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 |
