使用HTMLPanel和addAndReplaceElement方法的GWT NoSuchElementException

Question

这里有一些解释。

如果我的HTML页面包含：

<div id="cancel_date"> 
    <h3 id="cancel_date_title"></h3> 

    <table align="center"> 
    <tr> 
     <td id="cancel_date_labelDetailService"></td> 
     <td id="cancel_date_detailService"></td> 
    </tr> 
    </table> 
</div> 

如果我的代码包含

HTMLPanel container = HTMLPanel.wrap(Document.get().getElementById("cancel_date")); 

public void init(){ 
container.add(getMyWidget(), "cancel_date_detailService"); 
} 

public void reload(){ 
container.addAndReplaceElement(getService(), "cancel_date_detailService"); 
} 

我第一次加载我的网页，我的方法的init（）实现。第二次和之后，我调用reload（）方法。 我第一次调用reload（）方法时，一切正常。但之后，我有这样一个NoSuchElementException：

ERROR: Uncaught exception escaped 
com.google.gwt.event.shared.UmbrellaException: One or more exceptions caught, see full set in UmbrellaException#getCauses 
    at com.google.gwt.event.shared.EventBus.castFireEvent(EventBus.java:69) 
    at com.google.gwt.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:57) 
    at be.mims.bookme.client.gui.component.MyCellTableFuturDates$7.onSuccess(MyCellTableFuturDates.java:134) 
    at be.mims.bookme.client.gui.component.MyCellTableFuturDates$7.onSuccess(MyCellTableFuturDates.java:1) 
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:232) 
    at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287) 
    at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395) 
    at sun.reflect.GeneratedMethodAccessor88.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) 
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) 
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172) 
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337) 
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218) 
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136) 
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561) 
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269) 
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91) 
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java) 
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213) 
    at sun.reflect.GeneratedMethodAccessor79.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) 
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) 
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172) 
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292) 
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546) 
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363) 
    at java.lang.Thread.run(Thread.java:722) 
Caused by: java.util.NoSuchElementException: cancel_date_detailService 
    at com.google.gwt.user.client.ui.HTMLPanel.addAndReplaceElement(HTMLPanel.java:224) 
    at be.mims.bookme.client.gui.FactoryCancelDate.showCancelDate(FactoryCancelDate.java:128) 
    at be.mims.bookme.client.BookMe.show(BookMe.java:277) 
    at be.mims.bookme.client.event.StateEvent.dispatch(StateEvent.java:31) 
    at be.mims.bookme.client.event.StateEvent.dispatch(StateEvent.java:1) 
    at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1) 
    at com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40) 
    at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193) 
    at com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88) 
    at com.google.gwt.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:52) 
    at com.google.gwt.event.shared.EventBus.castFireEvent(EventBus.java:67) 
    at com.google.gwt.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:57) 
    at be.mims.bookme.client.gui.component.MyCellTableFuturDates$7.onSuccess(MyCellTableFuturDates.java:134) 
    at be.mims.bookme.client.gui.component.MyCellTableFuturDates$7.onSuccess(MyCellTableFuturDates.java:1) 
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:232) 
    at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287) 
    at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395) 
    at sun.reflect.GeneratedMethodAccessor88.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) 
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) 
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172) 
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337) 
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218) 
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136) 
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561) 
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269) 
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91) 
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java) 
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213) 
    at sun.reflect.GeneratedMethodAccessor79.invoke(Unknown Source) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) 
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) 
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172) 
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292) 
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546) 
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363) 
    at java.lang.Thread.run(Thread.java:722) 

如果我进入SimpleEventBus类地方是例外：

java.util.NoSuchElementException: cancel_date_detailService 
at com.google.gwt.user.client.ui.HTMLPanel.addAndReplaceElement(HTMLPanel.java:224) 
at be.mims.bookme.client.gui.FactoryDetailRdv.showDetailsDate(FactoryDetailRdv.java:72) 
at be.mims.bookme.client.BookMe.show(BookMe.java:228) 
at be.mims.bookme.client.event.StateEvent.dispatch(StateEvent.java:31) 
at be.mims.bookme.client.event.StateEvent.dispatch(StateEvent.java:1) 
at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1) 
at com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40) 
at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193) 
at com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88) 
at com.google.gwt.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:52) 
at com.google.gwt.event.shared.EventBus.castFireEvent(EventBus.java:67) 
at com.google.gwt.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:57) 
at be.mims.bookme.client.gui.component.MyCellTableFuturDates$7.onSuccess(MyCellTableFuturDates.java:130) 
at be.mims.bookme.client.gui.component.MyCellTableFuturDates$7.onSuccess(MyCellTableFuturDates.java:1) 
at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:232) 
at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287) 
at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395) 
at sun.reflect.GeneratedMethodAccessor174.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:601) 
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) 
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) 
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172) 
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337) 
at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218) 
at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136) 
at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561) 
at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269) 
at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91) 
at com.google.gwt.core.client.impl.Impl.apply(Impl.java) 
at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213) 
at sun.reflect.GeneratedMethodAccessor166.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:601) 
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) 
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) 
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172) 
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292) 
at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546) 
at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363) 
at java.lang.Thread.run(Thread.java:722) 

我使用GWT 2.4.0

非常感谢求助！！！

Answer 1

顾名思义，addAndReplaceElement找到元素，用给定的小部件替换。一旦你为一个元素调用addAndReplaceElement一次，那一个元素就消失了，所以第二个调用显然不会找到它，导致你看到的NoSuchElementException。

如果你想用另一个替换你的widget，那么你需要包裹它的元素（即调用add代替addAndReplaceElement），并使用remove删除以前的小部件。

Answer 2

很难说没有看看你的getService（）方法，但我最好的猜测是，在第一次调用reload（）之后，它正在寻找的元素正在被替换。隔一段时间，要被替换的块不再存在，抛出异常。