以下是我的三個活動,問題是我在LineGraph中將Xstring的輸出變爲null。當調試它,它示出了這樣的模式:AsyncTask的doInBackground在我調用它後不能正常工作
parseStrings = mJsoupAct.getOutput(); LineGraph.java
mExecute(); jsoupAct.java
new Parsee()。execute(); jsoupAct.java
Log.d(「xoutputD」,output +「」); jsoupAct.java
url =「http://www.google.co.in/」; jsoupAct.java ...........
現在的問題是。爲什麼4號線5日前執行。由於執行此操作,它返回null,然後執行doInBackground。爲什麼發生這種情況?
MainActivity
public class MainActivity extends Activity {
jsoupAct mJsoupAct = new jsoupAct();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d("xmain", "main");
Intent i = new Intent(getApplicationContext(), LineGraph.class);
startActivity(i);
}
}
LineGraph
public class LineGraph extends Activity {
String parseStrings;
jsoupAct mJsoupAct;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mJsoupAct = new jsoupAct();
Xparse();
}
public void Xparse() {
parseStrings = mJsoupAct.getOutput();
Log.d("xstring", parseStrings + "");
}
}
jsoupAct
public class jsoupAct extends Activity {
public String output;
public String url;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public void mExecute() {
new Parsee().execute();
}
public class Parsee extends AsyncTask<String, String, String> {
protected String doInBackground(String... params) {
try {
url = "http://www.google.co.in/";
Document doc = Jsoup.connect(url).get();
String body = doc.body().text();
output = body.toString();
Log.d("xoutputD0", output + "");
} catch (IOException e) {
e.printStackTrace();
}
return output;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(output);
Log.d("xoutputD1", output + "");
}
}
public String getOutput() {
mExecute();
Log.d("xoutputD", output + "");
return output;
}
public void setOutput(String output) {
this.output = output;
}
}