Difference between StringBuilder and StringBuffer
StringBuffer
is synchronized, StringBuilder
is not.
StringBuilder
is faster than StringBuffer
because it's not synchronized
.
Here's a simple benchmark test:
public class Main {
public static void main(String[] args) {
int N = 77777777;
long t;
{
StringBuffer sb = new StringBuffer();
t = System.currentTimeMillis();
for (int i = N; i --> 0 ;) {
sb.append("");
}
System.out.println(System.currentTimeMillis() - t);
}
{
StringBuilder sb = new StringBuilder();
t = System.currentTimeMillis();
for (int i = N; i > 0 ; i--) {
sb.append("");
}
System.out.println(System.currentTimeMillis() - t);
}
}
}
A test run gives the numbers of 2241 ms
for StringBuffer
vs 753 ms
for StringBuilder
.
Basically, StringBuffer
methods are synchronized while StringBuilder
are not.
The operations are "almost" the same, but using synchronized methods in a single thread is overkill.
That's pretty much about it.
Quote from StringBuilder API:
This class [StringBuilder] provides an API compatible with StringBuffer, but with no guarantee of synchronization. This class is designed for use as a drop-in replacement for StringBuffer in places where the string buffer was being used by a single thread (as is generally the case). Where possible, it is recommended that this class be used in preference to StringBuffer as it will be faster under most implementations.
So it was made to substitute it.
The same happened with Vector
and ArrayList
.