Question

我有一个Java方法（getTrucks()），它抛出ClassCastException: string can't be cast to double。

该方法属于FoodTruckServiceImpl，实现FoodTruckService。

我通过解析器检索对象，因此它们以正确的类型存储。

以下是方法：

public List<Truck> getTrucks() {

PersistenceManager pm = getPersistenceManager();
List<Truck>  trucklist = new ArrayList<Truck>();

try {
    Extent e = pm.getExtent(Truck.class, true);
    Iterator iter = e.iterator();
    int count = 0;

    while(iter.hasNext()) {
        count++;
        System.out.println(count);
        Truck t = (Truck) iter.next();
        trucklist.add(t);
    }

    if(count>0){
        System.out.println("get to here(count>0)?!!");
        return trucklist;
    }
} finally {
     pm.close();
}

System.out.println("get to here?!!");
return this.trucklist.getTruckList();

}

Truck Class:
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Truck {

@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Long id;
@Persistent
private String key;
@Persistent
private String vendorType;
@Persistent
private String status;
@Persistent
private String businessName;
@Persistent
private String location;
@Persistent
private String description;
@Persistent
private double lat;
@Persistent
private double lon;
@Persistent
private Date createDate;

//constructor for food truck
public Truck() {
    this.createDate = new Date();
}

public Truck(String symbol, String type, String status, String businessName, String location, String description, double lat, double lon) {
    this();
    this.key = symbol;
    this.vendorType = type;
    this.status = status;
    this.businessName = businessName;
    this.location = location;
    this.description = description;
    this.lat = lat;
    this.lon = lon;
}

public Long getId() {
    return this.id;
}

public String getTruck() {
    return this.key;
}

public void setKey(String key) {
    this.key = key;
}

public String getVendorType() {
    return this.vendorType;
}

public void setVendorType(String vendorType) {
    this.vendorType = vendorType;
}

public String getStatus() {
    return this.status;
}

public void setstatus(String status) {
    this.status = status;
}

public String getBusinessName() {
    return this.businessName;
}

public void setBusinessName(String businessName) {
    this.businessName = businessName;
}

public String getLocation() {
    return this.location;
}

public void setLocation(String location) {
    this.location = location;
}

public String getDescription() {
    return this.description;
}

public void setDescription(String description) {
    this.description = description;
}

public double getLat() {
    return this.lat;
}

public void setLat(double lat) {
    this.lat = lat;
}

public double getLon() {
    return this.lon;
}

public void setLon(double lon) {
    this.lon = lon;
}

public Date getCreateDate() {
    return this.createDate;
}




}

它会抛出以下错误：

SEVERE: javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
        com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.util.List com.cpsc310.foodtrucker.client.FoodTruckService.getTrucks()' threw an unexpected exception: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double
        at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:389)
        at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:579)
        at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:265)
        at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:305)
        at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
        at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:127)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
        at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
        at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
        at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
        at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
        at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
        at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
        at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:98)
        at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
        at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:487)
        at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
        at org.mortbay.jetty.Server.handle(Server.java:326)
        at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
        at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938)
        at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
        at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
        at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
        at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
        at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
        Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to      java.lang.Double
        at com.google.appengine.datanucleus.FetchFieldManager.fetchDoubleField(FetchFieldManager.java:140)
        at org.datanucleus.state.AbstractStateManager.replacingDoubleField(AbstractStateManager.java:2256)
        at com.cpsc310.foodtrucker.client.Truck.jdoReplaceField(Truck.java)
        at com.cpsc310.foodtrucker.client.Truck.jdoReplaceFields(Truck.java)
        at org.datanucleus.state.JDOStateManager.replaceFields(JDOStateManager.java:1935)
        at org.datanucleus.state.JDOStateManager.replaceFields(JDOStateManager.java:1962)
        at com.google.appengine.datanucleus.EntityUtils$1.fetchFields(EntityUtils.java:974)
        at org.datanucleus.state.JDOStateManager.loadFieldValues(JDOStateManager.java:764)
        at org.datanucleus.state.JDOStateManager.initialiseForHollow(JDOStateManager.java:205)
        at org.datanucleus.state.StateManagerFactory.newForHollowPopulated(StateManagerFactory.java:89)
        at org.datanucleus.state.ObjectProviderFactory.newForHollowPopulated(ObjectProviderFactory.java:75)
        at org.datanucleus.ObjectManagerImpl.findObject(ObjectManagerImpl.java:2882)
        at com.google.appengine.datanucleus.EntityUtils.entityToPojo(EntityUtils.java:1014)
        at com.google.appengine.datanucleus.query.DatastoreQuery$2.apply(DatastoreQuery.java:229)
        at com.google.appengine.datanucleus.query.DatastoreQuery$2.apply(DatastoreQuery.java:226)
        at com.google.appengine.datanucleus.query.LazyResult.resolveNext(LazyResult.java:96)
        at com.google.appengine.datanucleus.query.LazyResult.resolveAll(LazyResult.java:121)
        at com.google.appengine.datanucleus.query.StreamingQueryResult.closingConnection(StreamingQueryResult.java:90)
        at org.datanucleus.store.query.AbstractQueryResult.disconnect(AbstractQueryResult.java:108)
        at com.google.appengine.datanucleus.query.StreamingQueryResult.disconnect(StreamingQueryResult.java:78)
        at com.google.appengine.datanucleus.query.JDOQLQuery$1.managedConnectionPreClose(JDOQLQuery.java:199)
        at com.google.appengine.datanucleus.DatastoreConnectionFactoryImpl$DatastoreManagedConnection.close(DatastoreConnectionFactoryImpl.java:147)
        at org.datanucleus.store.connection.ConnectionManagerImpl.closeAllConnections(ConnectionManagerImpl.java:181)
        at org.datanucleus.store.AbstractStoreManager$1.preClose(AbstractStoreManager.java:260)
        at org.datanucleus.ObjectManagerImpl.close(ObjectManagerImpl.java:1112)
        at org.datanucleus.api.jdo.JDOPersistenceManager.internalClose(JDOPersistenceManager.java:359)
            at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.releasePersistenceManager(JDOPersistenceManagerFactory.java:1106)
        at    org.datanucleus.api.jdo.JDOPersistenceManager.close(JDOPersistenceManager.java:343)
        at  com.cpsc310.foodtrucker.server.FoodTruckServiceImpl.getTrucks(FoodTruckServiceImpl.java:105)
         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at   sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at     com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:115)
        at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:561)
            ... 40 more

有人可以帮我解决这个问题吗？

Answer 1

当方法返回List<Truck>时，只需返回trucklist NOT this.trucklist.getTruckList()

Answer 2

就我而言，问题是ToastAndroid出现的，所以我只是删除了行，错误消失了

Platform.OS === "android"
      ? ToastAndroid.show(
          "Congratulations\n",
          "Your profile has been updated",
          ToastAndroid.SHORT
        )
      : Alert.alert("Congratulations", "Your profile has been updated");

只要小心地实施Toast，一切都会很好

ClassCastException：string不能强制转换为double

2 个答案: