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アクティビティ（Firebaseからのデータを取得）から別のフラグメントにデータを送信しようとしています。 Firebase上でデータを変更しても、アクティビティが作成されている間は最初の試行では変更されません。最初の試行で、メソッドのpassDataToInfoFragmentとpassDataToRanklistFragmentのフラグメントは常にNULLです。私は理由が分からないので、私は助けが必要です。私のフラグメントがインスタンス化されないのはなぜですか？フラグメントアクティビティのアクティビティ
GroupDetailFragmentCommunication：
public interface GroupDetailFragmentCommunication {
public void passDataToInfoFragment(PublicGroup group);
public void passDataToRanklistFragment(PublicGroup group);
}GroupDetailActivity：
public class GroupDetailActivity extends AppCompatActivity implements GroupDetailFragmentCommunication{
private FirebaseAuth auth;
private FirebaseDatabase database;
private DatabaseReference reference;
private GroupDetailPagerAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_group_detail);
this.initFirebase();
this.setUpToolbar();
this.setUpTabLayout();
this.getPublicGroup();
}
public void initFirebase() {
auth = FirebaseAuth.getInstance();
database = FirebaseDatabase.getInstance();
reference = database.getReference();
}
public void setUpToolbar() {
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Details");
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
public void setUpTabLayout() {
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
ArrayList<String> tabs = new ArrayList<>();
tabs.add("Info");
tabs.add("Rank");
final ViewPager viewPager = (ViewPager) findViewById(R.id.viewPager);
this.adapter = new GroupDetailPagerAdapter(getSupportFragmentManager(), tabs);
viewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(viewPager);
}
public void getPublicGroup() {
reference.child("groups").child("public").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
PublicGroup pg = snapshot.getValue(PublicGroup.class);
if (pg != null) {
pg.setKey(snapshot.getKey());
passDataToInfoFragment(pg);
passDataToRanklistFragment(pg);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
@Override
public void passDataToInfoFragment(PublicGroup group) {
InfoFragment fragment = (InfoFragment) this.adapter.getFragment(0);
if (fragment != null) {
fragment.fragmentCommunication(group);
} else {
Log.i("Bla", "Fragment 1 is not instantiated");
}
}
s
@Override
public void passDataToRanklistFragment(PublicGroup group) {
RanklistFragment fragment = (RanklistFragment) this.adapter.getFragment(1);
if (fragment != null) {
fragment.fragmentCommunication(group);
} else {
Log.i("Bla", "Fragment 2 is not instantiated");
}
}
}GroupDetailPagerAdapter：あなたのコードでチラッ後
public class GroupDetailPagerAdapter extends FragmentStatePagerAdapter {
private SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
private ArrayList<String> tabHeader;
public GroupDetailPagerAdapter(FragmentManager fm, ArrayList<String> tabHeader) {
super(fm);
this.tabHeader = tabHeader;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
Fragment infoTab = new InfoFragment();
return infoTab;
case 1:
Fragment ranklistTab = new RanklistFragment();
return ranklistTab;
default:
return null;
}
}
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment = (Fragment) super.instantiateItem(container, position);
registeredFragments.put(position, fragment);
return fragment;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
registeredFragments.remove(position);
super.destroyItem(container, position, object);
}
public Fragment getFragment(int position) {
return registeredFragments.get(position);
}
@Override
public CharSequence getPageTitle(int position) {
return tabHeader.get(position);
}
}
Thxと呼ばれるようになって、今それは動作します！ –