我的项目存在错误
SEVERE：调用动作时收到'java.lang.NullPointerException' 组件'loginButton'SEVERE的监听器'＃{tableBean.addNew}'： 显示java.lang.NullPointerException
这是我的addNew函数：
public void addNew(ActionEvent actionEvent) throws SQLException {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
initiate_ddate=sdf.format(initiateddate);
teststart_date=sdf.format(teststartdate);
scheduledend_date=sdf.format(scheduledenddate);
revised_end=sdf.format(revisedend);
System.err.println("erorrrrrrrrrr");
Connection connadd = new Connector().getConn();
Statement stmt = connadd.createStatement();
String sql2 = "INSERT INTO status (`name`, `initiateddate`, `agreementstatus`, `testingdoc`, `teststartdate`, `scheduledenddate`, `teststatus`, `revisedend`, `launcstatus`) VALUES ( '" + name + "' , '" + initiate_ddate + "' , '" + agreement_status + "', '" + testing_doc + "', '" + teststart_date + "', '" + scheduledend_date + "', '" + test_status + "', '" + revised_end + "', '" + launc_status + "' ); ";
stmt.executeUpdate(sql2);
FacesMessage msg = new FacesMessage("Project Edited", name + " " + initiate_ddate + " " + agreement_status + " " + testing_doc + " " + teststart_date + " " + scheduledend_date + " " + test_status + " " + revised_end + " " + launc_status);
FacesContext.getCurrentInstance().addMessage(null, msg);
}
这是什么原因？
这是堆栈跟踪：
SEVERE: Received 'java.lang.NullPointerException' when invoking action listener '#{tableBean.addNew}' for component 'loginButton'
SEVERE: java.lang.NullPointerException
at java.util.Calendar.setTime(Calendar.java:1070)
at java.text.SimpleDateFormat.format(SimpleDateFormat.java:859)
at java.text.SimpleDateFormat.format(SimpleDateFormat.java:852)
at java.text.DateFormat.format(DateFormat.java:316)
at table.TableBean.addNew(TableBean.java:192)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.el.parser.AstValue.invoke(AstValue.java:254)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:302)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:148)
at javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769)
at javax.faces.component.UICommand.broadcast(UICommand.java:300)
at javax.faces.component.UIData.broadcast(UIData.java:1093)
at javax.faces.component.UIData.broadcast(UIData.java:1093)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:619)
SEVERE: JSF1073: javax.faces.event.AbortProcessingException caught during processing of INVOKE_APPLICATION 5 : UIComponent-ClientId=form_tab:tabView, Message=/index.xhtml @234,223 actionListener="#{tableBean.addNew}": java.lang.NullPointerException
SEVERE: /index.xhtml @234,223 actionListener="#{tableBean.addNew}": java.lang.NullPointerException
javax.faces.event.AbortProcessingException: /index.xhtml @234,223 actionListener="#{tableBean.addNew}": java.lang.NullPointerException
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:182)
at javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769)
at javax.faces.component.UICommand.broadcast(UICommand.java:300)
at javax.faces.component.UIData.broadcast(UIData.java:1093)
at javax.faces.component.UIData.broadcast(UIData.java:1093)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
at java.util.Calendar.setTime(Calendar.java:1070)
at java.text.SimpleDateFormat.format(SimpleDateFormat.java:859)
at java.text.SimpleDateFormat.format(SimpleDateFormat.java:852)
at java.text.DateFormat.format(DateFormat.java:316)
at table.TableBean.addNew(TableBean.java:192)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.el.parser.AstValue.invoke(AstValue.java:254)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:302)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:148)
... 35 more
答案 0 :(得分：1)
NullpointerExceptions通常很容易解决，在这种情况下也是如此：
Trick是在stacktrace中查找你拥有的一段代码
SEVERE: java.lang.NullPointerException
at java.util.Calendar.setTime(Calendar.java:1070)
at java.text.SimpleDateFormat.format(SimpleDateFormat.java:859)
at java.text.SimpleDateFormat.format(SimpleDateFormat.java:852)
at java.text.DateFormat.format(DateFormat.java:316)
at table.TableBean.addNew(TableBean.java:192)
在这种情况下，它是table.TableBean.addNew方法在DateFormat上执行格式
你正在做其中的4个（我不知道第192行的内容）：
initiate_ddate=sdf.format(initiateddate);
teststart_date=sdf.format(teststartdate);
scheduledend_date=sdf.format(scheduledenddate);
revised_end=sdf.format(revisedend);
根本原因是以下变量之一为null。它被传递给format函数并抛出一个NPE