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JSF/Primefacesを使用してフォームを作成して、ユーザーがデータを入力できるようにしています。データへのアクセスを許可する汎用クラスInputを定義しました（異なるフィールドには異なる型があるため）。私は例外 java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Doubleジェネリックの使用時にjava.lang.Doubleにjava.lang.Doubleをキャストできません
を取得しようとするとInput<Double>として宣言されたオブジェクトからデータを取得する場合しかし、私はInputに格納された値がダブルである必要があり、これが起こっている理由として、やや混乱していますか？これを引き起こしていることを誰かが正しい方向に向けることができたら、私はとても感謝しています。
<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>
form.xhtml
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;
}
}
エラーがFormBean.javaでsubmit()方法でライン13で生じます。 System.out.println(formatDouble(amount.getValue()));
追加情報が必要な場合はお知らせください。 ありがとう！
EDIT：追加スタックトレース：
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
どのラインでエラーが発生しますか？ –
エラーは、FormBean.javaのsubmit（）メソッドの13行目で発生します。 'System.out.println（formatDouble（amount.getValue（）））; ' –
ダブルキャストを削除したときの出力'else String.format（"％2f "、（double）d）;'を返す。 –