【发布时间】：2015-12-18 13:28:18
【问题描述】：
我正在尝试向我的应用程序添加一个进度对话框，同时它会从 volley 加载数据。我尝试了几种方法，但我目前正在关注本教程http://www.androidhive.info/2014/07/android-custom-listview-with-image-and-text-using-volley/，并希望它看起来像那里使用的示例。到目前为止，请有人看看我的代码！我没有收到错误，但它不像示例那样显示。如您所见，我在 onCreate 中创建了该方法，并在我的响应侦听器中调用了 hide 方法。
谢谢！
MainActivity.java
public class MainActivity extends AppCompatActivity {
private List<NewsRecord> newsListData = new ArrayList<NewsRecord>();
private GridView newsListView;
private NewsListAdapter adapter;
LinearLayout layout;
private ProgressDialog pDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GridView newsListView = (GridView) findViewById(R.id.newsFeedList);
adapter = new NewsListAdapter(this, R.layout.adapter_news_list, newsListData, this);
layout = (LinearLayout) findViewById(R.id.progressbar_view);
newsListView.setAdapter(adapter);
pDialog = new ProgressDialog(this);
// Showing progress dialog before making http request
pDialog.setMessage("Loading Articles...");
pDialog.show();
newsListView.setOnItemClickListener(itemClicked);
nextStart = 0;
updateListData(nextStart, 20);
}
public int nextStart = 0;
public void updateListData(int StartPoint, int count){
String url = "http://www.efstratiou.info/projects/newsfeed/getList.php?start=" + StartPoint + "&count=" + count;
EDANewsApp app = EDANewsApp.getInstance();
JsonArrayRequest jsonRequest = new JsonArrayRequest(url, listener, errorListener);
app.requestQueue.add(jsonRequest);
nextStart +=count;
}
@Override
public boolean onCreateOptionsMenu (Menu menu){
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main_menu, menu);
return true;
}
@Override
public void onDestroy() {
super.onDestroy();
hidePDialog();
}
private void hidePDialog() {
if (pDialog != null) {
pDialog.dismiss();
pDialog = null;
}
}
public boolean onOptionsItemSelected(MenuItem item){
switch (item.getItemId()) {
case R.id.action_about:
Intent intent = new Intent(this, AboutActivity.class);
startActivity(intent);
return true;
case R.id.action_search:
return true;
case R.id.action_settings:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
AdapterView.OnItemClickListener itemClicked = new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent intent = new Intent(MainActivity.this, NewsItemActivity.class);
intent.putExtra("newsItemId", newsListData.get(position).recordId);
startActivity(intent);
}
};
private SearchView.OnQueryTextListener searchQueryListener = new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String query) {
Intent searchIntent = new Intent(MainActivity.this, SearchResultsActivity.class);
searchIntent.putExtra("query", query);
return true;
}
@Override
public boolean onQueryTextChange(String newText) {
return false;
}
};
//Listeners
Response.Listener<JSONArray> listener = new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
//we successfully received the JSONArray
//Here we will extract the data and use it in our app
//Clear the dataset before loading new data
// newsListData.clear();
//Go through all the JSON objects
for (int i = 0; i < response.length(); i++) {
try {
//Get one JSON object
JSONObject jsonObj = response.getJSONObject(i);
//Put JSON data in a Java object
NewsRecord record = new NewsRecord();
record.recordId = jsonObj.getInt("record_id");
record.title = jsonObj.getString("title");
record.date = jsonObj.getString("date");
record.shortInfo = jsonObj.getString("short_info");
record.imageUrl = jsonObj.getString("image_url");
newsListData.add(record);
} catch (JSONException e) {
e.printStackTrace();
}
}
adapter.notifyDataSetChanged();
hidePDialog();
}
};
Response.ErrorListener errorListener = new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
//There was an error in the communication
//We can notify the user about it
hidePDialog();
}
};
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/newsListItem"
android:layout_width="match_parent"
android:layout_height="wrap_content"
tools:context=".MainActivity">
<LinearLayout
android:id="@+id/progressbar_view"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:orientation="vertical" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:orientation="horizontal" >
<ProgressBar
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical|center_horizontal" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical|center_horizontal"
android:text="Loading data..." />
</LinearLayout>
<View
android:layout_width="fill_parent"
android:layout_height="1dp"
android:background="#C0C0C0" />
</LinearLayout>
<GridView
android:id="@+id/newsFeedList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:verticalSpacing="0dp"
android:horizontalSpacing="0dp"
android:stretchMode="columnWidth"
android:numColumns="2"/>
</FrameLayout>
【问题讨论】：
-
介绍一下 AsyncTask。在该任务中，您可以显示一个进度对话框。在 google 中搜索 AsyncTask 和 Progress Dialog。第一个命中就是你所需要的
-
有人告诉我不需要使用 AsyncTask，只需在提交请求之前显示进度条，并在所有数据到达时将其隐藏在 onResponse() 中
标签： java android xml android-volley