Question

如何通过Bundle of Activity传递Parcelable，一个List类型的对象？不断产生错误类型NPE，在OnCreateView中准备Parcelable。

// Fragment object в Activity
public Fragment systemFragList(){
          a = new AppsManagerFragment();
          b = new Bundle();
          dApps = new DataApps(this);
          //transmission through List the designer
          listCreater = new MakingListObject(dApps.getSystemAppsList()); 
          b.putParcelable("List", listCreater); // transfer Parcelable object through Bundle
          a.setArguments(b);

        return a;
    };

// Parcelable class
public class MakingListObject implements Parcelable {

    private List<ApplicationInfo> list;

 // get an object List <ApplicationInfo> constructor
    public MakingListObject(List<ApplicationInfo> l) { 
        this.list = l;
    }
    public MakingListObject(Parcel in) {
        in.readTypedList(list, ApplicationInfo.CREATOR); // read
    }
    public List<ApplicationInfo> getList(){ // vethod return list
        return list;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) { // write
       dest.writeTypedList(list);
    }
    @Override
    public int describeContents() {
        return 0;
    }

   CREATOR...
}

//Admission List to the Fragment in onCreateView()    
MakingListObject obj = (MakingListObject)this.getArguments().getParcelable("List"); // NPE ERROR
List<ApplicationInfo> listData = obj.getList();

Answer 1

您必须先启动列表。

public MakingListObject(Parcel in) {
    list = new ArrayList<ApplicationInfo>;
    in.readTypedList(list, ApplicationInfo.CREATOR); // read
}

Answer 2

使用

存储Parcelable的列表

Bundle dataToSend = new Bundle(); ArrayList<? super Parcelable> list = new ArrayList<>(); //add items here .... dataToSend.putParcelableArrayList("foo", list);

并使用

阅读

Bundle receivedData = ... receivedData.getParcelableArrayList("foo")

希望这会有所帮助

通过一系列活动通过Parcelable List <！ - ？ - >

2 个答案: