我对安卓很陌生。我有两个活动 A, B 。活动 A 解析来自服务器的数据并遍历各个级别。并通过意图调用活动B。活动 B 需要一些时间来显示数据，所以我试图显示进度条。这是我的代码。
public class Display extends Activity {
ProgressDialog dialog;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.attributequestions);
new asynctask().execute();
}
class asynctask extends AsyncTask<Context,Void,Void>{
Survey[] surveyque=null;
// i hace created seperated class forsurvey that has info about data
String list[];
private ProgressDialog Dialog;
@Override
protected void onPreExecute()
{
Dialog=ProgressDialog.show(Display.this, "Parsing Data", "Please wait..........");
}
@Override
protected void onPostExecute(Void unused)
{
try
{
if(Dialog.isShowing())
{
Dialog.dismiss();
}
Intent intent=getIntent();
}
catch(Exception e)
{
Log.d("Onsitev4", "error");
}
}
@Override
protected Void doInBackground(Context... params) {
try {
LinearLayout layout1 = (LinearLayout) findViewById(R.id.linearLayout1);
//getting exception here. I dont understant why
// I have declared layout params and displaying activities in another class
ButtonView c = new ButtonView();
c.layout=layout1;
c.context =getBaseContext();
DbCoreSqlSurveys surveys=new DbCoreSqlSurveys(getBaseContext());
Document doc =surveys.getSurveySet();
surveyquestions= GetSurveyLevels(doc,c );
} catch (TransformerFactoryConfigurationError e) {
e.printStackTrace();
}
return null;
}
}
public SurveyObject[] GetSurveyLevels(Document doc, ButtonView c) {
NodeList nlQuestions = doc.getElementsByTagName("Survey");
SurveyObject[] allsurveys = new SurveyObject[nlQuestions.getLength()];
for (int i = 0; i < nlQuestions.getLength(); i++){
Node survey = nlQuestions.item(i);
String f =survey.getNodeName();
Log.d("OnsiteV4", "survey " + f);
NodeList surveyChildNodes = survey.getChildNodes();
SurveyObject s=new SurveyObject();
for (int j = 0; j < surveyChildNodes.getLength(); j++){
Node surveyChild = surveyChildNodes.item(j);
String h =surveyChild.getNodeName();
Log.d("OnsiteV4", "survey child node = " + h);
if (h !="#text"){
Surveys t = Surveys.valueOf(h);
switch(t){
case KeySurvey:
s.KeySurvey=surveyChild.getTextContent();
displaySurveyLink(s.SurveyDescription,"",c,0,s.SurveyDescription,"","","","");
break;
case SurveyDescription:
s.SurveyDescription=surveyChild.getTextContent();
displaySurveyLink(s.SurveyDescription,"",c,0,s.SurveyDescription,"","","","");
break;
case SurveyUserCode:
s.SurveyUserCode=surveyChild.getTextContent();
break;
case Level1:
if(surveyChild.hasChildNodes()){
s.Level1= processLevel1Nodes(surveyChild,c,s.SurveyDescription);
}
break;
default:
break;
}
}
allsurveys[i]=s;
}
}
return allsurveys;
}
// methods iterating through levels that is not showed
private void displaySurveyLink(final String description, String tag, ButtonView c, int indentation, final String surveyDescription, final String level1description, final String level2description, final String level3description, final String level4description)
{
if (description == null || tag == null){
return;
}
final TextView tv = c.addButton(description,tag,indentation);
tv.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
final Intent intent = new Intent();
intent.setClass(v.getContext(),ActivityB.class);
intent.putExtra("KeyLevel",tv.getTag().toString());
intent.putExtra("SurveyDescription",surveyDescription);
intent.putExtra("level1description",level1description);
intent.putExtra("level2description",level2description);
intent.putExtra("level3description",level3description);
intent.putExtra("level4description",level4description);
intent.putExtra("Description",description);
if (tv.getTag() != null){
if (tv.getTag().toString() != ""){
startActivity(intent);
}
}
}
});
}
}
我在 doinbackground 中遇到异常。我很困惑 。请帮我..