在Android中如果我从活动A中启动新的活动B，Android将自动保存活动A的所有状态。因此，当我在活动B中单击设备上的后退按钮时，A将恢复到我拥有的状态开始活动B（例如：Spinners，ListView和Toggle Buttons都在以前的位置）。
但是，当我单击操作栏中的后退按钮时，活动A开始时没有存储状态。 有没有办法让这个后退按钮类似于设备的背面，或者我必须使用SharedPreferences并自己存储每件事情？
（我的应用程序为api 8及以上版本）
在我的应用程序中的一个片段中，我有一个ListView，它是从下一页返回时需要处于相同状态的片段之一。我在下面添加了代码。 如果需要任何其他部分，请告诉我，我将添加代码。
主要活动代码： 私人ProgressDialog进展;
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a {@link FragmentPagerAdapter}
* derivative, which will keep every loaded fragment in memory. If this
* becomes too memory intensive, it may be best to switch to a
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle(Farsi.Convert(getString(R.string.app_name_farsi)));
setContentView(R.layout.activity_main);
final ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Create the adapter that will return a fragment for each of the three primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
// When swiping between different sections, select the corresponding tab. We can also use ActionBar.Tab#select() to do this if we have a reference to the Tab.
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
// Create a tab with text corresponding to the page title defined by the adapter. Also specify this Activity object, which implements the TabListener interface, as the callback (listener) for when this tab is selected.
actionBar.addTab(actionBar.newTab().setText(mSectionsPagerAdapter.getPageTitle(i)).setTabListener(this));
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will automatically handle clicks on the Home/Up button, so long as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
Intent intent=new Intent(MainActivity.this, AboutActivity.class);
startActivity(intent);
}
return super.onOptionsItemSelected(item);
}
@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
// When the given tab is selected, switch to the corresponding page in the ViewPager.
mViewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
以下是我的List Fragment的代码：
public class SearchResultListFragment extends Fragment{
Pagination pagination;
boolean loadingMore = false;
ListView list;
TextView text1;
TextView text2;
TextView text3;
TextView text4;
TextView text5;
Button Btngetdata;
private static String url = "https://www.....com/api/property/search";
private static int currentFirstVisibleItem;
public SearchResultArrayListAdaptor adapter ;
LinearLayout linlaHeaderProgress;
JSONArray jsonArray = null;
JSONParse fetchclass = null;
public SearchResultListFragment() {
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
linlaHeaderProgress = (LinearLayout) getActivity().findViewById(R.id.linlaHeaderProgress);
ArrayAdapter<PropertyObject> aa =(ArrayAdapter<PropertyObject>) list.getAdapter();
if (aa!= null){
aa.clear();
aa.notifyDataSetChanged();
}
list.setOnItemClickListener((OnItemClickListener) getActivity());
adapter = new SearchResultArrayListAdaptor(getActivity(), R.layout.list_view_items, new ArrayList<PropertyObject>());
list.setAdapter(adapter);
pagination = new Pagination(0,15);
fetchclass = new JSONParse(getActivity());
fetchclass.execute(url);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_search_result_list, container, false);
list=(ListView)rootView.findViewById(R.id.listViewSearchResult);
list.setOnScrollListener(
new OnScrollListener(){
private int currentVisibleItemCount;
private int currentTotalItemCount;
private int currentScrollState;
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
this.currentScrollState = scrollState;
this.isScrollCompleted();
}
private void isScrollCompleted() {
if (currentFirstVisibleItem + currentVisibleItemCount >= currentTotalItemCount) {
if (this.currentVisibleItemCount > 0 && this.currentScrollState == SCROLL_STATE_IDLE) {
if(fetchclass!=null) {
pagination = new Pagination(this.currentTotalItemCount,15);
if(!(fetchclass.getStatus()== AsyncTask.Status.RUNNING)) {
fetchclass= new JSONParse(getActivity());
fetchclass.execute(url);
}
}
else {
fetchclass = new JSONParse(getActivity());
fetchclass.execute(url);
}
}
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
currentFirstVisibleItem = firstVisibleItem;
this.currentVisibleItemCount = visibleItemCount;
this.currentTotalItemCount = totalItemCount;
}
});
return rootView;
}
//*********************************** inner class
public class JSONParse extends AsyncTask<String, String, JSONObject> {
Context mContext;
int checkBoxRooms;
public JSONParse(Context context){
mContext = context;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
linlaHeaderProgress.setVisibility(View.VISIBLE);
}
@Override
protected JSONObject doInBackground(String... args) {
JSONObject json = null;
PropertyFilter searchFilter = SearchFilterManager.initializePropertyFilter(new PropertyFilter(), getArguments());
getActivity().setProgressBarIndeterminateVisibility(true);
JSONParserForSearch jParser = new JSONParserForSearch();
json = jParser.getJSONFromUrl(url, searchFilter, pagination);
return json;
}
@Override
protected void onPostExecute(JSONObject json) {
// SHOW THE SPINNER WHILE LOADING FEEDS
getActivity().setProgressBarIndeterminateVisibility(false);
PropertyObject propertyObject;
try {
jsonArray = json.getJSONArray("PropertyListings");
if (jsonArray == null || jsonArray.length()<1){
// list.setEmptyView(getActivity().findViewById(R.id.txtNoResult));
}
else {
for(int i = 0; i < jsonArray.length(); i++){
JSONObject c = jsonArray.getJSONObject(i);
propertyObject = new Gson().fromJson(c.toString(), new PropertyObject().getClass());
adapter.add(propertyObject);
adapter.notifyDataSetChanged();
}
}
// CHANGE THE LOADINGMORE STATUS TO PERMIT FETCHING MORE DATA
loadingMore = false;
// HIDE THE SPINNER AFTER LOADING FEEDS
linlaHeaderProgress.setVisibility(View.GONE);
}
catch (JSONException e) {
e.printStackTrace();
}
catch (Exception e) {
e.printStackTrace();
}
}
}
}
我的布局XML：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
<ListView
android:id="@+id/listViewSearchResult"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_weight="2"
>
</ListView>
<LinearLayout
android:id="@+id/linlaHeaderProgress"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="vertical"
android:visibility="gone"
>
我的适配器是ArrayAdapter。 我也实现了isEmpty和getCount。
我的列表活动：
public class SearchResultListActivity extends ActionBarActivity implements OnItemClickListener{
static PropertyObject selectedPropertyObject;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = getIntent();
Bundle bundle=new Bundle();
bundle.putInt("intentionOfOwner", intent.getIntExtra("intentionOfOwner",0));
SearchResultListFragment fragobj=new SearchResultListFragment();
fragobj.setArguments(bundle);
///back button
setContentView(R.layout.activity_search_result_list);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction().add(R.id.container, fragobj).commit();
}
}
@Override
public void onItemClick(AdapterView<?> arg0, View textView, int rowNumber, long arg3) {
Intent intent = new Intent(this, PropertyDetailActivity.class);
PropertyObject po = (PropertyObject) arg0.getAdapter().getItem((int)arg3);
intent.putExtra("listingID",po.getID());
startActivity(intent);
}
编辑： 行。我将API级别从8更改为11。 我还添加了getActionBar（）。setDisplayHomeAsUpEnabled（true）;到onCreate（）的活动。 并更改onOptionsItemSelected如下。
public boolean onOptionsItemSelected（MenuItem item）{
switch (item.getItemId()) {
case R.id.action_settings:
Intent intent=new Intent(PropertyDetailActivity.this, AboutActivity.class);
startActivity(intent);
return true;
case R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
case R.id.up:
NavUtils.navigateUpFromSameTask(this);
return true;
case R.id.homeAsUp:
NavUtils.navigateUpFromSameTask(this);
return true;
default:
break;
}
return super.onOptionsItemSelected(item);
但是当我单击操作栏中的后退按钮时，没有一个开关案例有机会运行！