使用TimerTask调用requestContext.execute时出现了nullpointer异常。
单击按钮时启动generateTimesStep（）。 在每秒调用该计时器以更新地图上的位置。
问题是当由timer
调用时，execute函数为nullGenerateTimeStep类
public void generateTimeStep() {
requestContext = RequestContext.getCurrentInstance();
requestContext.execute("createPoint(" + 1 + "," + lat1 + "," + lng1 + ")");
RequestContext.setCurrentInstance(requestContext);
timer.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
System.out.println("Timer called");
if (lat1 < lat2) {
lat1 = lat1 + 0.000001;
}
if (lng1 < lng2) {
lng1 = lng1 + 0.000001;
}
if (!Objects.equals(lng1, lng2) || !Objects.equals(lat1, lat2)) {
requestContext = RequestContext.getCurrentInstance();
//if (requestContext != null) {
// System.out.println("request aint null");
requestContext.execute("updatePoint(" + 1 + "," + lat1 + "," + lng1 + ")"); //NULLPOINTER
// }
}
}
}, 0, 1000);
}
的Javascript
function createPoint(vIndex,vLat, vLng){
var point = new MQA.Poi({lat: vLat, lng: vLng});
point.setRolloverContent("Indi's Cribbb!!!!");
var icon1 = new MQA.Icon("http://example.com/pictures/Car.png", 50, 29);
point.setIcon(icon1);
window.map.addShape(point);
mycars[vIndex] = point;}
function updatePoint(vIndex, vLat, vLng)
{
var point = mycars[vIndex];
point.setLatLng({lat:vLat,lng:vLng});
}
堆栈跟踪
java.lang.ClassCastException: cannot assign instance of java.lang.String to field beans.IndexBean.timer of type java.util.Timer in instance of beans.IndexBean
at java.io.ObjectStreamClass$FieldReflector.setObjFieldValues(ObjectStreamClass.java:2089)
at java.io.ObjectStreamClass.setObjFieldValues(ObjectStreamClass.java:1261)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1999)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
at org.apache.catalina.session.StandardSession.readRemainingObject(StandardSession.java:2078)
at org.apache.catalina.session.StandardSession.readObject(StandardSession.java:1986)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1896)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
at org.apache.catalina.session.StandardSession.deserialize(StandardSession.java:1272)
at org.apache.catalina.session.StandardManager.readSessions(StandardManager.java:555)
at com.sun.enterprise.web.WebModule.loadSessions(WebModule.java:1762)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:2280)
at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1924)
at com.sun.enterprise.web.WebApplication.start(WebApplication.java:139)
at org.glassfish.internal.data.EngineRef.start(EngineRef.java:122)
at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:291)
at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:352)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:497)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:219)
at org.glassfish.deployment.admin.DeployCommand.execute(DeployCommand.java:491)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$2.execute(CommandRunnerImpl.java:537)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:546)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1423)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$1500(CommandRunnerImpl.java:108)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1762)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1674)
at org.glassfish.deployment.admin.ReDeployCommand.execute(ReDeployCommand.java:131)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$2$1.run(CommandRunnerImpl.java:527)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$2$1.run(CommandRunnerImpl.java:523)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:360)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$2.execute(CommandRunnerImpl.java:522)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:546)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1423)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$1500(CommandRunnerImpl.java:108)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1762)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1674)
at com.sun.enterprise.v3.admin.AdminAdapter.doCommand(AdminAdapter.java:534)
at com.sun.enterprise.v3.admin.AdminAdapter.onMissingResource(AdminAdapter.java:224)
at org.glassfish.grizzly.http.server.StaticHttpHandler.service(StaticHttpHandler.java:297)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:246)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:744)
Info: Loading application [AutoSysteem] at [/]
Info: AutoSysteem was successfully deployed in 11.338 milliseconds.
Warning: Context path from ServletContext: differs from path from bundle: /
Severe: Exception in thread "Timer-2"
Severe: java.lang.NullPointerException
at beans.IndexBean$1.run(IndexBean.java:91)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)