显示ProgressDialog Android

Question

我有一个EditText，它从用户和一个searchButton中获取一个字符串。单击searchButton时，它将搜索XML文件并将其显示在ListView中。我能够从用户那里获取输入，搜索XML文件并在ListView中也显示usersearched值。我想要的是ProgressDialog在单击searchButton之后显示一个“请等待...正在检索数据...”之类的信息，然后在显示数据时将其关闭。public class Tab1Activity extends ListActivity {private Button okButton;private Button searchButton;Toast toast;String xml;private TextView searchText;private String searchTextString;HashMap<String, String> o;ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();@Overridepublic void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.tab1);    searchButton = (Button) findViewById(R.id.search_button);    searchButton.setOnClickListener(new View.OnClickListener() {        public void onClick(View v) {            // TODO Auto-generated method stub            System.out.print("hello");            searchText = (TextView) findViewById(R.id.search_text);            searchTextString = searchText.getText().toString();            readXml(searchTextString);        }    });}private void readXml(String searchTextString1) {    ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();    String xml = XMLfunctions.getXML();            //Here XMLfunctions is class name which parse xml    Document doc = XMLfunctions.XMLfromString(xml);    int numResults = XMLfunctions.numResults(doc);    if ((numResults <= 0)) {        Toast.makeText(Tab1Activity.this, "Testing xmlparser",                Toast.LENGTH_LONG).show();        finish();    }    NodeList nodes = doc.getElementsByTagName("result");    for (int i = 0; i < nodes.getLength(); i++) {        HashMap<String, String> map = new HashMap<String, String>();        Element e = (Element) nodes.item(i);        String nameMapString = XMLfunctions.getValue(e, "name");