java - 在 Android 中使用 JSON 数据的 ContentAdapter

Question

我正在开发的 Android 应用程序具有使用 fragment 的选项卡导航

我的 fragment Activity/ View 中有一个 ContentAdapter，它使用 res/values/arrays.xml 中的数据(如下所示)来呈现选项卡内容

res/values/arrays.xml

<resources>
  <string-array name="names">
    <item>an item A</item>
    <item>an item B</item>
  </string-array>
  <string-array name="descs">
    <item>this is desc for item A</item>
    <item>this is desc for item B</item>
  </string-array>
</resources>

java/my.app.namespace/MyFragmentList.java 适配器

public static class ContentAdapter extends RecyclerView.Adapter<ViewHolder> {
    // Set numbers of List in RecyclerView.
    private static final int LENGTH = 18;

    private final String[] mDesc;
    private final String[] mName;

    public ContentAdapter(Context context) {

        Resources resources = context.getResources();
        mDesc = resources.getStringArray(R.array.descs);
        mName = resources.getStringArray(R.array.names);

        a.recycle();
    }

我可以看到，在 public ContentAdapter() 内部，资源文件被调用，并且值被设置为稍后在 public void onBindViewHolder(ViewHolderholder, intposition) 中访问，它呈现 xml 中的每个项目。

我想访问公共(public) ContentAdapter(上下文上下文)内的外部 JSON URL 并从那里设置数组值。

public ContentAdapter(Context context) {

        //Resources resources = context.getResources();
        //mDesc = resources.getStringArray(R.array.descs);
        //mName = resources.getStringArray(R.array.names);

        //get JSON URL Data (ASYNC?)
        mName = set name from json;
        //...

        a.recycle();
    }

不确定此时在应用程序中获取 JSON 的最佳方法是什么。我是在加载 MainActivity 之前下载 JSON 还是此时进行 JSON 获取？

Answer 1

正如我在评论中提到的:

You should not load data inside adapter, first you should load/fetch in your respective activity/fragment and pass reference to adapter. So First fetch your json data in activity, parse it there and than pass the result list to adapter.

您应该遵循以下方法:

在您的 Activity 中:

private class GetContentTask extends AsyncTask<Void, Void, JSONObject> {

    public GetContentTask() {
    }

    @Override
    protected JSONObject doInBackground(Void... voids) {
        // fetch JSON from api
       JSONObject jsonObject = new JSONObject();
        //you can pass string or json object whatever is preferred
        return jsonObject;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        //show progress
    }

    @Override
    protected void onPostExecute(final JSONObject result) {
        super.onPostExecute(result);
        //hide progress
        ArrayList<String> mDesc; // parse array from result
        ArrayList<String> mName; // parse array from result

        //set your adapter
        ContentAdapter adapter = new ContentAdapter(context,mDesc,mName);

        //or call your method and pass data in it
        setupViewPager(viewPager,mDesc,mName);
    }
}

您的适配器类:

public class ContentAdapter extends RecyclerView.Adapter<ViewHolder> {

    private final ArrayList<String> mDesc;
    private final ArrayList<String> mName;

    public ContentAdapter(Context context,ArrayList<String> mDesc,ArrayList<String> mName) {
        this.mDesc = mDesc;
        this.mName = mName;
    }
}

希望这会有所帮助。