我尝试在应用程序顶部添加进度微调器，同时从排球中接收数据。可能有一种更简单的方法可以做到这一点，但这是我迄今为止尝试的只有一些错误。第一个错误是newsListView得到的错误变化是从内部类中访问的，需要被声明为final＆＃39;。并且无法解析字符串值。这是我在oncreate方法中创建的类：
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
hidePDialog();
//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();
}
};
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();
}
};
}
，进度条出现在activity_main.xml中，如下所示：
<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>
答案 0 :(得分：3)
以下是我经常在项目中使用的方式，IMO你可以看看并申请你的项目，希望它有所帮助！
@Override
protected void onCreate(Bundle savedInstanceState) {
...
mRequestQueue = Volley.newRequestQueue(this);
mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
mProgressBar.setVisibility(View.VISIBLE);
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.GET, url, null, new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
mProgressBar.setVisibility(View.INVISIBLE);
// do something...
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
mProgressBar.setVisibility(View.INVISIBLE);
// do something...
}
});
mRequestQueue.add(jsonArrayRequest);
...
}
答案 1 :(得分：1)
您声明了进度条
private ProgressDialog pDialog;
pDialog = new ProgressDialog(this);
// Showing progress dialog before making http request
pDialog.setMessage("Loading...");
pDialog.show();
你称之为Volley请求，而不是当你得到响应（成功或错误事件）时，你调用hidePDialog方法
hidePDialog();
//method to hide progressbar
private void hidePDialog() {
if (pDialog != null) {
pDialog.dismiss();
pDialog = null;
}
}
答案 2 :(得分：0)
@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);
newsListView.setOnItemClickListener(itemClicked);
EDANewsApp app = EDANewsApp.getInstance();
nextStart = 0;
updateListData(nextStart, 20);
}
private class Task extends AsyncTask<String, Integer, Boolean> {
private ProgressDialog dialog;
@Override
protected void onPreExecute() {
dialog.setMessage("Doing something, please wait.");
dialog.show();
layout.setVisibility(View.VISIBLE);
newsListView.setVisibility(View.GONE);
super.onPreExecute();
}
@Override
protected void onPostExecute(Boolean result) {
dialog.dismiss();
layout.setVisibility(View.GONE);
newsListView.setVisibility(View.VISIBLE);
adapter.notifyDataSetChanged();
super.onPostExecute(result);
}
@Override
protected Boolean doInBackground(String... params) {
stringValues.add("String 1");
stringValues.add("String 2");
stringValues.add("String 3");
stringValues.add("String 4");
stringValues.add("String 5");
try {
Thread.sleep(3000);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
希望这会对你有所帮助。