将Android中的ArrayList<MyObject>作为可传递对象传递

Question

现在修改的代码反映了已接受的解决方案。

这现在作为一个工作示例，展示了如何将自定义ArrayList传递到DialogFragment中。

我正在使用Bundle在newInstance中传递自定义对象ArrayList到DialogFragment。ArrayList在newInstance中正确接收。调用putParcelable没有问题（没有错误），但是在Arraylist对象中的parcelable代码中设置或获取数据时未调用parcel方法。

我是否应该为ArrayList创建LocalityList类并使其可被设为parcelable，或者Locality类本身应该是parcelable的？

DialogFragment

/**
 * Create a new instance of ValidateUserEnteredLocationLocalitySelectorFragment, providing "localityList"
 * as an argument.
 */
public static ValidateUserEnteredLocationLocalitySelectorFragment newInstance(LocalityList localityList) {

    ValidateUserEnteredLocationLocalitySelectorFragment fragmentInstance = new ValidateUserEnteredLocationLocalitySelectorFragment();

    // Supply location input as an argument.
    Bundle bundle = new Bundle();
    bundle.putParcelable(KEY_LOCALITY_LIST, localityList);
    fragmentInstance.setArguments(bundle);

    return fragmentInstance;
}


/**
 * Retrieve the locality list from the bundle
 */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mLocalityList = getArguments().getParcelable(KEY_LOCALITY_LIST);
}


 @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.validate_user_entered_location, container, false);

    mLocalityListView = (ListView) view.findViewById(R.id.dialogLocalityListView);
    mAdapter = new SearchLocationLocalitiesListAdapter(getActivity(), mLocalityList);
    mLocalityListView.setAdapter(mAdapter);

    return view;
}

LocalityList类

import java.util.ArrayList;

import android.os.Parcel;
import android.os.Parcelable;

public class LocalityList extends ArrayList<Locality> implements Parcelable {

    private static final long serialVersionUID = 663585476779879096L;

    public LocalityList() {
    }

    @SuppressWarnings("unused")
    public LocalityList(Parcel in) {
        this();
        readFromParcel(in);
    }

    private void readFromParcel(Parcel in) {
        this.clear();

        // First we have to read the list size
        int size = in.readInt();

        for (int i = 0; i < size; i++) {
            Locality r = new Locality(in.readString(), in.readDouble(), in.readDouble());
            this.add(r);
        }
    }

    public int describeContents() {
        return 0;
    }

    public final Parcelable.Creator<LocalityList> CREATOR = new Parcelable.Creator<LocalityList>() {
        public LocalityList createFromParcel(Parcel in) {
            return new LocalityList(in);
        }

        public LocalityList[] newArray(int size) {
            return new LocalityList[size];
        }
    };

    public void writeToParcel(Parcel dest, int flags) {
        int size = this.size();

        // We have to write the list size, we need him recreating the list
        dest.writeInt(size);

        for (int i = 0; i < size; i++) {
            Locality r = this.get(i);

            dest.writeString(r.getDescription());
            dest.writeDouble(r.getLatitude());
            dest.writeDouble(r.getLongitude());
        }
    }
}

本地性类

import android.os.Parcel;
import android.os.Parcelable;


public class Locality implements Parcelable {

    private String mDescription;
    private double mLatitude;
    private double mLongitude;


    public Locality(String description, double latitude, double longitude) {
        super();
        this.mDescription = description;
        this.mLatitude = latitude;
        this.mLongitude = longitude;
    }

    public Locality(){
        super();
    }


    public String getDescription() {
        return mDescription;
    }

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


    public double getLatitude() {
        return mLatitude;
    }

    public void setLatitude(double latitude) {
        this.mLatitude = latitude;
    }


    public double getLongitude() {
        return mLongitude;
    }

    public void setLongitude(double longitude) {
        this.mLongitude = longitude;
    }


    @SuppressWarnings("unused")
    public Locality(Parcel in) {
        this();
        readFromParcel(in);
    }

    private void readFromParcel(Parcel in) {
        this.mDescription = in.readString();
        this.mLatitude = in.readDouble();
        this.mLongitude = in.readDouble();
    }

    public int describeContents() {
        return 0;
    }

    public final Parcelable.Creator<Locality> CREATOR = new Parcelable.Creator<Locality>() {
        public Locality createFromParcel(Parcel in) {
            return new Locality(in);
        }

        public Locality[] newArray(int size) {
            return new Locality[size];
        }
    };


    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(mDescription);
        dest.writeDouble(mLatitude);
        dest.writeDouble(mLongitude);
    }
}

- MartinS

Answer 1

我知道这个问题相当古老，但是既然我最初来这里寻找答案，我想分享我的经验。是的，您需要为 Locality 类实现 Parcelable 接口，但仅此而已。

如果您的 LocalityList 仅是一个 ArrayList 的包装器，则不需要它。

只需使用 putParcelableArrayList 方法即可。

ArrayList<Locality> localities = new ArrayList<Locality>;
...
Bundle bundle = new Bundle();
bundle.putParcelableArrayList(KEY_LOCALITY_LIST, localities);
fragmentInstance.setArguments(bundle);

return fragmentInstance;

并使用以下代码进行检索...

localities = savedInstanceState.getParcelableArrayList(KEY_LOCALITY_LIST);

因此，除非您出于其他原因需要自定义ArrayList，否则可以避免执行任何额外的工作，并仅为您的Locality类实现Parcelable。

- Caleb

Answer 2

是的，让 Locality 类本身成为 Parcelable，并且不要忘记进行 初始化。

ArrayList<Locality> mList= new ArrayList<Locality>();

- Mohammed Azharuddin Shaikh

---

谢谢。LocalityList和Locality类都需要是可包裹的吗，还是只需要Locality类本身就可以了？我原本以为我需要打包ArrayList并且这将序列化数组中的所有单个类。 - MartinS

是的，你必须在两个上实现Parcelable。而Serializable是为Java设计的（不建议在Android上使用），请始终使用Parcelable。 - Mohammed Azharuddin Shaikh

以上代码已被修改以实现已接受的解决方案。现在正常工作，如所示。这演示了如何将自定义ArrayList传递到FragmentDialog中以在ListView中显示。 - MartinS

Answer 3

我通常使用的技巧是使用谷歌的Gson将列表解析为Json。另一方面，我只需将字符串在Json中解析回新列表即可。

从未注意到任何滞后。

- blindado

---

更多的信息总是有益的（提供一个小的代码示例来说明）。目前你的回答感觉不像是对问题的回答。 - Styxxy

基本上这是我通常做的。List -> JSON字符串; Bundle; JSON字符串 -> List; - blindado