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Ich erstelle ein Formular mit JSF/Primefaces, damit ein Benutzer Daten eingeben kann. Ich habe eine generische Klasse Input definiert, um den Zugriff auf die Daten zu ermöglichen (da verschiedene Felder unterschiedliche Typen haben). Allerdings, wenn ich Daten von einem Objekt als Input<Double> erklärt versuchen und abrufen bekomme ich die Ausnahme java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Doublejava.lang.String kann nicht in java.lang.Double umgewandelt werden, wenn Generics verwendet werden
Ich bin ein wenig verwirrt, warum dies geschieht als in Input gespeicherten Wert sollte ein Doppel sein? Wenn mir jemand in die richtige Richtung zeigen könnte, was das verursacht, wäre ich sehr dankbar.
FormBean.java
@ManagedBean(name="form", eager=true)
@SessionScoped
public class FormBean {
private Input<String> name = new Input<>();
private Input<Date> date = new Input<>();
private Input<Double> hours = new Input<>();
private Input<Double> amount = new Input<>();
public void submit(){
System.out.println(name.getValue());
System.out.println(parseDate(date.getValue(),"dd/MM/yy"));
System.out.println(formatDouble(hours.getValue()));
System.out.println(formatDouble(amount.getValue()));
}
public static String parseDate(Date date, String format){
if(date == null) return "";
DateFormat df = new SimpleDateFormat(format);
return df.format(date);
}
public static String formatDouble(Double d){
if(d==null) return "";
else return String.format("%.2f", (double)d);
}
//-------------------GETTERS AND SETTERS----------------------------
public Input<String> getName() {
return name;
}
public Input<Date> getDate() {
return date;
}
public Input<Double> getHours() {
return hours;
}
public Input<Double> getAmount() {
return amount;
}
}
Input.java
public class Input<T> {
private T value;
private String styleClass = "inputdefault";
public T getValue() {
return value;
}
public void setValue(T value) {
this.value = value;
}
public String getStyleClass() {
return styleClass;
}
public void setStyleClass(String styleClass) {
this.styleClass = styleClass;
}
}
form.xhtml
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:p="http://primefaces.org/ui">
<h:head>
<ui:define name="title">Form</ui:define>
</h:head>
<h:body>
<h:form id="form">
<p:panelGrid id="formGrid" style="text-align:center;margin:20px;" columns="2" layout="grid">
<h:outputText class="output" value="Name"/>
<p:inputText id="name" class="#{form.name.styleClass}" value="#{form.name.value}"/>
<h:outputText class="output" value="Date:"/>
<p:calendar class="#{form.date.styleClass}" value="#{form.date.value}" pattern="dd/MM/yy"/>
<h:outputText class="output" value="Hours:"/>
<p:inputNumber id="hours" class="#{form.hours.styleClass}" value="#{form.hours.value}" decimalPlaces="2"/>
<h:outputText class="output" value="Amount:"/>
<p:inputNumber class="#{form.amount.styleClass}" value="#{form.amount.value}" decimalPlaces="2"/>
</p:panelGrid>
<p:commandButton value="Submit" update="@form" action="#{form.submit}" class="left"/>
</h:form>
</h:body>
</html>
Der Fehler tritt bei der Linie 13 in den submit() Verfahren in FormBean.java: System.out.println(formatDouble(amount.getValue()));
Wenn Sie weitere Informationen benötigen, lassen Sie es mich wissen. Danke!
EDIT: Added Stacktrace:
Jun 12, 2017 1:10:55 PM com.sun.faces.lifecycle.InvokeApplicationPhase execute
WARNING: #{form.submit}: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
javax.faces.FacesException: #{form.submit}: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
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:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:658)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: javax.faces.el.EvaluationException: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
... 26 more
Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
at FormBean.submit(FormBean.java:20)
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.apache.el.parser.AstValue.invoke(AstValue.java:278)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:274)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
... 27 more
Jun 12, 2017 1:10:55 PM com.sun.faces.context.AjaxExceptionHandlerImpl handlePartialResponseError
SEVERE: javax.faces.el.EvaluationException: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
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:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:658)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
at FormBean.submit(FormBean.java:20)
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.apache.el.parser.AstValue.invoke(AstValue.java:278)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:274)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
... 27 more
zu erhalten In welcher Zeile tritt der Fehler auf? –
Der Fehler tritt bei der Zeile 13 in der Methode submit() in FormBean.java auf: 'System.out.println (formatDouble (amount.getValue()));' –
welche Ausgabe erhalten Sie, wenn Sie die doppelte Besetzung entfernen 'else return String.format ("%. 2f ", (double) d);'? –