我正在使用Firebase將數據顯示到文本視圖中。我使用asynctask在加載時在後臺加載數據,我想在數據加載到我的文本視圖之前顯示加載消息。 (即doinBackground
方法完成後立即生效),並且用戶只會在Firebase數據加載一段時間後纔看到空文字視圖。如何在從Firebase數據庫提取數據時顯示加載消息?
如何防止這種情況,並顯示進程對話框,直到我的textview獲取加載Firebase數據?
here is my code
<pre>
<code>
public class LastPage extends AppCompatActivity {
TextView title, author, article;
DatabaseReference mDatabase;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_last_page);
title = (TextView) findViewById(R.id.last_page_title);
author = (TextView) findViewById(R.id.last_page_author);
article = (TextView) findViewById(R.id.last_page_article);
mDatabase = FirebaseDatabase.getInstance().getReference();
new LoadFirebaseData().execute();
}
private class LoadFirebaseData extends AsyncTask<Void, Void, Integer>
{
private ProgressDialog Dialog = new ProgressDialog(LastPage.this);
@Override
protected void onPreExecute()
{
try {
Dialog.setMessage("Doing something...");
Dialog.show();
}catch (Exception e)
{
e.printStackTrace();
}
}
@Override
protected void onPostExecute(Integer result)
{
if(result==0)
{
//do some thing
}
// after completed finished the progressbar
Dialog.dismiss();
}
@Override
protected Integer doInBackground(Void... params) {
mDatabase.child("version_1_5").child("title").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String temp = dataSnapshot.getValue(String.class);
title.setText(temp);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
mDatabase.child("version_1_5").child("author").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String temp = dataSnapshot.getValue(String.class);
author.setText(temp);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
mDatabase.child("version_1_5").child("article").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String temp = dataSnapshot.getValue(String.class);
article.setText(temp);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
return 0;
}
}
}
</code>
</pre>
JSON樹結構:
Root
Version_1_5
Title:TitleValue
Author:AuthorValue
Article:ArticleValue
請分享您的JSON樹 –
在我的JSON樹它有3周的childNodes像這根/ version_1_5 /標題:valueOfTitle,根/ version_1_5/aticle:valueOfArticle,根/ version_1_5 /作者:valueOfAuthor –