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 js14         String str = builder.toString();15         System.out.println(str);16         17         builder.delete(0, 4);//your best to learn js18         String str1 = builder.toString();19         System.out.println(str1);20         //插入操作21         builder.insert(0, "we ");//we   your best to learn js22         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；