我正在尝试从活动中启动片段，但每次启动应用程序时，片段都会启动两次。这只发生在我在平板电脑设备上运行应用程序时。 有谁知道这个问题是什么，我该如何解决呢？
这是我的代码：
public class TestSearch extends FragmentActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
// private ActionBarDrawerToggle mDrawerToggle;
private ArrayList<Device> devices;
private ArrayList<Recepie> recepies, mainRecepies;
private ArrayList<Recepie> searchResult;
private LinearLayout sideWrapper;
private EditText src;
ArrayList<Categories> cats;
boolean isTablet = false;
@SuppressWarnings("unchecked")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test_search);
Log.v("--", "started");
if (Constants.isTablet(this)) {
isTablet = true;
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
} else {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}
devices = new ArrayList<Device>();
recepies = new ArrayList<Recepie>();
mainRecepies = new ArrayList<Recepie>();
devices = (ArrayList<Device>) getIntent().getSerializableExtra(
Constants.DEVICES_EXTRA);
recepies = getIntent().getParcelableArrayListExtra("all");
mainRecepies = getIntent().getParcelableArrayListExtra(
Constants.MAINRECEPIES);
// mTitle = mDrawerTitle = getTitle();
cats = new ArrayList<Categories>();
cats = (ArrayList<Categories>) getIntent().getSerializableExtra("cats");
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
sideWrapper = (LinearLayout) findViewById(R.id.listwraper);
// set a custom shadow that overlays the main content when the drawer
// opens
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow,
GravityCompat.START);
// set up the drawer's list view with items and click listener
// View header = getLayoutInflater().inflate(R.layout.search_item,
// null);
src = (EditText) findViewById(R.id.search_est);
src.setOnKeyListener(new OnKeyListener() {
public boolean onKey(View v, int keyCode, KeyEvent event) {
// If the event is a key-down event on the "enter" button
if ((event.getAction() == KeyEvent.ACTION_DOWN)
&& (keyCode == KeyEvent.KEYCODE_ENTER)) {
Log.v("--", "Start search");
if (src.getText().length() > 0) {
searchResult = new ArrayList<Recepie>();
final ProgressDialog progress = ProgressDialog.show(
TestSearch.this,
getString(R.string.please_wait),
getString(R.string.getting_search_results),
true);
new AsyncTask<Void, Void, Void>() {
protected void onPreExecute() {
InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(
src.getWindowToken(), 0);
};
@Override
protected Void doInBackground(Void... params) {
searchResult = getSearchResults(src.getText()
.toString());
return null;
}
protected void onPostExecute(Void result) {
// set screen to search fragment
Fragment fragment = new SideSearchFragment();
Bundle args = new Bundle();
args.putString("cat-title", src.getText()
.toString());
args.putSerializable("cats", cats);
args.putBoolean(Constants.SEARCH, true);
args.putParcelableArrayList(
Constants.SEARCH_RESULTS, searchResult);
fragment.setArguments(args);
progress.dismiss();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.add(R.id.content_frame, fragment)
.addToBackStack("search_results")
.commit();
// setTitle(mPlanetTitles[position]);
mDrawerLayout.closeDrawer(sideWrapper);
// clear search text and hide keyboard
src.setText("");
};
}.execute();
}
return true;
}
return false;
}
});
// mDrawerList.addHeaderView(header);
SideAdapter adapter = new SideAdapter(this, cats);
mDrawerList.setAdapter(adapter);
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
initActionBar();
// enable ActionBar app icon to behave as action to toggle nav drawer
getActionBar().setDisplayHomeAsUpEnabled(false);
getActionBar().setHomeButtonEnabled(true);
if (savedInstanceState == null) {
showMainFragment();
}
}
/* The click listner for ListView in the navigation drawer */
private class DrawerItemClickListener implements
ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
selectItem(position);
}
}
private void showFavoritesFragment() {
Fragment fragment = new FavoritesFragment();
Bundle args = new Bundle();
args.putSerializable("all", recepies);
args.putBoolean("search", true);
args.putSerializable("cats", cats);
fragment.setArguments(args);
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().add(R.id.content_frame, fragment)
.addToBackStack("favorites").commit();
}
private void showMainFragment() {
Fragment fragment = new MainFragment();
Bundle args = new Bundle();
Log.v("--", "START MAIN FRAGMENT !!");
args.putParcelableArrayList("all", recepies);
args.putSerializable("cats", cats);
args.putParcelableArrayList(Constants.MAINRECEPIES, mainRecepies);
args.putBoolean("search", true);
fragment.setArguments(args);
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, fragment)
.commit();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
if (mDrawerLayout.isDrawerOpen(sideWrapper))
mDrawerLayout.closeDrawer(sideWrapper);
else
mDrawerLayout.openDrawer(sideWrapper);
return true;
case R.id.main_action_fav:
showFavoritesFragment();
return true;
case R.id.main_action_choose_cats:
Intent intent = new Intent(this, CircleListActivity.class);
intent.putExtra(Constants.DEVICES_EXTRA, devices);
intent.putExtra("cats", cats);
startActivity(intent);
// finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
private void initActionBar() {
getActionBar().setBackgroundDrawable(
new ColorDrawable(Color.parseColor("#e91a34")));
getActionBar().setCustomView(R.layout.actionbar_custom_view_home);
// actionBar.setcu
getActionBar().setDisplayShowTitleEnabled(false);
getActionBar().setDisplayShowCustomEnabled(true);
getActionBar().setDisplayUseLogoEnabled(false);
getActionBar().setDisplayShowHomeEnabled(true);
getActionBar().setHomeButtonEnabled(false);
getActionBar().setIcon(R.drawable.menu);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return true;
}
private void selectItem(int position) {
// update the main content by replacing fragments
Fragment fragment = new SearchFragment();
Bundle args = new Bundle();
args.putString("cat-title", cats.get(position).getTitle());
args.putInt(Constants.CATEGORY_ID, cats.get(position).getId());
args.putSerializable("cats", cats);
fragment.setArguments(args);
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().add(R.id.content_frame, fragment)
.addToBackStack(null).commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
// setTitle(mPlanetTitles[position]);
mDrawerLayout.closeDrawer(sideWrapper);
}
@Override
public void setTitle(CharSequence title) {
// mTitle = title;
// getActionBar().setTitle(mTitle);
}
/**
* When using the ActionBarDrawerToggle, you must call it during
* onPostCreate() and onConfigurationChanged()...
*/
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
// mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
// mDrawerToggle.onConfigurationChanged(newConfig);
}
// This function gets the search results
public ArrayList<Recepie> getSearchResults(String keyword) {
ArrayList<Recepie> resultRecepie = new ArrayList<Recepie>();
JSONParser jParser = new JSONParser();
// get JSON data from URL
JSONObject jObj = jParser
.getJSONObjectFromUrl("http://oursson-recipes.outsourcingfarm.com/index.php/jsoner/getRecipe?query="
+ keyword);
try {
JSONArray withTechnics = jObj.getJSONArray("with_technics");
JSONArray withoutTechnics = jObj.getJSONArray("without_technics");
for (int i = 0; i < withTechnics.length(); i++) {
JSONObject with = withTechnics.getJSONObject(i);
boolean bool_tehcnics = true;
if (with.getInt("with_technics") == 1)
bool_tehcnics = false;
boolean my_devices = false;
if (with.getInt("mydevices") == 1)
my_devices = true;
JSONArray devices = with.getJSONArray("devices");
ArrayList<Integer> devicesIDs = new ArrayList<Integer>();
for (int k = 0; k < devices.length(); k++) {
devicesIDs.add(Integer.valueOf(devices.getString(k)));
}
resultRecepie.add(new Recepie(bool_tehcnics, my_devices, with
.getInt("id"), with.getInt("persons"), with
.getString("title"),
with.getString("preparation_time"), with
.getString("image_1"), devicesIDs));
}
for (int i = 0; i < withoutTechnics.length(); i++) {
JSONObject with = withoutTechnics.getJSONObject(i);
boolean bool_tehcnics = false;
if (with.getInt("with_technics") == 1)
bool_tehcnics = true;
boolean my_devices = false;
if (with.getInt("mydevices") == 1)
my_devices = true;
JSONArray devices = with.getJSONArray("devices");
ArrayList<Integer> devicesIDs = new ArrayList<Integer>();
for (int k = 0; k < devices.length(); k++) {
devicesIDs.add(Integer.valueOf(devices.getString(k)));
}
resultRecepie.add(new Recepie(bool_tehcnics, my_devices, with
.getInt("id"), with.getInt("persons"), with
.getString("title"),
with.getString("preparation_time"), with
.getString("image_1"), devicesIDs));
}
} catch (JSONException e) {
e.printStackTrace();
}
return resultRecepie;
}
}
我猜测onCreate()被调用两次，函数showMainFragment();被调用两次。
答案 0 :(得分：0)
当您启动Activity时，您正在致电：
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
调用此方法时，如果应用启动时平板电脑处于纵向模式，则可能会重新启动Activity。这在documentation中说明。
重新启动Activity后，再次调用onCreate，再次创建Fragment。
侧面说明：强制您的应用进入特定方向并不是一种好习惯。