A string is a sequence of characters that behave as an object in Java. The string is one of the very common and used data structures after arrays. It’s an object that stores the data in a character array.<\/p>\n\n\n\n
To elaborate, just consider a string as a character array wherein you can solve many string-based problems.<\/p>\n\n\n\n
To make a string object, you need the java language, String class. Java programming uses UTF -16 to show a string. Strings are immutable therefore their internal state remains constant after the object is entirely made. The string object performs many operations, but the string reverse in Java is the most widely used function.<\/p>\n\n\n\n
For this, various methods are used such as manual, inbuilt functions, and some useful classes that operate on the String objects.<\/p>\n\n\n\n
Example of String Reverse Program in Java<\/p>\n\n\n\n
For eg. HELLO string reverse and give the output as OLLEH<\/p>\n\n\n\n
Since the strings are immutable objects, you need to make another string to reverse them. The string class doesn’t have a reverse method to reverse the string. It has a to CharArray() method to do the reverse.<\/p>\n\n\n\n
Here below are some ways to reverse a string as follows;<\/p>\n\n\n\n
By Using toCharArray()<\/strong><\/p>\n\n\n\n The code given below would help to understand how to reverse a string. The toCharArray() method is an approach to reverse a string in Java.<\/p>\n\n\n\n The code also uses the length, which provides the total length of the string variable.<\/p>\n\n\n\n The for loop iterates until the end of the string index is zero.<\/p>\n\n\n\n Code<\/p>\n\n\n\n By using the Static method<\/strong><\/p>\n\n\n\n This method consists of the logic to reverse the string.<\/p>\n\n\n\n Make the object for the class Reverse of a String and call the static method with the object as rev. reverse(str)) bypassing the given string.<\/p>\n\n\n\n A method is also called recursive. In this program reverse(String s) is completely recursive.<\/p>\n\n\n\n Make the object for the class ReverseofaString rev. Read the string entered using sc.nextLine() and save it in the string variable str. Call the reverse method as rev. reverse(str).<\/p>\n\n\n\n Here i=length of the given string. The loop iterates until the condition i>0 is false, which means if the length of the string is zero then the cursor terminates the loop.<\/p>\n\n\n\n The loop prints the character of the string which is at the index (i-1) until i>0. Then we would get the reverse of a string.<\/p>\n\n\n\n For loop iterates from j=length of the string to j>0.<\/p>\n\n\n\n It prints the character of the string that is at the index (i-1), then we will get the reverse of a string.<\/p>\n\n\n\n Using StringBuilder.reverse() method to reverse a Java string efficiently. Also, it can also use the StringBuffer.reverse() method. To use StringBuilder is preferred as it\u2019s not synchronized and faster than StringBuffer.<\/p>\n\n\n\n Read Also<\/strong><\/p>\n\n\n\n\/\/ReverseString using CharacterArray.\r\n\r\npublic static void main(String[] arg) {\r\n\r\n\/\/ declaring variable\r\n\r\nString stringinput = \"Independent\";\r\n\r\n \/\/ convert String to character array\r\n\r\n \/\/ by using toCharArray\r\n\r\n char[] resultarray = stringinput.toCharArray();\r\n\r\n \/\/iteration\r\n\r\n for (int i = resultarray.length - 1; i >= 0; i--)\r\n\r\n \/\/ print reversed String\r\n\r\n System.out.print(resultarray[i]);}\r<\/code><\/pre>\n\n\n\nimport java.util.Scanner;\r\nclass ReverseofaString\r\n{public static void main(String[] arg)\r\n{ReverseofaString rev=new ReverseofaString();\r\nScanner sc=new Scanner(System.in);\r\nSystem.out.print(\"Enter a string : \");\r\nString str=sc.nextLine();\t\r\nSystem.out.println(\"Reverse of a String is : \"+rev.reverse(str));}\r\nstatic String reverse(String s)\r\n{String rev=\"\";for(int j=s.length();j>0;--j)\r\n\t{\r\n\trev=rev+(s.charAt(j-1)); \r\n\t}\r\n\treturn rev;\r\n\t}\r\n}\r<\/code><\/pre>\n\n\n\nUsing Recursion<\/h2>\n\n\n\n
import java.util.Scanner;\r\nclass ReverseofaString\r\n{\r\n\tString reverse(String s)\r\n\t{\r\n\t if(s.length() == 0)\r\n \t return \" \";\r\n \t return s.charAt(s.length()-1) + reverse(s.substring(0,s.length()-1));\r\n\t}\r\n\tpublic static void main(String[ ] arg)\r\n\t{\r\n\tReverseofaString rev=new ReverseofaString();\r\n\tScanner sc=new Scanner(System.in);\r\n\tSystem.out.print(\"Enter a string : \");\r\n\tString str=sc.nextLine();\t\r\n\tSystem.out.println(\"Reverse of a String :\"+rev.reverse(str));\r\n\t}\t\r\n}\r<\/code><\/pre>\n\n\n\nUsing While Loop<\/h2>\n\n\n\n
import java.util.Scanner;\r\nclass Reverse\r\n{\r\n\tpublic static void main(String[ ] arg)\r\n\t{\r\n\tString str;\r\n\tScanner scan=new Scanner(System.in);\r\n\tSystem.out.print(\"Enter a string : \");\r\n\tstr=scan.nextLine();\t\r\n\tSystem.out.println(\"Reverse of a String '\"+str+\"' is :\"); \r\n\tint i=str.length();\r\n\twhile(i>0)\r\n\t{\r\n\tSystem.out.print(str.charAt(i-1)); \r\n\ti--;\r\n\t}\r\n }\r\n}\r<\/code><\/pre>\n\n\n\nUsing For Loop<\/h2>\n\n\n\n
import java.util.Scanner;\r\nclass ReverseofaString\r\n{\r\n\tpublic static void main(String[ ] arg)\r\n\t{\r\n\tString str;\r\n\tchar ch;\r\n\tScanner sc=new Scanner(System.in);\r\n\tSystem.out.print(\"Enter a string : \");\r\n\tstr=sc.nextLine();\t\r\n\tSystem.out.println(\"Reverse of a String '\"+str+\"' is :\"); \r\n\tfor(int j=str.length();j>0;--j)\r\n\t{\r\n\tSystem.out.print(str.charAt(j-1)); \r\n\t}\r\n}\r<\/code><\/pre>\n\n\n\nUsing Stringbuilder\/StringBuffer<\/h2>\n\n\n\n
class Main\r\n{\r\n \/\/ Method to reverse a string in Java using `StringBuilder`\r\n public static String reverse(String str) {\r\n return new StringBuilder(str).reverse().toString();\r\n }\r\n \r\n public static void main(String[] args)\r\n {\r\n String str = \"Techie Delight\";\r\n \r\n \/\/ Note that string is immutable in Java\r\n str = reverse(str);\r<\/code><\/pre>\n\n\n\n