Hi all , Today I am going to write a post on very popular interview
program which is How to Reverse a string in Java .
As String interview question have always been a favorite of
almost all interviewers there’s always been a program on String manipulation in
an interview .String programs vary from searching a particular word in a sentence or a file ,reverse a string
,Number of times a particular word or character appears in a sentence or file
and many more .
So today I am going to discus how to reverse a String in
java .This program also helps to find that whether a String is Palindrome or
not .
A palindrome String can be checked by comparing the original
String with the reverse of that String with the help of equals() method or “==” .If both are equal
then that means the String is palindrome .But for that first you need to know
about how to reverse a String .
The reverse of a String example I have done it in two ways.
- Reverse
of String without using reverse method or Reverse a String using CharAt()
method or Reverse a String without using String Buffer .
- Reverse
of String using reverse method or Reverse a String without using String
Buffer .
If you know both of the methods to reverse a String then you
can impress the interviewer by writing both the methods J
So , Here is the Example of
Reverse of String without using reverse method or Reverse a String using CharAt() method or
Reverse a String without using String Buffer .
import java.util.*;
class ReverseString
{
public static void main(String args[])
{
String original, reverse = "";
Scanner in = new Scanner(System.in);
System.out.println("Enter a string to reverse");
original = in.nextLine();
int length = original.length();
for ( int i = length - 1 ; i >= 0 ; i-- )
reverse = reverse + original.charAt(i);
System.out.println("Reverse of entered string is: "+reverse);
}
}
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Explanation:
1. In the above Example we are asking the user to enter a
String to reverse.
2. After calculating the length of the String we are using a
loop to get each character from end of String ( as we are starting the loop
form end) and then appending the characters using + operator .
This is quite simple example .Hope you all understand.
Now Comes the second method of Revere a String.
Reverse of String using reverse method or Reverse a String
without using String Buffer .
import java.util.*;
class InvertString
{
public static void main(String args[])
{
StringBuffer a = new StringBuffer("Java programming is fun");
System.out.println(a.reverse());
}
}
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In this example we are using StringBuffer and its reverse
method to reverse a string .
If you want input from user in StringBuffer case then you
can use the program below :
import java.util.*;
class ReverseString
{
public static void main(String args[])
{
String original ;
Scanner in = new Scanner(System.in);
System.out.println("Enter a string to reverse");
original = in.nextLine();
StringBuffer a = new StringBuffer(original);
System.out.println(a.reverse());
}
}
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So this was my post on How to Reverse a String in Java .If
you have any doubt or you know another efficient method please do write me .If
you like this post please comment below :)
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