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 |