Java StringBuilder和StringBuffer之间的区别

StringBuilder比StringBuffer

synchronized

这是一个简单的基准测试：

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);        }    }}

一个试运行给出的数字2241 ms为StringBufferVS 753 ms的StringBuilder。