StringBuilder的用法

1.使用append()追加字符串
  String str="Hello";
  StringBuilder builder=new StringBuilder(str);
  System.out.println(builder.append("World"));//HelloWorld
  builder.append("World");
  System.out.println(builder.toString());//HelloWorldWorld


2.使用insert()插入字符串
  String str="World";
  StringBuilder builder=new StringBuilder(str);
  builder.insert(0, "Hello");
  System.out.println(builder.toString());//HelloWorld


3.使用delete()删除字符串
  String str="HelloWorld";
  StringBuilder builder=new StringBuilder(str);
  builder.delete(0, 5);
  System.out.println(builder.toString());//World


4.使用replace()替换字符串
  String str="HelloHello";
  StringBuilder builder=new StringBuilder(str);
  builder.replace(5, 10,"World");
  System.out.println(builder.toString());//HelloWorld


5.使用reverse()字符串反转
  String str="HelloWorld";
  StringBuilder builder=new StringBuilder(str);
  builder.reverse();
  System.out.println(builder.toString());//dlroWolleH


6.StringBuffer 和StringBuilder的区别：
  StringBuffer是线程安全的，同步处理的，性能稍慢；
  StringBuilder是非线程安全的，并发处理的，性能稍快。