String 和 StringBuffer

性能比较

public class StringAndStringBuffer {    String stringSample = "";    StringBuffer stringBufferSample = new StringBuffer();    public void testNewTime(){        long stringStart = System.currentTimeMillis();          for(int i=0;i<10000;i++)            stringSample = stringSample+i;              long stringEnd = System.currentTimeMillis();        long stringBufferStart = System.currentTimeMillis();            for(int j=0;j<10000;j++)            stringBufferSample.append(j);           long stringBufferEnd = System.currentTimeMillis();        System.out.println("String:        insert 10000 time cost: "+                 (stringEnd - stringStart)+" Millis");        System.out.println("StringBuffer:  insert 10000 time cost: "+                (stringBufferEnd - stringBufferStart)+" Millis");    }    public static void main(String args[]){        StringAndStringBuffer ss = new StringAndStringBuffer();        ss.testNewTime();    }}

结果：

String:        insert 10000 time cost: 212 MillisStringBuffer:  insert 10000 time cost: 0 Millis