[英]Calling a method in a fragment in a FragmentStatePagerAdapter from the activity that created it
I have an activity that has a navigation drawer and a Fragment state adapter. 我有一个具有导航抽屉和Fragment状态适配器的活动。 When ever I click something in the navigation drawer I am passing that info to the mainactivity via a interface.And then I am passing that data to the main fragment which is in Fragmentstateadapter.
每当我单击导航抽屉中的某个内容时,我都会通过界面将该信息传递给mainactivity,然后将该数据传递给Fragmentstateadapter中的主片段。 The problem is when ever the screen rotates I get a null pointer exception for the main fragment.`
问题是,每当屏幕旋转时,主片段都会出现空指针异常。
public class MainActivity extends ActionBarActivity implements RightDrawerRecyclerAdapter.Filters,
LeftDrawerFragment.MenuSection,CommonAsyncTask.ServerData {
private static final String TAG = MainActivity.class.getSimpleName();
public MainFragment mMainFragment;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewPager pager = (ViewPager) findViewById(R.id.pager);
ScreenSlidePagerAdapter pagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
pager.setAdapter(pagerAdapter);
}
@Override
public void getMenuSelection(int selection) {
Log.d(TAG,"getMenuSelection->"+selection);
mMainFragment.getMenuSelection(selection);
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
Log.d(TAG, "in screenslide");
}
@Override
public Fragment getItem(int position) {
if (position == 0) {
Log.d(TAG, "in returning MainFragment");
mMainFragment=new MainFragment();
return mMainFragment;
} else {
return new MapViewFragment();
}
}
@Override
public int getCount() {
return 2;
}
@Override
public CharSequence getPageTitle(int position) {
if (position == 0) {
return "List";
} else {
return "Map";
}
}
}}
So getMenuSelection is the method from the interface in navigation drawer. 因此,getMenuSelection是导航抽屉中界面的方法。 Then I have a method with the same name in my main fragment in MainFragment.So when ever I select something in the navigation drawer I can change contents in the main fragment but when ever I turn my screen a new instance of MainFragment is getting created and getItem(int position) is not getting trigged so my MainFragment object is null and now I cant pass data from my navigation drawer to main fragment.I tried making MainFragment object as static and that created problems in my MainFragment class.
然后我在MainFragment的主片段中有一个同名的方法,所以每当我在导航抽屉中选择某个内容时,我都可以更改主片段中的内容,但是每当我打开屏幕时,都会创建一个新的MainFragment实例并getItem(int position)没有被触发,所以我的MainFragment对象为null,现在我无法将数据从导航抽屉传递给主片段。我试图将MainFragment对象设置为静态对象,这在MainFragment类中造成了问题。
So how can I get back the same MainFragment object even when the screen is turned. 因此,即使屏幕被转动,我也如何找回相同的MainFragment对象。 Or is there any better way to pass data between navigation drawer fragment and a fragment in FragmentState adapter
还是有更好的方法在导航抽屉片段和FragmentState适配器中的片段之间传递数据
大家好,我通过接口通过onAttach将MainFragment的当前实例发送回MainActivity来解决了这个问题
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