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。