StringBuilder的使用与总结

StringBuilder 用于解决字符串频繁修改带来的内存消耗
所以将来有频繁修改字符串内容这样的操作时，首先使用StringBuiler

 1 public class demo01 {
 2     public static void main(String[] args) {
 3         //内部默认为空字符串
 4         StringBuilder builder = new StringBuilder();
 5         
 6         //内部默认为HelloWorld
 7         StringBuilder builder1 = new StringBuilder("HelloWorld");
 8         
 9         //append用于在字符串末尾追加
10         builder.append("Try your best to learn Java");
11         
12         //replace用于替换
13         builder.replace(23,28,"js");//Try your best to learn js
14         String str = builder.toString();
15         System.out.println(str);
16         
17         builder.delete(0, 4);//your best to learn js
18         String str1 = builder.toString();
19         System.out.println(str1);
20         //插入操作
21         builder.insert(0, "we ");//we   your best to learn js
22         String str2 = builder.toString();
23         System.out.println(str2);
24     }
25 }

builder.reverse()翻转字符串

 1 /**
 2  * builder.reverse()翻转字符串
 3  * @author Administrator
 4  *判断回文
 5  */
 6 public class demo02 {
 7     public static void main(String[] args) {
 8         String str = "雾锁山头山锁雾";
 9         StringBuilder builder = new StringBuilder(str);
10         builder.reverse();
11         String str1 = builder.toString();
12         if(str.equals(str1)){
13             System.out.println("yes");
14         }
15         else{
16             System.out.println("no");
17         }
18     }
19 }

总结：

StringBuilder 是可变字符串，字符串的内容计算建议采用StringBuilder实现，这样性能会好一些；

java的字符串连接过程是利用StringBuilder实现的

String s ='ab';
String s1 = s+'de'+1;
String s1 = new StringBuilder(s).append("de").append("1").toString();

StringBuffer是线程安全的，同步处理，性能稍慢；

StringBuilder是非线程安全的，并发处理，性能稍快；