String StringBuilder StringBuffer 性能测试

public static void main(String[] args) {

StringBuilder sbl = new StringBuilder();
StringBuffer sbf = new StringBuffer();
String str = "";
long t1 = new Date().getTime();
/**
* StringBuilder跟StringBuffer一样,但后者是线程安全的,即所有方法加上关键字synchronized,所以一般情况下考虑使用StringBuilder
* 字符串的+号操作事实上也是编译成StringBuilder,这点需要注意
*/
for (int i = 0; i < 100000; i++) {
// sbl.append("1");
// sbf.append("1");
str = str + "1";//耗时最多
}
long t2 = new Date().getTime();
System.out.println("cosume time is ---->" + (t2 - t1));
//再者,String是一个不可变性变量,涉及到字符串常量池的概念,String str = "abc"与String str = new String("abc")实现机制是不一样的

}