Palindrome of string in java

Checking Palindrome of String

What is Palindrome ?

> A palindrome is number,string or phrase which reads same as backward and forward.Ex-MADAM, 121  etc

1ST CLEAR ONE THING THAT A STRING IS A IMMUTABLE CONSTANT IN JAVA. IT MEANS A STRING CAN NOT BE CHANGED. SO WE WILL USE A NEW METHOD WHICH  IS CALLED Stringbuffer ,IT IS A STRING BUT IT CAN BE MODIFIED .

Steps to do this:-
1.  take 2 string variable named a,b;
2. now take a Scanner class and make an object name s

3. take a word or sentence from user and scan it like

a=s.nextLine();

4. now use StringBuffer class and make a object named sb and pass the scanned user input string as a parameter inside it

StringBuffer sb=new Stringbuffer(a);

remember we scan "a" so we just pass it as a parameter inside StringBuffer.

5. there is many method inside StringBuffer class like 

• append()
• reverse()
• insert()
• capacity()
• reverse()
• delete(int start_index,int end_index)
• replace(
  int start_index,int end_index , string )
• deleteCharAt(int index)

in this case we use reverse() method this method it will reverse the string which is user input.

now do this,
b=sb.reverse().toString();
 we just reverse the string and we change it in String Buffer from String so we change the  StringBuffer into a string by toString() method
6. check this
if(a.equals(b))
{
print"palindrome"
}
else
{
print "not a palindrome "
}
in here we just check the string is equal or not, and according to palindrome concept if it is equal then it will print the if block otherwise it will print the else block.

7. save and run

The Source Code

 import java.util.Scanner;
 class palindrome
 {
     public static void main(String[] args) {
         Scanner s=new Scanner(System.in);
         String a,b;
         System.out.println("enter the word");
         a=s.nextLine();
         StringBuffer sb=new StringBuffer(a);
         b=sb.reverse().toString();
         if (a.equals(b))
             {
             System.out.println("this is palindrome");
             }
         else
             {
             System.out.println("this is not a palindrome");
             }
     }
}

OUTPUT

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