String and StringBuffer

[vipul bondugula]

Hi Every one,

I hava a reverse string program which i coded by using both String and StringBuffer.

I am posting it ..

import java.lang.StringBuffer;
public class ExampleOne {

	public static String reverse(String s)
	{
		if(s.length()<=0)
			throw new EmptyStringFoundException("Empty String Provided");
		else
		{
			
			//This part of code i am writing in two ways. below the code u check the code..
		}
		return s;
	}
	public static void main(String[] args) {
		
		try
		{
			System.out.println("Reverse of java ranch is: "+reverse("javaranch"));
		}catch(EmptyStringFoundException e)
		{
			System.out.println(e.getMessage());
		}
		

	}

}

one way is

StringBuffer sb = new StringBuffer(s);
s = sb.reverse().toString();

the other way is

String reversedString = "";
for(int i = 0;i<s.length-1;i++)
{
reversedString +=  s.charAt(i);
}

In both ways iam getting correct output..
My doubt is in the last code..
I am concatenating each char to string.This means each time i add a character a new string is created.I am guessing it..Is it right?

[Winston Gutkowski]

vipul bondugula wrote:I am concatenating each char to string.This means each time i add a character a new string is created.I am guessing it..Is it right?

Yes.

Winston

[vipul bondugula]

Thanks Winston,

I gussed the response.Any way once again thank you.

Which one among String and StringBuffer is better to use? Explain in single user and multi-user applications..

I mean single thread and multi-thread applications..

Thanks & Regards
Vipul Kumar.

[John Jai]

Probably you are asking for StringBuffer vs Builder in a multi threaded environment?

[Rob Spoor]

The number of threads doesn't matter. Strings are immutable, and the StringBuilder (which should be preferred over StringBuffer unless you really need synchronization) is a local variable and therefore available for only the current thread.

What you should take into account is performance. The String concatenation will create quite a lot of new objects, whereas the StringBuilder / StringBuffer solution will only create the StringBuilder / StringBuffer and the resulting reversed String. That's definitely better.

I have one question about your logic though - why not allow an empty String? An empty String reversed is the same empty String. Instead of throwing an exception, simply return s itself.

[vipul bondugula]

Thanks Rob,

I got a better answer.Actually i am working on custom exception handling. This is an example in kathy sierra scjp book. after completion on working on this example i got the doubt about String and StringBuffer


Thanks once again for everyone..

[Winston Gutkowski]

vipul bondugula wrote:This is an example in kathy sierra scjp book. after completion on working on this example i got the doubt about String and StringBuffer

Just a heads-up for you: Most of the sample code in the scjp book is written to help you to pass the exam, and it's very good for that. It should not, however, be taken as an example of how to do stuff; in fact some of it is downright awful.

Winston

[Campbell Ritchie]

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