我似乎在我的应用程序中遇到一个奇怪的错误(参见GitHub),当我将对象传递给实现Parcelable的不同活动时会发生这种错误.

我已经在Stack Overflow上检查了其他问题和答案,但我无法找到解决方案.我已经尝试了答案here,例如 – 这里它是供参考：

-keepclassmembers class * implements android.os.Parcelable {

static ** CREATOR;

}

我还确保writeToParcel中的方法调用是有序的.关于此问题的Stack Overflow上的大多数其他问题都没有答案.

此外,我问一个新问题的原因是因为我认为我的问题是由于我在我的应用程序中使用接口的原因(稍后我将在这一点上进行扩展). Stack Overflow上的其他问题不适合我的特定情况.

在下面,我通过GitHub提供了代码的链接,以便您可以根据需要探索更多代码.

Process: com.satsuware.flashcards, PID: 4664

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.satsuware.flashcards/com.satsumasoftware.flashcards.ui.FlashCardActivity}: java.lang.RuntimeException: Parcel android.os.Parcel@d2219e4: Unmarshalling unknown type code 6815860 at offset 200

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)

...

Caused by: java.lang.RuntimeException: Parcel android.os.Parcel@d2219e4: Unmarshalling unknown type code 6815860 at offset 200

at android.os.Parcel.readValue(Parcel.java:2319)

at android.os.Parcel.readListInternal(Parcel.java:2633)

at android.os.Parcel.readArrayList(Parcel.java:1914)

at android.os.Parcel.readValue(Parcel.java:2264)

at android.os.Parcel.readArrayMapInternal(Parcel.java:2592)

at android.os.BaseBundle.unparcel(BaseBundle.java:221)

at android.os.Bundle.getParcelable(Bundle.java:786)

at android.content.Intent.getParcelableExtra(Intent.java:5377)

at com.satsumasoftware.flashcards.ui.FlashCardActivity.onCreate(FlashCardActivity.java:71)

at android.app.Activity.performCreate(Activity.java:6237)

at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)

...

我将上述活动称为(也是see GitHub)：

Intent intent = new Intent(TopicDetailActivity.this, FlashCardActivity.class);

intent.putExtra(FlashCardActivity.EXTRA_TOPIC, mTopic);

intent.putExtra(FlashCardActivity.EXTRA_NUM_CARDS, mSelectedNumCards);

intent.putExtra(FlashCardActivity.EXTRA_CARD_LIST, mFilteredCards);

startActivity(intent);

要考虑的主要部分是我通过mTopic.这是我创建的Topic interface.

但是,Topic接口扩展了Parcelable,因此实现Topic的对象还包括构造函数,CREATOR字段以及实现Parcelable的类通常必须具有的方法.

您可以通过GitHub链接查看相关的类,但我将在下面提供这些类的相关部分.这是Topic界面：

public interface Topic extends Parcelable {

int getId();

String getIdentifier();

String getName();

Course getCourse();

ArrayList getFlashCards(Context context);

class FlashCardsRetriever {

public static ArrayList filterStandardCards(ArrayList flashCards, @StandardFlashCard.ContentType int contentType) {

ArrayList filteredCards = new ArrayList<>();

for (FlashCard flashCard : flashCards) {

boolean isPaper2 = ((StandardFlashCard) flashCard).isPaper2();

boolean condition;

switch (contentType) {

case StandardFlashCard.PAPER_1:

condition = !isPaper2;

break;

case StandardFlashCard.PAPER_2:

condition = isPaper2;

break;

case StandardFlashCard.ALL:

condition = true;

break;

default:

throw new IllegalArgumentException("content type '" + contentType + "' is invalid");

}

if (condition) filteredCards.add(flashCard);

}

return filteredCards;

}

...

}

}

实现主题的类(对象)：

public class CourseTopic implements Topic {

...

public CourseTopic(int id, String identifier, String name, Course course) {

...

}

@Override

public int getId() {

return mId;

}

@Override

public String getIdentifier() {

return mIdentifier;

}

...

protected CourseTopic(Parcel in) {

mId = in.readInt();

mIdentifier = in.readString();

mName = in.readString();

mCourse = in.readParcelable(Course.class.getClassLoader());

}

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

@Override

public CourseTopic createFromParcel(Parcel in) {

return new CourseTopic(in);

}

@Override

public CourseTopic[] newArray(int size) {

return new CourseTopic[size];

}

};

@Override

public int describeContents() {

return 0;

}

@Override

public void writeToParcel(Parcel dest, int flags) {

dest.writeInt(mId);

dest.writeString(mIdentifier);

dest.writeString(mName);

dest.writeParcelable(mCourse, flags);

}

}

在上面代码的最后一行中,您可以看到我传递mCourse,这是我创建的Course对象.这里是：

public class Course implements Parcelable {

...

public Course(String subject, String examBoard, @FlashCard.CourseType String courseType,

String revisionGuide) {

...

}

public String getSubjectIdentifier() {

return mSubjectIdentifier;

}

public String getExamBoardIdentifier() {

return mBoardIdentifier;

}

public ArrayList getTopics(Context context) {

ArrayList topics = new ArrayList<>();

String filename = mSubjectIdentifier + "_" + mBoardIdentifier + "_topics.csv";

CsvParser parser = CsvUtils.getMyParser();

try {

List allRows = parser.parseAll(context.getAssets().open(filename));

for (String[] line : allRows) {

int id = Integer.parseInt(line[0]);

topics.add(new CourseTopic(id, line[1], line[2], this));

}

} catch (IOException e) {

e.printStackTrace();

}

return topics;

}

...

protected Course(Parcel in) {

mSubjectIdentifier = in.readString();

mBoardIdentifier = in.readString();

mCourseType = in.readString();

mRevisionGuide = in.readString();

}

public static final Creator CREATOR = new Creator() {

@Override

public Course createFromParcel(Parcel in) {

return new Course(in);

}

@Override

public Course[] newArray(int size) {

return new Course[size];

}

};

@Override

public int describeContents() {

return 0;

}

@Override

public void writeToParcel(Parcel dest, int flags) {

dest.writeString(mSubjectIdentifier);

dest.writeString(mBoardIdentifier);

dest.writeString(mCourseType);

dest.writeString(mRevisionGuide);

}

}

我怀疑这里可能会出现问题,这也是我的情景与其他问题不同的原因.

说实话,我不确定可能导致错误的原因,因此非常感谢答案中的解释和指导.

编辑：

在David Wasser的建议之后,我更新了部分代码,如下所示：

FlashCardActivity.java – onCreate(…)：

Bundle extras = getIntent().getExtras();

extras.setClassLoader(Topic.class.getClassLoader());

mTopic = extras.getParcelable(EXTRA_TOPIC);

Course.java – writeToParcel(…)：

dest.writeString(mSubjectIdentifier);

dest.writeString(mBoardIdentifier);

dest.writeString(mCourseType);

dest.writeInt(mRevisionGuide == null ? 0 : 1);

if (mRevisionGuide != null) dest.writeString(mRevisionGuide);

Course.java – 课程(包裹)：

mSubjectIdentifier = in.readString();

mBoardIdentifier = in.readString();

mCourseType = in.readString();

if (in.readInt() != 0) mRevisionGuide = in.readString();

我已经使用Log.d(…)添加了日志消息,以查看在writeToParcel(…)中传递时是否有任何变量为null,并使用David Wasser的方法来正确处理此问题.

但是,我仍然得到相同的错误消息.