//沒有sycronized修飾method,是線程不安全的,--StringBuffer來彌補這個缺點，但速度就慢了

並沒有測試出來：：

 1 /**
 2  * 
 3  */
 4 package com.breaver.test.string;
 5 
 6 /**
 7  * @author zzf
 8  [email protected] 2017年6月22日 下午11:09:36
 9  */
10 public class TestStringBuilder implements Runnable{
11     public static StringBuilder strs=new
 
 StringBuilder("my-str:");
12     private String str;
13     /**
14      * @param args
15      */
16     
17     public static void main(String[] args) {
18         // TODO Auto-generated method stub
19 //        TestStringBuilder.test();
20         new Thread(new TestStringBuilder("123")).start();
21         new
 
 Thread(new TestStringBuilder("abc")).start();
22     }
23     public TestStringBuilder(String a) {
24         super();
25         // TODO Auto-generated constructor stub
26         str=a;
27     }
28     @Override
29     public void run() {
30         // TODO Auto-generated method stub
31         try{
32
 
             while(true){
33                 System.out.println(strs.toString());
34                 Thread.sleep(1000);
35                 strs.append(str);
36             }
37         }catch (Exception e) {
38             // TODO: handle exception
39             e.printStackTrace();
40         }
41     }
42     public static void test(){
43         StringBuilder builder =new StringBuilder();
44         System.out.println(builder.toString()+":"+builder.capacity());
45         builder.append("123");
46         System.out.println(builder.toString()+":"+builder.capacity());
47         builder.append("asssssssssssssqwqw123");
48         System.out.println(builder.toString()+":"+builder.capacity()
49         +"::fact-size:"+builder.length());
50         builder.append("Aasssssssssssssqwqw123");
51         System.out.println(builder.toString()+":"+builder.capacity()
52         +"::fact-size:"+builder.length());
53     }
54 }

java中StringBuilder為單線程做的，StringBuffer相反