[英]Detecting up and down swipes on a Recyclerview in a fragment how can I do that?
所以我有一個加載了 Firebase Firestore 文檔的 recyclerview,我想看看它是向上還是向下滑動。 根據我要制作的方向 adapter.startListening(); 如果他向下滑動,則再次停止。 如果用戶向下滾動,我還想隱藏一個按鈕。 我只需要弄清楚我怎樣才能看到他是否這樣做?
這段代碼可以左右工作,但由於某種原因不能上下工作?
new ItemTouchHelper( new ItemTouchHelper.SimpleCallback(0,
ItemTouchHelper.UP | ItemTouchHelper.DOWN) {
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
return false;
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
if(direction == ItemTouchHelper.UP){
Toast.makeText(getActivity(), "You swiped up", Toast.LENGTH_LONG).show();
}
}
});
這里是完整的代碼,如果它出於某種原因干擾了 smth 不知道
public class HomeFragment extends Fragment {
View myFragment;
private ImageButton postButton;
CollectionReference postsRef;
FirebaseFirestore db;
private PostsAdapter adapter;
FirebaseAuth mAuth;
RecyclerView recyclerView;
public static ProfileFragment getInstance() {
return new ProfileFragment();
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
myFragment = inflater.inflate(R.layout.fragment_home, container, false);
postButton = myFragment.findViewById( R.id.postButton);
recyclerView = myFragment.findViewById(R.id.postlist);
mAuth = FirebaseAuth.getInstance();
db = FirebaseFirestore.getInstance();
postsRef = db.collection("posts");
SetupRecyclerView();
postButton.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
SendUserToPostActivity();
}
});
new ItemTouchHelper( new ItemTouchHelper.SimpleCallback(0,
ItemTouchHelper.UP | ItemTouchHelper.DOWN) {
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
return false;
}
@Override
public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
if(direction == ItemTouchHelper.UP){
Toast.makeText(getActivity(), "You swiped up", Toast.LENGTH_LONG).show();
}
}
});
adapter.setOnConfirmClickListener( new PostsAdapter.onConfirmClickListener() {
@Override
public void onConfirmClick(DocumentSnapshot documentSnapshot, int position) {
Posts post = documentSnapshot.toObject(Posts.class);
String id = documentSnapshot.getId();
if(post.getUid().equals(mAuth.getCurrentUser().getUid())){
adapter.deleteItem(position);
Toast.makeText(getActivity(), "Post deleted", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(getActivity(), "You cannot delete this", Toast.LENGTH_LONG).show();
}
}
});
return myFragment;
}
@Override
public void onStart(){
super.onStart();
adapter.startListening();
}
@Override
public void onStop() {
super.onStop();
adapter.stopListening();
}
private void SetupRecyclerView() {
Query query = postsRef.orderBy("time", Query.Direction.DESCENDING);
FirestoreRecyclerOptions<Posts> options = new FirestoreRecyclerOptions.Builder<Posts>().setQuery(query, Posts.class).build();
adapter = new PostsAdapter(options);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setAdapter(adapter);
}
private void SendUserToPostActivity() {
Intent postIntent = new Intent(getActivity(), PostActivity.class);
startActivity(postIntent);
}
}
您使用了錯誤的偵聽器。 ItemTouchHelper
適用於 recyclerview 中的單個項目,而不是整個視圖。
您正在尋找的是OnScrollListener
:
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
}
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
//This is where you can track a scroll change
}
});
onScrolled
方法中的dy
指的是滾動事件中 y position 的變化,對於dx
也是如此。
在該方法中,假設您想檢查 recyclerview 是否達到向上或向下滾動的限制,然后在該onScroll
方法(或您正在檢查的任何地方)中,您可以添加對recyclerView.canScrollVertically(int)
的調用. int
的值為 -1 表示 UP,1 表示 DOWN,0 表示 FALSE,即不能滾動。
檢查recyclerview是否到達底部:
if(!recyclerView.canScrollVertically(1)){
//The recyclerview can no longer scroll downwards, you have reached the bottom
}
編輯添加:您的itemTouchHelper
也無法正常工作,因為要在回調的第一個參數中指定垂直方向,而在第二個參數中指定水平方向。 您為第一個參數傳遞了 0,因此它認為沒有垂直方向作為選項
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