在程序中需要使用到的字符串大致可以分为两大类，一类是创建之后不需要做修改和变动的字符串常量，另一类则是创建之后需要添加，插入和修改等更改的字符串变量。在java中，对于字符串常量对象则使用String类，它提供了许多诸如比较（compareTo），查找（indexOf）之类的操作，而对于字符串变量对象则使用StringBuffer类，它提供了扩充（append），插入（insert）等操作。-In the procedure requires the use of the string can be broadly classified into two categories, do not need to do is to create after the modifications and changes in string constants, and the other is created after the need to add, insert and modify characters, such as changes string variable. In java, for the constant string object is used String category, it provides a lot of comparison, such as (compareTo), search (indexOf) type operation, and for using a string variable object StringBuffer category, which provides expanded (append ), insert (insert) and other operations.