than 0

than 0

Result Criteria for 3-way comparison

if str1 = str2 then 0

if str1 > str2 then > 0

if str1 < str2 then < 0

ii) Arrays in Java

a) What is Java Array?

> Java Array is an Object that holds a fixed number of values of a single data type.

> The length of Array is established when the Array is created.

> Array length is fixed, index starts from zero to n-1.

b) Declaration of Arrays

1st Method

dataType arrayName []; //Creating Array

arrayName = new dataType[size]; //Define Size

arrayName[0]=value;//Assign value
arrayName[1]=value;
arrayName[2]=value;
.
.

example:
int a [];
a = new int[3];

a[0]=10;
a[1]=20;
a[2]=30;
System.out.println(a[0]);//10
System.out.println(a[1] + a[2]);//50

//Assign values to elements that more than the length of Array (Run-Time Error)
int a [];
a = new int[3];

a[0]=10;
a[1]=20;
a[2]=30;
a[3]=40;//Out of Range(Run-Time Error)
System.out.println(a[0]);//10
System.out.println(a[1] + a[2]);//50

//Assign values to some elements only (No Error)

int a [];
a = new int[3];

a[1]=20;
a[2]=30;
System.out.println(a[1] + a[2]);//50

//If we assign invalid values (data type) -Syntax Error

int a [];
a = new int[3];
a[0] =1.23; //Syntax Error
a[1]=20;
a[2]=30;
System.out.println(a[1] + a[2]);//50

2nd Method

dataType [] arrayName= new dataType[length]; //Declare Array with length

arrayName[index] = value; //Assign value

Example:

int [] abc = new int [4];
abc[0] =10;
System.out.println(abc[0]); //10

3rd Method (Declare Array and Assign values)

dataType [] arrayName = {value1, value2, value3}

Example:
int [] xyz = {10, 20, 30, 40};


Declaring different types of Arrays

Example:
char [] abc = {'A', 'B', 'Z'}; //Array of Characters
int [] xyz = {10, 20, 30, 40}; //Array of Integers
String [] a = {"UFT", "Selenium", "RFT"}; //Array of Strings
boolean [] b ={true, false, false, true}; //Array of Boolean values






c) Copy Values from one to another

int [] array1 = {1, 2, 3, 4, 5};
int array2 [] = array1;


for (int i =0; i < array2.length; i++){

}

d) Types of Arrays

Two types of Arrays

1) Single dimensional Array

2) Multi dimensional Array

Example:

int [] array1 = {1, 2, 3, 4, 5};//Single dimensional Array
int [] [] array2 = {{1, 3, 5, 7}, {2, 4, 6, 8}};// Multi dimensional Array





Assignment

Print Multi dimensional Array (2D Array) values using Nested for loop.

e) Advantages & Disadvantages of Arrays

Advantages:

Using Arrays we can optimize the code, data can be retrieved easily.

We can get required data using index position

Disadvantages

We can store fixed number of Elements only.

It doesn't change its size during execution.

[anonymousanoymous]

Thank you for the great series on Selenium and also for all notes.

[KrishnakishoreGunturu]

Good explanation, videos are very helpful to understand the concepts

[Peperastael]

Super understandable thank you from Venezuela, Bless

[rishijuvekar]

Very helpful videos. Can you also possibly share the notepad files that has all the notes.
greatly appreciate !

[SheetalSakhare]

Sir We can create array with different data type.
EX:
Object empdetails [] = new Object[2];
empdetails[0]="amit";
empdetails[1]=15;

[anjanmitra]

Solution to the Assignment--
package Package1;

public class MyFirstClass {
public static void main(String[]args){




int [][] myArray={{2, 4, 6, 8}, {1, 3, 5, 7, 9}};

for (int i=0;i<myArray.length;i++){

for (int j=0;j<myArray[i].length;j++){



}}}}

[mitanayak]

Nice video sir.But I've a doubt in the following [] array1 = {1, 2, 3, 4, 5};
int array2 [] = array1;


for (int i =0; i < array2.length; i++){

}
Why did u declare array2 here?kindly explain.

[kazizahan]

In 'copy from one array to another ' section, why i<array2.length? why it is not i<=array2.length?

[biswajitsatpathy]

For character it is not showing any error because of upcasting.