Question

我有两个实现Parcelable的类。我试图通过对活动的意图传递每个类的对象。但是，当我尝试访问其中一个对象时，它认为它是另一个对象的类型并尝试强制转换它。

头等舱

public class Track implements Parcelable{

private String trackOwner;
private String trackName;
private Double sumDistace;

public final static String POINTTOPOINT = "POINTTOPOINT";
public final static String CIRCUIT = "CIRCUIT";

private String trackType;
private ArrayList<Checkpoint> checkpoints;

public Track(String trackOwner, String trackName, String trackType, Double sumDistace){

    this.trackOwner = trackOwner;
    this.trackName = trackName;
    this.trackType = trackType;
    checkpoints = new ArrayList<Checkpoint>();
    this.sumDistace = sumDistace;

}

public Track(){

}

public Track(Parcel in){
    readFromParcel(in);
}

public static final Parcelable.Creator CREATOR = new Parcelable.Creator(){

    @Override
    public Object createFromParcel(Parcel source) {
        return new User(source);
    }

    @Override
    public Object[] newArray(int size) {
        return new User[size];
    }
};

public String getTrackOwner(){
    return this.trackOwner;
}

public String getTrackName(){
    return this.trackName;
}

public String getTrackType(){
    return this.trackType;
}

public Double getSumDistace(){return this.sumDistace; }

public void setCheckpoints(ArrayList<Checkpoint> checkpoints){
    this.checkpoints = checkpoints;
}

public void setSumDistace(double sumDistace){
    this.sumDistace = sumDistace;
}

public void addCheckpoint(Checkpoint checkpoint){
    checkpoints.add(checkpoint);
}

public ArrayList<Checkpoint> getCheckpoints(){
    return this.checkpoints;
}


@Override
public int describeContents() {
    return 0;
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(trackOwner);
    dest.writeString(trackName);
    dest.writeString(trackType);
    dest.writeTypedList(checkpoints);
    dest.writeDouble(sumDistace);

}

public void readFromParcel(Parcel in){
    trackOwner = in.readString();
    trackName = in.readString();
    trackType = in.readString();
    in.readTypedList(checkpoints,Checkpoint.CREATOR);
    sumDistace = in.readDouble();
}
}

第二类

public class User implements Parcelable{

private String email;
private String racername;
private ArrayList<String> friendsList;
private ArrayList<String> vehicleList;
private ArrayList<String> trackList;



private double latPos;
private double longPos;



public User(String racername, String email){
    this.email = email;
    this.racername = racername;
    friendsList = new ArrayList<String>();
    vehicleList = new ArrayList<String>();
    trackList = new ArrayList<String>();
}

public User(){

}

public User(Parcel in){
    readFromParcel(in);
}

public static final Parcelable.Creator CREATOR = new Parcelable.Creator(){

    @Override
    public Object createFromParcel(Parcel source) {
        return new User(source);
    }

    @Override
    public Object[] newArray(int size) {
        return new User[size];
    }
};

public String getEmail(){
    return email;
}
public String getRacername(){
    return racername;
}
public ArrayList<String> getfriendsList(){
    return friendsList;
}
public ArrayList<String> getVehicleList(){
    return vehicleList;
}
public ArrayList<String> getTrackList() { return trackList; }
public double getLatPos(){
    return latPos;
}
public double getLongPos(){
    return longPos;
}


public String addFriend(String newFriend){
    String returnMessage = "";
    if(friendsList == null){
        friendsList = new ArrayList<String>();
        friendsList.add(newFriend);
    } else {
        if(friendsList.contains(newFriend)){
            returnMessage = "That friend already exists";
        } else {
            friendsList.add(newFriend);
            returnMessage = "Friend added!";
        }
    }
    return returnMessage;
}

public String deleteFriend(String oldFriend){
    String returnMessage = "";
    if(friendsList.contains(oldFriend)) {
        friendsList.remove(oldFriend);
        returnMessage = "Friend Removed";
    } else {
        returnMessage = "Friend not found.";
    }
    return returnMessage;
}

public void addTrack(String trackName){
    if(trackList==null){
        trackList = new ArrayList<String>();
    }
    trackList.add(trackName);
}


@Override
public int describeContents() {
    return 0;
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(email);
    dest.writeString(racername);
    dest.writeStringList(friendsList);
    dest.writeStringList(vehicleList);
    dest.writeStringList(trackList);

    dest.writeDouble(latPos);
    dest.writeDouble(longPos);


}

public void readFromParcel(Parcel in){
    email = in.readString();
    racername = in.readString();
    friendsList = in.createStringArrayList();
    vehicleList = in.createStringArrayList();
    trackList = in.createStringArrayList();


    latPos = in.readDouble();
    longPos = in.readDouble();

}
}

创建两个对象。将它们传递给意图并开始活动。用户对象是从先前的意图获得的，所以我不确定这是否给我错误。 HostRace是真的。

final Track newTrack;
            if(trackType.equals(Track.CIRCUIT)){
                newTrack = new 
Track(racername,trackName,Track.CIRCUIT,sumDistance);

            } else {
                newTrack = new Track(racername,trackName,Track.POINTTOPOINT,sumDistance);
            }
            newTrack.setCheckpoints(checkpoints);
            String trackKey = racername + "," + trackName;
            Log.d("Track key: ", trackKey);

            ssDB.child("tracks").child(trackKey).setValue(newTrack).addOnCompleteListener(new OnCompleteListener<Void>() {
                @Override
                public void onComplete(@NonNull Task<Void> task) {
                    if(task.isSuccessful()){
                        user.addTrack(trackName);
                        ssDB.child("users").child(user.getRacername()).child("trackList").setValue(user.getTrackList()).addOnCompleteListener(new OnCompleteListener<Void>() {
                            @Override
                            public void onComplete(@NonNull Task<Void> task) {
                                if(task.isSuccessful()){
                                    Toast.makeText(CreateTrackActivity2.this,"Track Created!",Toast.LENGTH_LONG).show();
                                    if(hostRace){

                                        intentToHostRaceActivity.putExtra("user",user);
                                        intentToHostRaceActivity.putExtra("track",newTrack);
                                        startActivity(intentToHostRaceActivity);
                                    } else {
                                        intentToHomeActivity.putExtra("user",user);
                                        startActivity(intentToHomeActivity);
                                    }
                                }
                            }
                        });


                    }
                }
            });

收到意图的另一个类的意图。

Track track = getIntent().getExtras().getParcelable("track");
User user = getIntent().getExtras().getParcelable("user");

我收到的例外

04-04 23:34:51.725 27284-27284/com.illbirdstudios.illbird.streetsend D/Exception:: java.lang.ClassCastException: com.illbirdstudios.illbird.streetsend.User cannot be cast to com.illbirdstudios.illbird.streetsend.Track

Answer 1

试试这个

public static final Parcelable.Creator CREATOR = new Parcelable.Creator(){

    @Override
    public Object createFromParcel(Parcel source) {
        return new Track(source);
    }

    @Override
    public Object[] newArray(int size) {
        return new Track[size];
    }
};

通过Parcelable获取错误的对象类型

1 个答案: