我有一個異步任務： package e.marco.swimcommit;import android.os.AsyncTask;import org.jsoup.Jsoup;import org.jsoup.nodes.Document;import org.jsoup.nodes.Element;import org.jsoup.select.Elements;import java.io.IOException;public class News extends AsyncTask<String, Void, String> { @Override protected String doInBackground(String... strings) { final StringBuilder builder = new StringBuilder(); final StringBuilder builder2 = new StringBuilder(); { try { Document doc = Jsoup.connect("http://www.schwimmclub-schwandorf.de/index.php/8-home/56-infos-neuigkeiten").get(); String title = doc.title(); Elements links = doc.select("h2"); Elements links2 = doc.select("h3"); builder.append(title).append("\n"); for (Element link : links) { builder.append(link.text()).append("$"); } for (Element link : links2) { builder2.append(link.text()).append("$"); } } catch (IOException e) { e.printStackTrace(); } } String text = builder.toString() + "%" + builder2.toString(); return text; }}和我的 MainActivity 中的 onResume Methode 將返回的文本設置在文本視圖中 @Override protected void onResume() { super.onResume(); try { eins.setText(new News().execute().get()); } catch (ExecutionException e) { e.printStackTrace(); } catch (InterruptedException e) { e.printStackTrace(); } }但是，如果我啟動應用程序，它會顯示一個白屏，直到 onResume Methode 獲取文本并將其設置為 Textview。如何在沒有延遲啟動的情況下加載應用程序顯示所有其他元素，如按鈕背景等？以便在 onResume Methode 獲取信息并設置之前 Textview 是空白的？編輯：不阻塞用戶界面
3 回答
墨色風雨
TA貢獻1853條經驗 獲得超6個贊
AsyncTask 用于執行后臺操作并在 UI 線程上發布結果。在您的情況下，您應該放入eins.setTextAsyncTask onPostExecute。
另一個問題是因為 AsyncTask 是一個單獨的類，所以您需要定義一個接口將結果傳遞回 MainActivity。
消息
public class News extends AsyncTask<String, Void, String> {
private WeakReference<OnNewsListener> mOnNewsListener;
public void setOnNewsListener(OnNewsListener listener) {
mOnNewsListener = new WeakReference<>(listener);
}
@Override
protected String doInBackground(String... strings) {
final StringBuilder builder = new StringBuilder();
final StringBuilder builder2 = new StringBuilder();
{
try {
Document doc = Jsoup.connect("http://www.schwimmclub-schwandorf.de/index.php/8-home/56-infos-neuigkeiten").get();
String title = doc.title();
Elements links = doc.select("h2");
Elements links2 = doc.select("h3");
builder.append(title).append("\n");
for (Element link : links) {
builder.append(link.text()).append("$");
}
for (Element link : links2) {
builder2.append(link.text()).append("$");
}
} catch (IOException e) {
e.printStackTrace();
}
}
String text = builder.toString() + "%" + builder2.toString();
return text;
}
@Override
protected void onPostExecute(String text) {
if (mOnNewsListener != null) {
if (mOnNewsListener.get() != null) {
mOnNewsListener.get().onNews(text);
}
}
}
public interface OnNewsListener {
void onNews(String text);
}
}
主要活動
public class MainActivity extends AppCompatActivity implements News.OnNewsListener{
TextView eins;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
eins = findViewById(R.id.eins);
}
@Override
protected void onResume() {
super.onResume();
News news = new News();
news.setOnNewsListener(this);
news.execute();
}
@Override
public void onNews(String text) {
eins.setText(text);
}
}
ibeautiful
TA貢獻1993條經驗 獲得超6個贊
根據pz64的建議，在方法中設置文本onPostExecute()并調用AsyncTask()不調用get()方法。get()AsyncTask 上的方法使任務同步并影響您的 UI。
public class News extends AsyncTask<String, Void, String> {
@override
protected void onPreExecute(){
//initiate your loading views
}
@Override
protected String doInBackground(String... strings) {
final StringBuilder builder = new StringBuilder();
final StringBuilder builder2 = new StringBuilder();
{
try {
Document doc = Jsoup.connect("http://www.schwimmclub-schwandorf.de/index.php/8-home/56-infos-neuigkeiten").get();
String title = doc.title();
Elements links = doc.select("h2");
Elements links2 = doc.select("h3");
builder.append(title).append("\n");
for (Element link : links) {
builder.append(link.text()).append("$");
}
for (Element link : links2) {
builder2.append(link.text()).append("$");
}
} catch (IOException e) {
e.printStackTrace();
}
}
String text = builder.toString() + "%" + builder2.toString();
return text;
}
@override
protected void onPostExecute(String response){
//dispose loading views
if(response != null){
eins.setText(response);
}else{
//could not load
}
}
}
稱呼：
@Override
protected void onResume()
{
super.onResume();
new News().execute(); //do not call get method
}
忽然笑
TA貢獻1806條經驗 獲得超5個贊
您可以在 oncreate 方法中調用 asyncTask。并在 onProgressUpdate 方法中設置結果。
@Override
protected void onProgressUpdate(String... text) {
eins.setText.setText(text);
}
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