java - 可见性设置为 GONE 时如何删除空白空间
问题描述
我已将可见性设置RecyclerView为消失。我怎样才能删除它占用的空白空间？
我试着把layout_heightas wrap_content，但它仍然没有显示任何东西。
回收商视图：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycleView"
android:layout_gravity="top"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteX="1dp"
tools:layout_editor_absoluteY="1dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
卡片视图：
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="250dp"
android:layout_marginLeft="10dp"
android:layout_marginTop="10dp"
android:layout_marginRight="10dp"
android:id="@+id/cardView"
android:backgroundTint="#5A10E7"
android:elevation="90dp"
android:orientation="vertical"
android:textColor="#FFFFFF"
app:cardCornerRadius="25dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.282">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/Requestfulfilled"
android:layout_width="139dp"
android:layout_height="41dp"
android:layout_weight="1"
android:backgroundTint="#4CAF50"
android:clickable="true"
android:defaultFocusHighlightEnabled="true"
android:hint="Request Fullfilled"
android:text="Fulfilled"
android:textColor="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/DeleteRequest"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="@+id/RlocationView"
app:layout_constraintTop_toBottomOf="@+id/RlocationView" />
<Button
android:id="@+id/DeleteRequest"
android:layout_width="139dp"
android:layout_height="41dp"
android:backgroundTint="#F44336"
android:clickable="true"
android:defaultFocusHighlightEnabled="true"
android:hint="Delete"
android:text="Delete"
android:textColor="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="@+id/RlocationView"
app:layout_constraintHorizontal_bias="0.894"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.904" />
<TextView
android:id="@+id/RemailView"
android:layout_width="340dp"
android:layout_height="35dp"
android:allowUndo="true"
android:focusable="auto"
android:focusableInTouchMode="true"
android:text="Email"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="18sp"
app:layout_constraintBottom_toTopOf="@+id/RdateView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/RbloodView"
android:layout_width="116dp"
android:layout_height="35dp"
android:allowUndo="true"
android:focusable="auto"
android:focusableInTouchMode="true"
android:text="Blood Group"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="18sp"
app:layout_constraintBottom_toTopOf="@+id/RlocationView"
app:layout_constraintEnd_toStartOf="@+id/RdateView"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/RemailView" />
<TextView
android:id="@+id/RdateView"
android:layout_width="164dp"
android:layout_height="42dp"
android:allowUndo="true"
android:focusable="auto"
android:focusableInTouchMode="true"
android:text="Date of Requirement"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="18sp"
app:layout_constraintBottom_toTopOf="@+id/RlocationView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="@+id/RbloodView"
app:layout_constraintTop_toBottomOf="@+id/RemailView" />
<TextView
android:id="@+id/RlocationView"
android:layout_width="340dp"
android:layout_height="35dp"
android:allowUndo="true"
android:focusable="auto"
android:focusableInTouchMode="true"
android:text="Location"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="18sp"
app:layout_constraintBottom_toTopOf="@+id/Requestfulfilled"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/RdateView" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
将卡片可见性设置为 GONE 的代码：
public class yourRequestActivity extends AppCompatActivity {
private RecyclerView cardView;
private DatabaseReference dbRefForReq, dbRefForResp;
private FirebaseAuth mAuth;
private String AuthUserEmail, UserID;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.request_response_view);
mAuth = FirebaseAuth.getInstance();
AuthUserEmail = mAuth.getCurrentUser().getEmail();
UserID = mAuth.getCurrentUser().getUid();
dbRefForResp = FirebaseDatabase.getInstance().getReference().child("Responses").child(String.valueOf(UserID));
dbRefForReq = FirebaseDatabase.getInstance().getReference().child("Blood Requests");
dbRefForReq.keepSynced(true);
cardView = (RecyclerView) findViewById(R.id.recycleView);
cardView.setHasFixedSize(true);
cardView.setLayoutManager(new LinearLayoutManager(this));
}
@Override
protected void onStart() {
super.onStart();
FirebaseRecyclerOptions<getDbContents> options =
new FirebaseRecyclerOptions.Builder<getDbContents>()
.setQuery(dbRefForReq, getDbContents.class)
.build();
FirebaseRecyclerAdapter<getDbContents, contentHolder> adapter = new FirebaseRecyclerAdapter<getDbContents, contentHolder>(options) {
@Override
protected void onBindViewHolder(@NonNull final contentHolder holder, final int position, @NonNull final getDbContents model) {
final int finalPosition = position + 1;
if (model.getUser().equals(AuthUserEmail)) {
dbRefForReq.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
DataSnapshot checkFulfillment = dataSnapshot.child(String.valueOf(("Request " + finalPosition))).child("Fulfillment");
if (checkFulfillment.exists()) {
if (checkFulfillment.child("Fulfilled").getValue().equals("yes")) {
/*------------- Set current user card as visible -----------------*/
holder.frameView.setVisibility(View.VISIBLE);
holder.fulfilled.setVisibility(View.GONE);
holder.requestFulfilled.setVisibility(View.VISIBLE);
holder.userEmail.setText(AuthUserEmail);
holder.bloodGroup.setText(model.getBloodGroup());
holder.dateOfRequirement.setText(model.getDate());
holder.Location.setText(model.getLocation());
////////////////////////////////////////////////////////////////////
}
} else {
holder.frameView.setVisibility(View.VISIBLE);
holder.fulfilled.setVisibility(View.VISIBLE);
holder.requestFulfilled.setVisibility(View.GONE);
/*------------- Set current user card as visible -----------------*/
holder.userEmail.setText(AuthUserEmail);
holder.bloodGroup.setText(model.getBloodGroup());
holder.dateOfRequirement.setText(model.getDate());
holder.Location.setText(model.getLocation());
////////////////////////////////////////////////////////////////////
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
} else if (model.getUser().equals(null)) {
holder.userEmail.setText("You have not posted any request");
} else {
holder.frameView.setVisibility(View.GONE);
}
/* Fulfilled and Delete button Functionality */
holder.fulfilled.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Map<String, Object> response = new HashMap<>();
response.put("Fulfilled", "yes");
/*-----------------Remove Responses------------------*/
dbRefForResp.removeValue();
///////////////////////////////////////////////////////
/*-----------------Update and insert child with fulfilled status as yes------------------*/
dbRefForReq.child(String.valueOf(("Request " + finalPosition))).child("Fulfillment").setValue(response).addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void aVoid) {
Toast.makeText(yourRequestActivity.this, "Request fulfillment status posted", Toast.LENGTH_SHORT).show();
}
});
////////////////////////////////////////////////////////////////////
holder.fulfilled.setVisibility(View.GONE);
holder.requestFulfilled.setVisibility(View.VISIBLE);
}
});
}
@NonNull
@Override
public contentHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.your_request_card, viewGroup, false);
contentHolder contentViewHolder = new contentHolder(view);
return contentViewHolder;
}
};
cardView.setAdapter(adapter);
adapter.startListening();
}
public class contentHolder extends RecyclerView.ViewHolder {
TextView userEmail, bloodGroup, dateOfRequirement, Location, requestFulfilled;
Button fulfilled;
FrameLayout frameView;
public contentHolder(@NonNull View itemView) {
super(itemView);
userEmail = itemView.findViewById(R.id.RemailView);
bloodGroup = itemView.findViewById(R.id.RbloodView);
dateOfRequirement = itemView.findViewById(R.id.RdateView);
Location = itemView.findViewById(R.id.RlocationView);
requestFulfilled = (TextView) itemView.findViewById(R.id.fulfilledTextMessage);
frameView = (FrameLayout) itemView.findViewById(R.id.cardFrame);
fulfilled = (Button) itemView.findViewById(R.id.Requestfulfilled);
}
}
}
我想删除可见性设置为 GONE 时出现的空白，如下面的快照所示。
解决方案
RecyclerView即使可见性设置为消失，您也会占用空间。它仍然需要空间，因为有些项目RecyclerView要显示。尽管您可以通过删除RecyclerView要显示的项目来解决此问题。如果您想再次显示它会占用大量内存，RecyclerView因为您仍然需要重新添加项目。我会推荐的是RecyclerView用一个布局来包装你，例如。LinearLayout并将该布局的可见性设置为消失。
尝试这样做：
<LinearLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!-- Place your RecyclerView here -->
<!-- change visibility of container view -->
</LinearLayout>
*编辑：你没有很好地解释它。我现在得到你想要的。您只需从RecyclerView列表中删除该项目。最好的方法是使用DiffUtil. 这是一个很棒的在线教程，展示了如何在 Java 中实现它。https://codinginflow.com/tutorials/android/room-viewmodel-livedata-recyclerview-mvvm/part-1-introduction
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