Question

我有一个保存音乐应用的类别和频道的单身人士。我使用单例，因为类别和通道是从嵌入在应用程序中的本地JSON文件加载的。但是，业务需求已更改，我现在从服务器上的远程JSON文件加载它们。

这里是ChannelLab类（大致）：

private ArrayList<Channel> mChannels;
private ArrayList<Category> mCategories;

// To be removed later...
private ArrayList<ChannelOld> mChannelsOld;
private static final int CHANNELS_OLD_JSON = R.raw.channels;
//

private static ChannelLab sChannelLab;
private Context mAppContext;

...


public ChannelLab(Context appContext) {
    sChannelLab = this;

    mAppContext = appContext;
    mChannels = new ArrayList<Channel>();
    mCategories = new ArrayList<Category>();

    //
    // To be removed later
    mChannelsOld = new ArrayList<ChannelOld>();
    //
    //
}

public static ChannelLab get(Context c) {
    if (sChannelLab == null) {
        //Crashlytics.log(1, TAG, "sChannelLab NULL");

        sChannelLab = new ChannelLab(c.getApplicationContext());
    }
    return sChannelLab;
}

public void loadAll() {
    try {
        //mChannels = loadChannels();
        new LoadChannelsFromServer().execute();

        //
        // To be removed later
        mChannelsOld = loadChannelsOld();
        //
        //
    } catch (Exception e) {
        mChannels = new ArrayList<Channel>();
        Log.e(TAG, "Error loading channels: ", e);
    }

    try {
        //mCategories = loadCategories();
        new LoadCategoriesFromServer().execute();
    } catch (Exception e) {
        mCategories = new ArrayList<Category>();
        Log.e(TAG, "Error loading categories: ", e);
    }
}

在发布时，我运行以下代码来加载类别和频道：

clab = new ChannelLab(getApplicationContext());
clab.setCallback(this);
clab.loadAll();

和mCategories和mChannels填充了类别和渠道。

问题是有时候（很可能是当活动被破坏时），ChannelLab实例仍然可用，mChannels和mCategories也是，但它们是空的。它们不是null，但它们的大小为0，并且在使用以下命令恢复行为并访问ChannelLab时会导致空指针异常：

ChannelLab(getActivity().getApplicationContext())

在没有活动时，我需要做些哪些更改才能确保mCategories和mChannels仍然填充数据？提前谢谢......

当Activites被破坏时，Singleton的ArrayList成员被清空

0 个答案: