I am trying to check if the given string is palindrome or not. I am getting errors .

Question

1.50/5 (2 votes)

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I am getting the following error,

prog.java:10: error: cannot find symbol
System.out.System.out.println("No string");

What I have tried:

I am trying the following code for this,

Java

class GFG {
	public static void main (String[] args) {
		String str= "gadag"; 
		if(str==null)
		{
		    System.out.System.out.println("No string");
		}
	   StringBuilder strBuilder = new StringBuilder(str);
		 strBuilder.reverse();
	     Boolean status = strBuilder.equals(str);
		 System.out.println(status);
		 
		}
	}

Posted 29-Jul-19 6:30am

radhikay

Updated 29-Jul-19 8:24am

Afzaal Ahmad Zeeshan

v2

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Patrice T · Accepted Answer · 2019-07-29T06:43:00

Solution 1

Just an idea:

Java

System.out.System.out.println("No string");

Did you read the code to try to understand what is wrong in this code ? or is it just easier to ask us ?
You should be able to find such error by yourself.

Posted 29-Jul-19 6:43am

Patrice T

OriginalGriff · Accepted Answer · 2019-07-29T08:12:00

Why reverse the string? That's OK for little strings, but a serious waste of time and memory for large ones.
Instead, consider this: a string can be thought of as an array of characters, so you can use charAt(index) to return a single character.
If you loop through half as many characters as there are in the string, then you can compare the first with the last, the second with the second to last, ... all the way to the center. If you find a single difference, it's not a palindrome.
That way, you are using less memory, less processor, and it's generally a much better idea ... for real efficiency, use two indexes: one at the first char, one at the last, and move one up and one down each time round the loop.