Strings

Introduction

---

• String is an object that represents sequence of character values(alphabets,numbers,special characterises)


• Strings are immutable(i.e,unchangeable)


• They are always written in double quotes

Intialization :

Explicit

String s="Hello";String str="Hello_world123"

//s and str are names of the strings

Implicit

Scanner sc=new Scanner(System.in);
String s=sc.next();String str=sc.nextLine();

// next takes only a word as an input while nextline takes a sentence

String Functions

---

Method	Description
length()	Returns length of the string
charAt()	Returns the char value for a particular index
trim()	Removes beginning and ending spaces of a string
toLowerCase()	Returns string in lowercase
toUpperCase()	Returns the string in uppercase
indexOf()	Returns the first occurrence of the char value's index
lastIndexOf()	Returns the last occurrence of the char value's index
concat()	Attaches one string to another
equals()	Checks whether two strings are equal or not and returns a boolean value
equalsIgnoreCase()	Compare two strings to find if they are equal,ignoring case difference
compareTo(String)	Compare two string wheter they are equal or not and returns difference in ASCII value
compareToIgnoreCase(String)	Compare two string wheter they are equal or not,ignoring case difference
replace(old char,new char)	Searches a string for a specified value
substring(int,int)	Returns a new string which is substring of a specified string
startsWith(String)	Check whether a string starts with a specified character
endsWith(String)	Check whether a string ends with a specified character
valueOf()	returns the string representation of the specified value

length()

This method is used to return the length of the string
Return Type:int
Example:

Back to table

charAt(int)

This method returns the char value for a particular index
Return Type:char
Argument Type:int
Example:

Back to table

trim()

This method is used to remove beginning and ending spaces of a string
Return Type:String
Example:

Back to table

toLowerCase()

This method returns the string in lowercase
Return Type:String
Example:

Back to table

toUpperCase()

This method returns the string in uppercase
Return Type:String
Example:

Back to table

indexOf()

This method returns the first occurrence of the char value's index
Return Type:int
Argument Type:char
Example:

Back to table

lastIndexOf()

This method returns the last occurrence of the char value's index
Return Type:int
Argument Type:char
Example:

Back to table

concat()

This method is used to attach one string to another string
Return Type:String
Argument Type:String
Example:

Back to table

equals(String)

This method compares two strings and returns true of equal and false of not
Return Type:boolean
Argument Type:String
Example:

Back to table

equalsIgnoreCase(String)

This method compares two strings to find if they are equal or not,ignoring case difference
Return Type:boolean
Argument Type:String
Example:

Back to table

compareTo(String)

This method compares two strings and returns the difference of ASCII values if different and 0 if equal
Return Type:int
argument Type:String
Example:

Back to table

compareToIgnoreCase(String)

This method works same as compareTo function but ignoring case different
Return Type:int
argument Type:String
Example:

Back to table

replace(old char,new char)

searches a string for a specified value,and returns a new string where the specified values are replaced

Return Type:String
argument Type:char
Example:

Back to table

substring()

return a new string which is substring of a specified string
Return Type:String
Argument Type:int
Example:

Back to table

startsWith()

This method checks whether a specified string starts with specified character or not
Return Type:boolean
Argument Type:String
Example:

Back to table

endsWith()

This method checks whether a specified string ends with specified character or not
Return Type:boolean
Argument Type:String
Example:

Back to table

valueOf(all types)

This method returns the string representation of the specified value
Example:

Back to table