我只想使用以下代码在特定选项卡中显示 optionsMenu。
public class MainActivity extends FragmentActivity implements ActionBar.TabListener {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide fragments for each of the
* three primary sections of the app. We use a {@link android.support.v4.app.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}.
*/
AppSectionsPagerAdapter mAppSectionsPagerAdapter;
/**
* The {@link ViewPager} that will display the three primary sections of the app, one at a
* time.
*/
ViewPager mViewPager;
private int currentPage = 0;
public void onCreate(Bundle savedInstanceState) {
// this.requestWindowFeature(Window.FEATURE_NO_TITLE);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create the adapter that will return a fragment for each of the three primary sections
// of the app.
mAppSectionsPagerAdapter = new AppSectionsPagerAdapter(getSupportFragmentManager());
// Set up the action bar.
final ActionBar actionBar = getActionBar();
// Specify that the Home/Up button should not be enabled, since there is no hierarchical
// parent.
actionBar.setHomeButtonEnabled(false);
actionBar.setDisplayShowHomeEnabled(false);
actionBar.setDisplayUseLogoEnabled(false);
actionBar.setDisplayShowTitleEnabled(false);
closeOptionsMenu();
// Specify that we will be displaying tabs in the action bar.
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Set up the ViewPager, attaching the adapter and setting up a listener for when the
// user swipes between sections.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mAppSectionsPagerAdapter);
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
// When swiping between different app sections, select the corresponding tab.
// We can also use ActionBar.Tab#select() to do this if we have a reference to the
// Tab.
actionBar.setSelectedNavigationItem(position);
currentPage = position;
if (position == 2) {
openOptionsMenu();
}
else
closeOptionsMenu();
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mAppSectionsPagerAdapter.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
// listener for when this tab is selected.
actionBar.addTab(
actionBar.newTab()
.setText(mAppSectionsPagerAdapter.getPageTitle(i))
.setTabListener(this));
}
}
@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
@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 onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
@Override
public boolean onCreateOptionsMenu(Menu menu) { //this method is used for adding menu items to the Activity
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to one of the primary
* sections of the app.
*/
public static class AppSectionsPagerAdapter extends FragmentPagerAdapter {
public AppSectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int i) {
switch (i) {
default:
// The other sections of the app are dummy placeholders.
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, i + 1);
fragment.setArguments(args);
return fragment;
}
}
@Override
public int getCount() {
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
return "Section " + (position + 1);
}
}
/**
* A fragment that launches other parts of the demo application.
*/
public static class LaunchpadSectionFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_section_launchpad, container, false);
// Demonstration of a collection-browsing activity.
rootView.findViewById(R.id.demo_collection_button)
.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(getActivity(), CollectionDemoActivity.class);
startActivity(intent);
}
});
// Demonstration of navigating to external activities.
rootView.findViewById(R.id.demo_external_activity)
.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// Create an intent that asks the user to pick a photo, but using
// FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET, ensures that relaunching
// the application from the device home screen does not return
// to the external activity.
Intent externalActivityIntent = new Intent(Intent.ACTION_PICK);
externalActivityIntent.setType("image/*");
externalActivityIntent.addFlags(
Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
startActivity(externalActivityIntent);
}
});
return rootView;
}
}
/**
* A dummy fragment representing a section of the app, but that simply displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
public static final String ARG_SECTION_NUMBER = "section_number";
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_section_dummy, container, false);
Bundle args = getArguments();
((TextView) rootView.findViewById(android.R.id.text1)).setText(
getString(R.string.dummy_section_text, args.getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
}
但它不起作用。无论激活哪个片段，optionsMenu 仍然存在。（代码中的 currentPage 总是在切换选项卡时改变。）
