- 长度和内容可变的[[String]] [[字符串]]
- ```java
  //创建一个16个字符串
  StringBulider s = new StringBuilder();//可传入字符串，长度
  a.append("Hello,World");
  a.append("nihao");
  ```
- [[apppend]]
- [[insert]]
- [[capacity]]
- [[length]]
- [[setCharAt]]
- [[delete]]
- [[reverse]]
- [[substring]]
- [[indexOf]]
- [[lastIndexOf]]
-