public class StartActivity extends Activity {
public static Context appContext;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
appContext = getApplicationContext();
//ActionBar
ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
Tab tab = actionBar.newTab().setText("First tab")
.setTabListener(new MyTabListener<AFragment>(this, "artist", AFragment.class));
actionBar.addTab(tab);
tab = actionBar.newTab().setText("Second Tab")
.setTabListener(new MyTabListener<BFragment>(this, "album", BFragment.class));
actionBar.addTab(tab);
try {
// get exchange rate from xml
DownloadXMLFile download = new DownloadXMLFile();
download.execute(new URL("http://vietcombank.com.vn/ExchangeRates/ExrateXML.aspx"));
} catch (Exception e) {
System.out.println(">>>> EXCEPTION: " + e.getMessage());
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.menuitem_search:
Toast.makeText(appContext, "search", Toast.LENGTH_SHORT).show();
return true;
case R.id.menuitem_add:
Toast.makeText(appContext, "add", Toast.LENGTH_SHORT).show();
return true;
case R.id.menuitem_share:
Toast.makeText(appContext, "share", Toast.LENGTH_SHORT).show();
return true;
case R.id.menuitem_feedback:
Toast.makeText(appContext, "feedback", Toast.LENGTH_SHORT).show();
return true;
case R.id.menuitem_about:
Toast.makeText(appContext, "about", Toast.LENGTH_SHORT).show();
return true;
case R.id.menuitem_quit:
Toast.makeText(appContext, "quit", Toast.LENGTH_SHORT).show();
return true;
}
return false;
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("tab", getActionBar().getSelectedNavigationIndex());
}
public void setText(String st) {
TextView text = (TextView)findViewById(R.id.textViewGold);
text.setText(st);
}
private class DownloadXMLFile extends AsyncTask<URL, Integer, String> {
@Override
protected String doInBackground(URL... args) {
Document doc = null;
String ret = "";
StringBuilder buffer = new StringBuilder();
try {
URL url = args[0];
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//and connect!
urlConnection.connect();
// get input stream
InputStream inputStream = urlConnection.getInputStream();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
doc = builder.parse(inputStream);
Element element = doc.getDocumentElement();
ret = element.getNodeName();
NodeList list = element.getElementsByTagName("Exrate");
String code = "";
String buy = "";
String sell = "";
String transfer = "";
for (int i=0; i < list.getLength(); i++) {
Node node = (Node)list.item(i);
NamedNodeMap map = node.getAttributes();
code = map.getNamedItem("CurrencyCode").getNodeValue();
buy = map.getNamedItem("Buy").getNodeValue();
sell = map.getNamedItem("Sell").getNodeValue();
transfer = map.getNamedItem("Transfer").getNodeValue();
buffer.append(code)
.append(System.getProperty ("line.separator"))
.append("Buy: ")
.append(buy)
.append(System.getProperty ("line.separator"))
.append("Sell: ")
.append(sell)
.append(System.getProperty ("line.separator"))
.append("Transfer: ")
.append(transfer)
.append(System.getProperty ("line.separator"));
}
ret = buffer.toString();
} catch (Exception e) {
System.out.println(">>>> EXCEPTION: " + e.getMessage());
}
return ret;
}
protected void onProgressUpdate(Integer... progress) {
}
protected void onPostExecute(String result) {
Log.i("test", result);
// after getting exchange successfully, set text into text view in first tab
setText(result);
}
}
}
class MyTabListener<T extends Fragment> implements TabListener {
private Fragment mFragment;
private final Activity mActivity;
private final String mTag;
private final Class<T> mClass;
/** * Constructor used each time a new tab is created. * * @param activity * The host Activity, used to instantiate the fragment * @param tag * The identifier tag for the fragment * @param clz * The fragment's Class, used to instantiate the fragment */
public MyTabListener(Activity activity, String tag, Class<T> clz) {
mActivity = activity;
mTag = tag;
mClass = clz;
}
/* The following are each of the ActionBar.TabListener callbacks */
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// Check if the fragment is already initialized
if (mFragment == null) {
// If not, instantiate and add it to the activity
mFragment = Fragment.instantiate(mActivity, mClass.getName());
ft.add(android.R.id.content, mFragment, mTag);
} else {
// If it exists, simply attach it in order to show it
// ft.setCustomAnimations(android.R.animator.fade_in, R.animator.animationtest);
ft.attach(mFragment);
}
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
if (mFragment != null) {
// ft.setCustomAnimations(android.R.animator.fade_in, R.animator.test);
ft.detach(mFragment);
}
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
public Fragment getFragment() {
return mFragment;
}
}
从网络获取的数据将显示在 init 的第一个选项卡上。但是当我转到第二个选项卡然后再次切换到第一个选项卡时，数据文本将不再存在。那么我们如何在第一个选项卡中保持数据文本的一致性？请帮忙