Should I use StringBuffer?

[GenkiSudo]

I need to make a method that takes a DNA sequence and returns it's complement.

Complementary sequence means:
1. replace every 'T' in source sequence with 'A'
2. replace every 'A' in source sequence with 'T'
3. replace every 'G' in source sequence with 'C'
4. replace every 'C' in source sequence with 'G'
5. reverse the resulting sequence

Example:
source =
"ATGAGGC"
complementary =
"GCCTCAT"

My method looks like this and works with my test strings :

public String getComplement(String sequence)
	{	
		String complement="";
		for (int i = sequence.length() - 1 ; i >= 0; i--)
		{
			switch (sequence.charAt(i))
			{
			case 'a':
				complement += 't';
				break;
			case 't':
				complement += 'a';
				break;
			case 'g':
				complement += 'c';
				break;
			case 'c':
				complement += 'g';
				break;	
			}
		}
		
				
		return complement;
	}

I've overheard my teacher mentioning StringBuffer to other students, but I didn't have time to ask him about it.
Is there any reason why I should use StringBuffer in this case?

[Norm]

You could use a StringBuffer to build the String that you are going to return (instead of using +=). StringBuffer has methods to add characters to it and to create a String. Read the API doc for more info.

[hardwired]

StringBuilder is recommended since j2se 1.5

[fishtoprecords]

As @hardwired and @Norm suggest, String is discouraged when you are manipulating the contents, as String is immutable, its better to use StringBuilder or StringBuffer.

Of course, for a one time program for a homework assignment, it makes no real difference. But as you get better, use a mutable version

[jason wang]

StringBuffer is used in the condition of there are too many String manipulation. So you should use it in your program, because your sequence is too long.

[fishtoprecords]

StringBuffer is used in the condition of there are too many String manipulation. So you should use it in your program, because your sequence is too long.

I see no evidence to agree with your claim that there are "too many" and that the sequence is "too long"

In general, its likely, but without knowing more than we do, you can't justify your claim that its too many.

[Supamagier]

As far as I know, String and StringBuilder are compiled to a StringBuffer anyways, so it doesn't really matter, regarding speed/memory.

[hungleon88]

Why dont you try with replaceAll() ??