我正在尝试使用Volley，recycleView和SwipeRefreshLayout进行示例，如下代码所示。我现在面临的问题是，当我向下滑动时，出现SwipeRefresh图标，并且日志记录器显示以下结果：
W/ActMain: POST.Runnable_1
W/ActMain: <fetchJSONObjectRequest.....>
D/ActMain: <fetchJSONObjectRequest> mProductsList.size: 0
由于mProductsList.size = 0，这意味着方法fetchJSONObjectRequest（）不会等到http请求完成以获取json数据对象。我打算做的是，当我向下滑动时，应获取JSON数据对象，并应填充recycleView。
我如何找出为什么在滑动布局时不等到fetchJSONObjectRequest（）完成？我应该使用AsyncTask吗？
代码
this.mSwipeToRefresh.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
TextView tv = (TextView) findViewById(R.id.actMainTextViewTest);
tv.setText("REFRESHED");
mRecycleView = (RecyclerView) findViewById(R.id.actMainRecyclerView);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getApplicationContext());
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecycleView.setLayoutManager(linearLayoutManager);
this.mSwipeToRefresh.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
TextView tv = (TextView) findViewById(R.id.actMainTextViewTest);
tv.setText("REFRESHED");
mRecycleView = (RecyclerView) findViewById(R.id.actMainRecyclerView);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getApplicationContext());
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecycleView.setLayoutManager(linearLayoutManager);
new FetchJSONAsync().execute();
}
});
}
}
private class FetchJSONAsync extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
mSwipeToRefresh.setRefreshing(true);
}
@Override
protected Void doInBackground(Void... params) {
fetchJSONObjectRequest();
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
mSwipeToRefresh.setRefreshing(false);
Log.d(TAG, "onPostExecute: mProductsList.size(): " + mProductsList.size());
}
}
fetchJSONObjectRequest ：
private List<Products> fetchJSONObjectRequest() {
Log.w(TAG, "<fetchJSONObjectRequest.....>");
this.mJSONObjectRequest = new JsonObjectRequest(Request.Method.GET, this.BASE_URL, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Log.w(TAG, "<onResponse> response: " + response);
Iterator<String> JSONObjectKeys = response.keys();
String key = null;
try {
while (JSONObjectKeys.hasNext()) {
key = JSONObjectKeys.next();
Log.d(TAG, "<onResponse> key: " + key);
if (key.equals(NAME_JSON_ARRAY_PRODUCTS) && getTypeOfJSONObjectForKey(response.get(key)).equals(TYPE_JSON_ARRAY)) {
this.parseDataFromJSONArray(response.getJSONArray(key));
break;
}
}
this.assignEntriesToModel();
} catch (JSONException e) {
e.printStackTrace();
}
mSwipeToRefresh.setRefreshing(false);
}
private void assignEntriesToModel() {
Log.w(TAG, "<assignEntriesToModel>");
for (int i = 0; i < mJSONObjectEntriesList.size(); i++) {
String name = String.valueOf(mJSONObjectEntriesList.get(i)[0]);
Long releaseDate = Long.valueOf(mJSONObjectEntriesList.get(i)[1].toString());
Boolean isAvailable = Boolean.valueOf(mJSONObjectEntriesList.get(i)[2].toString());
String description = String.valueOf(mJSONObjectEntriesList.get(i)[3]);
String imageURL = String.valueOf(mJSONObjectEntriesList.get(i)[4]);
JSONObject price = (JSONObject) mJSONObjectEntriesList.get(i)[5];
Float priceValue = Float.valueOf(mJSONObjectEntriesList.get(i)[6].toString());
String priceCurrency = String.valueOf(mJSONObjectEntriesList.get(i)[7]);
String rating = String.valueOf(mJSONObjectEntriesList.get(i)[8]);
mProductsList.add(new Products(name, releaseDate, isAvailable, description, imageURL, priceValue,
priceCurrency, rating));
}
Log.d(TAG, "mProductsList.size: " + mProductsList.size());
}
private void parseDataFromJSONArray(JSONArray jsonArray) throws JSONException {
Log.w(TAG, "<parseDataFromJSONArray> jsonArray: " + jsonArray);
for (int i = 0; i < jsonArray.length(); i++) {
Log.d(TAG, "+++++++++++++++++++++++++++++++++++Beginning Of Iteration " + i + " +++++++++++++++++++++++++++++++++++++++++++");
jsonObject = this.getObjectsFromJSONArrayForIndex(jsonArray, i);
mJSONObjectEntriesList.add(this.getEntriesFromJSONObject(jsonObject));
Log.d(TAG, "number of entries in list: " + mJSONObjectEntriesList.size());
Log.d(TAG, "+++++++++++++++++++++++++++++++++++Eno Of Iteration " + i + "+++++++++++++++++++++++++++++++++++++++++++");
}
}
private Object[] getEntriesFromJSONObject(JSONObject jsonObject) throws JSONException {
Object[] jsonObjectsArray = new Object[9];
namePropertyValue = jsonObject.get(JSON_PROP_IN_ARRAY_NAME);
releaseDatePropertyValue = jsonObject.get(JSON_PROP_IN_ARRAY_RELEASE_DATE);
availablePropertyValue = jsonObject.get(JSON_PROP_IN_ARRAY_AVAILABLE);
descriptionPropertyValue = jsonObject.get(JSON_PROP_IN_ARRAY_DESCR);
imageURLPropertyValue = jsonObject.get(JSON_PROP_IN_ARRAY_IMAGE_URL);
pricePropertyValue = jsonObject.get(JSON_PROP_IN_ARRAY_PRICE);
valuePropertyValue = jsonObject.getJSONObject(JSON_PROP_IN_ARRAY_PRICE).get(JSON_PROP_IN_ARRAY_PRICE_OBJ_VALUE);
currencyPropertyValue = jsonObject.getJSONObject(JSON_PROP_IN_ARRAY_PRICE).get(JSON_PROP_IN_ARRAY_PRICE_OBJ_CURRENCY);
ratingPropertyValue = jsonObject.get(JSON_PROP_IN_ARRAY_RATING);
jsonObjectsArray[0] = namePropertyValue;
jsonObjectsArray[1] = releaseDatePropertyValue;
jsonObjectsArray[2] = availablePropertyValue;
jsonObjectsArray[3] = descriptionPropertyValue;
jsonObjectsArray[4] = imageURLPropertyValue;
jsonObjectsArray[5] = pricePropertyValue;
jsonObjectsArray[6] = valuePropertyValue;
jsonObjectsArray[7] = currencyPropertyValue;
jsonObjectsArray[8] = ratingPropertyValue;
Log.v(TAG, "<getEntriesFromJSONObject> name: " + namePropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> releaseDate: " + releaseDatePropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> available: " + availablePropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> description: " + descriptionPropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> imageURL: " + imageURLPropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> price: " + pricePropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> value: " + valuePropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> currency: " + currencyPropertyValue);
Log.v(TAG, "<getEntriesFromJSONObject> rating: " + ratingPropertyValue);
return jsonObjectsArray;
}
private JSONObject getObjectsFromJSONArrayForIndex(JSONArray jsonArray, int index) throws JSONException {
return jsonArray.getJSONObject(index);
}
private String getTypeOfJSONObjectForKey(Object data) throws JSONException {
Object json = new JSONTokener(data.toString()).nextValue();
if (json instanceof JSONArray) {
Log.d(TAG, "<getTypeOfJSONObjectForKey> JSON_TYPE: " + TYPE_JSON_ARRAY);
return TYPE_JSON_ARRAY;
} else {
Log.i(TAG, "<getTypeOfJSONObjectForKey> JSON_TYPE: " + TYPE_JSON_ARRAY);
return TYPE_JSON_OBJECT;
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
mSwipeToRefresh.setRefreshing(false);
}
});
Log.d(TAG, "<fetchJSONObjectRequest> mProductsList.size: " + mProductsList.size());
this.mRequestQueue.add(this.mJSONObjectRequest);
return mProductsList;
}