Selenium Automation Testing using Java: Important String class Methods

Important String class Methods:

class String

{

int Length()

{

}

toUpperCase()

{

}

toLoerCase()

{

}

package StringBasicNew1;

public class LengthOfString {

public static void main(String[] args) {

// Declare String variable and store "RaMa" val

String s = "RaMa";

// length of string

int l = s.length();

// 4

// l= 4

// return / gives length of String i.e how many characters are there in String i.e 4 // value will be stored in left side variable i.e l

// so l contains 4 value

// display length

System.out.println("Length of string="+ l);

// s = "Ram" ; length= 3 ?

s= "Ram";

l = s.length();

// 3

// l = 3

System.out.println("Length of string="+ l);

// HW s= "sita" , length =?

// HW s= "Rama rao";// 8 count space char also

//String toUppercase():

// convert the given String to Upper case and return String value

// "RaMa" --> "RAMA"

// "RAMA" --> "RAMA"

s= "RaMa";

String ucaseString = s.toUpperCase();

// "RaMa". --> "RAMA"

// "RAMA"

// ucaseString = "RAMA"

System.out.println("ucaseString="+ucaseString);

// RAMA

// HW s = "sita" convert into upper case?

// s.toLowerCase() "RaMa" // covert the given String to lower case

s= "RaMa";

String lcaseString = s.toLowerCase();

// RaMa

// rama

// lcaseString = rama

System.out.println("lcaseString ="+ lcaseString);

//HW s = "SitA" --> convert string to lower case -->

// sita

// HW s= Rama rao , convert string to lower case -->

// rama rao

}

HW:

// Declare String var

String s ;

s= "RaMa rao";

// 1234

//HW length of string

// HW convert to upper case and lower case?

o/p:

charAt(int indexno) :

char charAt(int indexno)

{

}

· The charAt method is a predefined method in the Java language

· It can be used to get the character value at a given index (0, 1, 2, etc.).

· It returns the character value at the specified index.

· The return type is char.

package StringBasicNew1;

public class CharAtBasics {

public static void main(String[] args) {

String s = "RAM"; // length = 3

// 012 34567 index numbers

// get char at index no =0 i.e 'R'

char ch0 = s.charAt(0);

// 'R'

// ch0 = 'R'

System.out.println("ch0="+ ch0);

// 'R'

// get char at index no =1 i.e 'A'

char ch1 = s.charAt(1);

// 'A'

// ch1= 'A'

System.out.println("ch1="+ ch1);

// 'A'

// HW get char at index no =2 i.e 'M'

// get char at index no =4 ????

// char ch4 =s.charAt(4);// Error// Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 3

// as we are using invalid index no i.e index no =4 is not valid

// display char

// System.out.println("ch4="+ ch4);

// get each Char from String and display using for loop

// RAM

// 012

System.out.println("***************");

s = "RAMA rao";

// 01234567 -- l = 8

// for(int i=0;i<=2;i++)

for(int i=0;i<=s.length()-1;i++)

{ // i<=7

char ch =s.charAt(i);

// s.charAt(1);

//.....

System.out.println("ch="+ch);

}

System.out.println("after for loop");

// ch=R

// ch=A

// ch=M

}

Note1:

· Nested if statements - possible

· Nested for loops - possible

· Nested methods - not possible

Example demonstrating that nested methods are not allowed:

package StringBasicNew1;

public class TestNestedMethod {

// Define M2 inside M1()

public static void M1()

{

public static void M2() // Nested Method is not possible

{ // We cannot define method inside another method

}

public static void main(String[] args) {

}

2. Duplicate methods with the same data type arguments are not allowed in Java.

· The same method signature is not allowed.

Duplicate method with same data type args not allowed in java

Same method signature is not allowed .

Method signature --> Method name + parameter list

public static void main(String[] arr) { // always execution start from main () which has signature public static void and Main() we have to pass String array...

}

package StringBasicNew1;

public class TestNestedMethod {

// public static void main(String[] args) { // error

// }

public static void main(int[] args) {

}

public static void main(int a) {

}

// public static void main(int x) // erro e

// {

// }

public static void main(String[] args) {

}

int indexOf(String s):

The indexOf method returns the index within this string of the first occurrence of the specified substring.

If the substring is not found, it returns -1.

String s = "RAMA";

// 0123

get index no of given String i.e R --> 0

if given string is not there in main String , it returns -1.

return type - int

package StringBasicNew1;

public class indexOfBasics1 {

public static void main(String[] args) {

String s = "RAMA";

// 0123

//get index no of given String i.e R

int indexOfR = s.indexOf("R");

// 0

// can be used to get index no of given String val i.e "R" - 0

// indexNoOfR = 0

System.out.println("indexOfR="+indexOfR);

// 0

// index no of given value "A"

int indexOfA = s.indexOf("A");

// can be used to get index no of given String val 'A' i.e 1

// indexOfA = 1

System.out.println("indexOfA="+indexOfA);

// 1

//HW get index no of given String val "M" i.e 2

// -ve if given String val is not there i.e "P" in main string, this method return -1

int indexOfP = s.indexOf("P");

// -1

// indexOfP = -1

System.out.println("indexOfP="+indexOfP);

// -1

// Note : if duplicates characters are there in String i.e "A ", it always gets the first matched index no

int indexOfA1 = s.indexOf("A");

// 1

// indexOfA1 == 1 but not 3

System.out.println("indexOfA1 ="+indexOfA1);

// 1

}

// String substr(int indexno) :

The substring method can be used to get a subpart or some part of the string from the given index to the last index.

String s = "RAMA";

// 0123

String s0 = s.substring(0);

// // Get string values from index 0 to the end

package StringBasicNew1;

public class SubStringWith1Arg {

public static void main(String[] args) {

// substr() : can be used to get sub part or some part of string from given index no to till last index no

String s = "RAMA";

// 0123

// substr(int index) : can be used to get sub part or some part of string from given index no to till last index no

// get string values from index no 0 to all

String substring0 = s.substring(0);

// get string values from index no 0 to all

// RAMA

// substring0 = RAMA

System.out.println("substring0="+substring0);

// // get string values from index no = 1 to all

String substring1 =s.substring(1);

// substring1= AMA

System.out.println("substring1="+substring1);

//HW get string values from index no = 2 to all

// HW get string values from index no = 3 to all

// get string values from index no = 4 to all

String s4= s.substring(4);

System.out.println("s4="+ s4);

// Note : it does not throw error, even if we use invaid idex no

// it displays empty value subStr4=

}

Substring with 1 arg:

substring(int startIndexNo)

substring(int startIndexNo , int endingindexNo)

The substring method can be used to get a part of the string from the given start index to the end index (excluding the end index).

String s = "RAMA";

// 0123

// substring(0,n) --> get values from o to n-1 indexno

// substring(0,1) --> get values from o to 0 indexno i.e “R”

// substring(0,2) --> get values from o to 1 indexno i.e “RA”

// substring(0,3) --> get values from o to 2 indexno i.e “RAM”

package StringBasicNew1;

public class SubStringWith2Args {

public static void main(String[] args) {

String s = "RAMA";

// 0123

//get string values from index no =0 to 0 indexno i.e R

String s01 = s.substring(0, 1); //0,0

// s01= R get string values from index no =0 to n-1 indexno

System.out.println("s01="+ s01);

// get string values from index no =0 to 1 =

String s02=s.substring(0, 2);// get string values from index no =0 to 2-1 = 1

// RA

// s02 = RA

System.out.println("s02="+ s02);

//HW get all string values from 0 to 2 o/p: RAM

// HW get all String values from 0 to 3 o/p: RAMA

}

package StringBasicNew1;

public class SubStringWith2Args2 {

public static void main(String[] args) {

String s = "RAMA";

// 0123

// subString( beginindex, end index)

// 1,n - values from 1 to n-1 indexno

String s12=s.substring(1, 2);// get string values from indexno =1 to 2-1 i.e 1,1

// A

System.out.println("s12 ="+ s12);

String s13= s.substring(1, 3);

// get string values from index no =1 to 3-1 =2 1,2

// AM

System.out.println("s13="+s13);

String s11= s.substring(1, 1);// get string values from indexno =1 to 1-1 = 0

// empty val ***

System.out.println("s11 = "+ s11);

}

o/p:

HW Write o/p for below program String s = "RAMA Rao"; display ?

s.substring(2, 3);

s.substring(2, 4);

s.substring(2, 5);

HW Write o/p for below program String s = "RAMA Rao"; display ?

s.substring(3, 6);

s.substring(3, 5);

s.substring(3, 4);

LastIndexOf():

The lastIndexOf method returns the index within this string of the last occurrence of the specified substring.

If the substring is not found, it returns -1.

gets last index no of given string

String s = "rama";

// 0123

// s.indexOf("a");

s.lastIndexOf("a");

package StringBasicNew1;

public class LastIndexOf {

public static void main(String[] args) {

String s = "rama";

// 0123

// s.indexOf("a"); //

// returns /gives index no go given String "a" -- first matched index no = 1

// get last index no of given String 'a'

int lastIndexOfa = s.lastIndexOf("a");

// 3

// lastIndexOfa = 3

// Last index no of given String value 'a' =3

System.out.println("lastIndexOfa="+lastIndexOfa);

// 3

}

s= "CNo: '123' is created succcesfully"

Get number from 123 which is enclosed in ''

package StringBasicNew1;

public class GetNumberFromStringinSingleQuotes {

public static void main(String[] args) {

//// s= "CNo: '123' is created succcesfully"

// s= "CNo: '25065' is created succcesfully"

// get numbers in single quotes ''

// o/p: 123

// 25065

String s="CNo:'123' is created succcesfully";

// 0123456789

// String s="CNo:'25065' is created succcesfully";

// 012345678910

// get numbers from single quotes

// String number = s.substring(5, 8);

// get values from index no =5 to 7

// "123"

// System.out.println("number="+number);

// get indexno of first single quotes

int firstIndexOfQuotes = s.indexOf("'");

// 4

// get index no of last single quotes '

int lastIndexofQuotes = s.lastIndexOf("'");

// 8

String number = s.substring(firstIndexOfQuotes + 1, lastIndexofQuotes);

// 5,8 -- valeus from index no =5 to 7

System.out.println("number="+number);

// number=123

}

HW get 182 from string s= "Inbox (182)";

s= "Inbox (2000)";

o/p : 182

Hw get 123 from String "order: 123 created"

o/p: 123

Note:

// == Relational operator ==,<,><=, >=, !=

// == operator can be used to compare the numbers but not string values

// ex: 10 == 10 -->

10 == 30 -->

// If We want to compare 2 String values- we have to use Equals().

Don't use == to compare string values or content

// Equals() method - can be used to check 2 given String Values are equal or not

// if 2 string values are equal - this method returns true

// else false

package StringBasicNew1;

public class Equals {

public static void main(String[] args) {

String s1 = "Ram";

String s2= "Ram";

String s3 ="sita";

// check s1 equals s2

boolean s1s2Result = s1.equals(s2);

// "Ram".equals("Ram");

// true

//s1s2Result = true

System.out.println("s1s2Result="+s1s2Result);

// true

// check s1 equals s3

boolean s1s3result = s1.equals(s3);

// "Ram".equals("sita")

// false

//s1s3result = false

System.out.println("s1s3result="+s1s3result);

// false

}

concat():

+ --> addition operator

+ --> concatenation operator -- join values if any one value is String

It can be used to join 2 string values, concatenation operations

package StringBasicNew1;

public class ConcatenationBasics {

public static void main(String[] args) {

String s1 = "Ram";

String s2= "Ram";

String s3 ="sita";

// join s1 and s3 "Ram" "Sita" --> "RamSita"

String s1s3Concat = s1.concat(s3);

// "Ram" "Sita"

// "RamSita"

System.out.println("s1s3Concat="+s1s3Concat);

// HW join s1 and s2

// res

}

Note:

System.out.println("s5="+s5);// s5=ramsitaLakshman

// s3.concat(10);// error :

//The method concat(String) in the type String is not applicable for the arguments (int)

We must pass String value in concat(Sting) but not int no

s1.contains(String s2):

The contains method can be used to check if a string (s1) contains another string (s2).

If s1 contains s2, this method returns true.
Otherwise, it returns false.

package StringBasicNew1;

public class containsBasics {

public static void main(String[] args) {

String s1 = "ramsitaLakshman";

String s2 = "ram";

// check s1 contain s2 value -- true else false

boolean s1containss2 = s1.contains(s2);

// ramsitaLakshman ram

// true

// s1containss2= true

System.out.println("s1containss2="+s1containss2);

// true

// check s1 contains "Hanuman"

boolean res2 =s1.contains("Hanuman");

// ramsitaLakshman Hanuman

// false

/// res2 = false

System.out.println("res2="+ res2);

// false

}

String trim():

The trim method can be used to remove leading and trailing spaces from a string.

It can be used to remove spaces in String from both sides

" Ram sita "

package StringBasicNew1;

public class TrimBasics {

public static void main(String[] args) {

// Trim() - used to remove spaces in String from both sides

String s1 = " ram sita Lakshman ";

System.out.println("before Trim -s1="+ s1);// ram sita Lakshman

// remove spaces in String from both sides

s1 = s1.trim();

// "ram sita Lakshman" -- no spaces

System.out.println("after trim s1="+s1);

}

o/p:

before Trim -s1= ram sita Lakshman

after trim s1=ram sita Lakshman

char[] toCharArray():

The toCharArray method converts a string to a character array.

Return type: char[]

package StringBasicNew1;

public class TocharArrayBasics {

public static void main(String[] args) {

// ToCharArray

String s = "ram";

// convert string to char array

char [] charr = s.toCharArray();

// ram

// 012

// char chArr = s.toCharArray();

// Type mismatch: cannot convert from char[] to char

// left side, we must declare char array using [] but not char variable

// get values from char array by index no =0,1

System.out.println("charr[0]="+ charr[0]);

// r

System.out.println("charr[1]="+ charr[1]);

// a

//HW get all values from char array using for loop with int indexno

// Hw get all values from char array using 'foreach' loop

}

boolean startsWith(String s2):

The startsWith method can be used to check if a string (s1) starts with a given value.

If s1 starts with the specified s2 value, this method returns true.
Otherwise, it returns false.

s1.startswith(s2):

String s1 = "Ram sita lakshman";

// check S1 startswith "Ram"

> true

can be used to check String s1 starts with given value- it returns true else false

check s1.startswith '';

boolean s1startsWithRam= s1.startsWith("Sita");

// --> false

package StringBasicNew1;

public class StratsWithEndsWith {

public static void main(String[] args) {

String s1 = "Ram sita lakshman";

// check s1 starts with "Ram"

boolean res =s1.startsWith("Ram");

// "Ram sita lakshman" "Ram"

// true

// res = true

System.out.println("res="+ res);

// true

// check s1 starts with "Sita"

res =s1.startsWith("Sita");

// // "Ram sita lakshman" "Sita"

// false

System.out.println("res="+ res);

// check s1 starts with "ram"

res =s1.startsWith("ram");

// "Ram sita lakshman" "ram"

// false

System.out.println("res="+ res);

}

//HW WAP to check String s1 = "Ram sita lakshman" endswith "laskhman"

check s1 ends with sita

check s1 ends with "Lakshman"

String Replace("old val", "new val"):

The replace method can be used to replace an old value with a new value in a string.

String s = "ram-sita-laskhman";

// replace - eifen --> by comma ,

--> String replacedString = s.replace("-", ","); // replacedString = "ram,sita,lakshman"

package StringBasicNew1;

public class ReplaceBasics {

public static void main(String[] args) {

//Replace

String s = "ram-sita-laskhman";

// replace - eifen --> by comma ,

String s1 = s.replace("-", ",");

// "ram-sita-laskhman"

// s1 ="ram,sita,laskhman";

System.out.println("s1="+ s1);

// in s1, replace comma , by spaces

// --> "ram sita laskhman";

s1= s1.replace(",", " ");

System.out.println("s1="+ s1);

// s1=ram sita laskhman

//HW . in String S , replace "ram" by "Amar"

// "ram-sita-laskhman";--> "Amar-sita-laskhman"

}

String[] Split("String val" or reg exp) :

The split method can be used to split a string into an array of substrings based on the given regular expression (regex). It stores all the values in a string array.

(or)

to split the values based on given String value i.e - , and it stores all values in String array

-return type is string array

String s = "10-20-30";

package StringBasicNew1;

public class SplitBasics {

public static void main(String[] args) {

String s = "10-20-30";

// split the values based on given String value i.e - , and it stores all values in String array

// return type - string [] array

// split by "-"

String [] sarr = s.split("-");

// "10-20-30"

// sarr[0] = 10

// sarr[1] = 20

// sarr[2] = 30

// display values

System.out.println("sarr[0]="+ sarr[0]);

//sArr[0]= 10

// sArr[1]=

System.out.println("sarr[1]="+ sarr[1]);

// 20

// HW display all values from sArr using for loop with index no

// HW display all values from sArr using 'for each' loop

}

HW Split the String with comma (,) and display array values

// String s1 = "11,22,33,44"

HW Split String by space and display array values

// String s3 = "Ram sita lakhman";

//HW get only 100.00 from "$ 100.00"

String s4 = "$ 100.00";

// 100.00

Hint : use replace or substring()?

// HW get 100.00 from "100.00 $" use Substring and index no

IP FAQ Swap 2 variables using 3rd variable ?

// a= 10 b=20

// o/p: a=20 , b=10

package StringBasicNew1;

public class Swap2NumbersUsing3rdVariable {

public static void main(String[] args)

{

int a =10;

int b=20;

System.out.println("Before swapping a="+ a + " b="+b);

int tmp;

tmp = a;

a = b;

b = tmp;

System.out.println("After swapping a="+ a + " b="+b);

}

IP: FAQ Swap 2 variables without 3rd variable ?

package StringBasicNew1;

public class Swap2NumberswihOutUsing3rdVariable {

public static void main(String[] args) {

int a = 3;

int b = 2;

System.out.println("Before swapping a="+ a + " b="+b);// 3 , 2

// not using any 3rd variable, use substraction and addition and

a = a - b;

// 3 -2

// 1

// a = 1 latest value

b = a + b;

// 1 + 2

// 3

// b = 3 Latst value

a = -(a - b);

// -(1 - 3)

// -(-2)

// a= +2

// a = 2

// note: we can write this stmt a = -a + b; (or) a = b-a;

// a = -a + b;

// (or)

// a = b-a;

System.out.println("After swapping a="+ a + " b="+b);

}

o/p:

Before swapping a=3 b=2

After swapping a=2 b=3

IP: FAQ "Ram is good boy"; Count of words in String ?

String s = "Ram is good boy";

o/p: 4

package StringBasicNew1;

public class CountofWordsFromString {

public static void main(String[] args) {

// FAQ "Ram is good boy";

// Count of words in String ? 4

String s= "Ram is good boy";

//String s= "Ram is good boy. Sita is from Srilanka.";

// split by space

String[] sarr = s.split(" ");

// sarr[0] = ram

// sarr[1] = is...etc

// count of array

int wordsCnt = sarr.length;

// 4

// count of words= 4

System.out.println("wordsCnt="+wordsCnt);

// display 1st,2nd word

System.out.println("1st word ="+ sarr[0]);

System.out.println("2nd word ="+ sarr[1]);

// display all values from array using with for loop with index no

for(int i=0;i<=sarr.length-1;i++)

{

System.out.println("all values fron string array =" + sarr[i]);

}

// display all values from array using 'for each' loop

for(String x : sarr)

{

System.out.println("all values from array using for each loop ="+ x);

}

o/p:

wordsCnt=4

1st word =Ram

2nd word =is

all values fron string array =Ram

all values fron string array =is

all values fron string array =good

all values fron string array =boy

all values from array using for each loop =Ram

all values from array using for each loop =is

all values from array using for each loop =good

all values from array using for each loop =boy

IP : FAQ VImp *** : Reverse of String ?

i/p: RAM

o/p: MAR

Sita

atiS

way1-: using charAt():

package StringBasicNew1;

public class ReverseOFStringUsingCharAt {

public static void main(String[] args) {

String s = "RAM"; // sl.length() ; //5

// 012

// o/p: MAR

//way1-: using charAt()

//--------------------------------

for(int i=2;i>=0;i--) // i varies 2 = to 0 // i =2, 2-1 =1, 1-1=0, 0-1 = -1

{ // 2>=0 true, enters for loop

// 1>=0 , true, enters for loop

// 0>=0 true , for

// -a>=0 false, ctrl goes after for loop

char ch = s.charAt(i);

// 2 - 'M'

// 1 - 'A'

// 0 -- 'R'

// ch = 'R'

System.out.print(ch);// MAR

}

// AMAR

}

Way2 using to chararay():

package StringBasicNew1;

public class ReverseOFStringUsingCharARRay {

public static void main(String[] args) {

String s = "RAM"; // sl.length() ; //5

// 01234

// o/p: MAR

char [] charr = s.toCharArray();

// "RAM" ---> R A M

// 0 1 2

for(int i=2;i>=0;i--)

{

System.out.print(charr[i]);

}

Way 3: always prefer this one

package StringBasicNew1;

public class ReverseOFStringUsingCharAt2 {

// Define method - reverseOfString and pass String var

public static String reverseOfString(String s)

{ // RAM s= RAM

// 012 len= 3

String rev = ""; // rev = ""--> "M" --> "MA" --> "MAR"

for(int i=s.length()-1;i>=0;i--)// i=2, 2-1=1, 1-1=0, 0-1 = -1

{ // i=3-1 =2;2>=0, true, for loop

// 1>=0 true , for loop

// 0>=0 , for loop

// -1>=0 false, after for loop

char ch = s.charAt(i);

// s.charat(0) -'R'

// ch = 'R'

// System.out.println(ch);

rev = rev + ch;

// "MA" + R

// rev = "MAR"

// System.out.println("revers of string ="+ rev);

}

System.out.println("revers of string ="+ rev);

// MAR

return rev;

// "MAR"

}

public static void main(String[] args) {

System.out.println("hi");

String s = "RAMA"; // sl.length() ; //5

// 01234

// o/p: MAR

// call reverseOfString() and display the o/p

String result= reverseOfString("RAM");

// "MAR"

// result = "MAR"

System.out.println("result="+result);

// MAR

}

Selenium Automation Testing using Java

Thursday, July 25, 2024

Important String class Methods

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