string_handling

String handling in java:-
A string is a data type used to represent text. It is a set of characters enclosed within double quotes. In java String is a class. There are many functions in this class to provide features that helps in string handling.
Here is the list of all functions with their return type, arguments and the functionalities.

Function name Arguments Return type Functionality Example
trim() String It removes the leading and trailing spaces , if any, from the string. It doesn’t remove the spaces  present in between the string. String str=”   Program   ”; String res=str.trim(); System.out.println(res); o/p Program
toLowerCase() String It converts each character in a string to lowercase. String str=”ComPuteR”; String res=str.toLowerCase(); System.out.println(res); o/p computer
toUpperCase() String It converts each character in a string to Uppercase. String str=”ComPuteR”; String res=str.toUpperCase(); System.out.println(res); o/p COMPUTER
length() int It returns the length of the string (The no. of characters in the string) String str=”Computer”; System.out.println(str.length()); o/p 8
charAt() int char It accepts an integer(index) and returns the character at that  particular index . The index of the string rages from 0 to length()-1 String str=”Computer”; System.out.println(str.charAt(0)); o/p C
indexOf() char int It takes a character and returns the index of the first occurrence of the specified character in a string. If the character is not present in the string it will return -1  String str=”Computer”; System.out.println (str.indexOf(‘C’)); o/p 0
indexOf() char int It takes a character and returns the index of the last occurrence of the specified character in a string. If the character is not present in the string it will return -1  String str=”Pineapple”; System.out.println (str.lastindexOf(‘p’)); o/p 6
concat() String String It joins or concatenates two strings. String str1=”Computer ”; String str2=”Program ”; String str3=str1.concat(str2); System.out.println(str3); o/p Computer Program
equals() String boolean It checks whether two strings are equal or not. It returns a boolean, if the strings are same true otherwise false. String str1=”Computer ”; String str2=”Program ”; System.out.println(str1.equals(str2)); o/p false                          
equalsIgnoreCase() String boolean It checks whether two strings are equal or not after ignoring their case. It returns a boolean, if the strings are same true otherwise false. String str1=”Computer ”; String str2=”computer ”; System.out.println(str1.equalsIgnoreCase(str2)); o/p true                           
CompareTo() String int This method compares two strings. It not only checks the equality of the strings but also checks whether a string is bigger or smaller than the other string.  It returns an integer, if str1==str2   it returns  zero. if str1>str2   it returns  positive integer if str1==str2   it returns  negative integer.   String str1=”CAT ”; String str2=”FOX ”; System.out.println(str1.comparerTo(str2)); o/p -3 * When we compare “CAT” and “FOX” , the first occurrence where these two string differ is ‘C’ and ‘F’. The result is -3(67-70), which is the difference of their equivalent ACCII value           
CompareToIgnore() String int This method compares two strings ignoring their case . It not only checks the equality of the strings but also checks whether a string is bigger or smaller than the other string.  It returns an integer, if str1==str2   it returns  zero. if str1>str2   it returns  positive integer if str1==str2   it returns  negative integer.   String str1=”CAT ”; String str2=”cat ”; System.out.println(str1.comparerToIgnore(str2)); o/p 0                                  
replace() Two char String It replaces all occurrences of a character in a string with another character. String str1=”jack and jill ”; System.out.println(str1.replace(‘j’,’z’)); o/p zack and zill             
subString() int String It returns a new string that is a substring of the given string String str1=”jack and jill ”; System.out.println(str1.subString(9)); o/p zill *It extracts the string form index 9 to the end of the string ____________________ String str1=”jack and jill ”; System.out.println(str1.subString(5,8)); o/p and *It extracts the string form index 5 to 7
startsWith() String Boolean It checks whether a string starts with a particular string. String str1=”jack and jill ”; String str2=”jack”; System.out.println(str1.startsWith(str2)); o/p true                           
endsWith() String Boolean It checks whether a string ends with a particular string. String str1=”jack and jill ”; String str2=”jack”; System.out.println(str1.endssWith(str2)); o/p false                          
valueOf() Any primitive datatype String It returns the string representation of the argument. int num1=123; System.out.println(String.valueOf(num1)); o/p 123 *In string datatype 

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