急求XML节点修改问题！！！

<roster>
<student ID="101">
<name>李华</name>
<sex>男</sex>
<birthday>1978.9.12</birthday>
<score>92</score>
<skill>Java</skill>
<skill>Oracle</skill>
<skill>C Sharp</skill>
<skill>SQL Server</skill>
</student>
<student ID="102">
<name>倪冰</name>
<sex>女</sex>
<birthday>1979.1.12</birthday>
<score>89</score>
<skill>Visual Basic</skill>
<skill>SQL Server</skill>
<skill>ASP</skill>
</student>
<student ID="103">
<name>张君宝</name>
<sex>男</sex>
<birthday>1982.9.9</birthday>
<score>100</score>
<skill>C Sharp</skill>
<skill>SQL Server</skill>
<skill>UML</skill>
</student>
<student ID="104">
<name>杨惠</name>
<sex>女</sex>
<birthday>1980.5.16</birthday>
<score>85</score>
<skill>Visual C++</skill>
<skill>SQL Server</skill>
<skill>UML</skill>
</student>
<student ID="105">
<name>崔春晓</name>
<sex>男</sex>
<birthday>1981.4.19</birthday>
<score>86</score>
<skill>UML</skill>
<skill>C Sharp</skill>
<skill>XML</skill>
<skill>SQL Server</skill>
</student>
<student ID="106">
<name>王动</name>
<sex>男</sex>
<birthday>1981.4.19</birthday>
<score>59</score>
<skill>UML</skill>
<skill>C Sharp</skill>
<skill>XML</skill>
<skill>SQL Server</skill>
</student>
<student ID="107">
<name>李寻欢</name>
<sex>男</sex>
<birthday>1981.4.19</birthday>
<score>58</score>
<skill>UML</skill>
<skill>C Sharp</skill>
<skill>XML</skill>
<skill>SQL Server</skill>
</student>我想把<student ID="102">修改为<student ID="B102">,java中应该怎么做？