中文XML论坛--一个XML解析问题

贴子主题：一个XML解析问题

本主题类别:

我是新手，碰到这么一个问题，请帮我下：
links.xml文件如下：
<links>
<link id="1">
       <text>JSP Insider</text>
  </link>
</links>

想把text 内容改下
程序如下：
SAXReader reader = new SAXReader();
doc = reader.read(new File("links.xml"));
//修改ID为"1"的link节点设置text 为 it's a modify
List list =doc.selectNodes("//link[@id=4]");
Iterator it = list.iterator();
while(it.hasNext()){
Element el = (Element)it.next();
el.elementByID("text").setText("it's a modify");
}

以上用的是DOM4J解析的
运行报错：
java.lang.NullPointerException
at com.qware.sjjh.tool.dom4j.DeployFileLoaderSample.editXml(DeployFileLoaderSample.java:117)
at com.qware.sjjh.tool.dom4j.DeployFileLoaderSampleTest.testEditXml(DeployFileLoaderSampleTest.java:18)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.internal.runners.TestMethodRunner.executeMethodBody(TestMethodRunner.java:99)
at org.junit.internal.runners.TestMethodRunner.runUnprotected(TestMethodRunner.java:81)
at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:34)
at org.junit.internal.runners.TestMethodRunner.runMethod(TestMethodRunner.java:75)
at org.junit.internal.runners.TestMethodRunner.run(TestMethodRunner.java:45)
at org.junit.internal.runners.TestClassMethodsRunner.invokeTestMethod(TestClassMethodsRunner.java:71)
at org.junit.internal.runners.TestClassMethodsRunner.run(TestClassMethodsRunner.java:35)
at org.junit.internal.runners.TestClassRunner$1.runUnprotected(TestClassRunner.java:42)
at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:34)
at org.junit.internal.runners.TestClassRunner.run(TestClassRunner.java:52)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)

什么原因？正确程序要怎么写呢？


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