项目列表布局显示在 Android Studio 中，但不显示在模拟器中
Item List Layout showing up in Android Studio, but not in Emulator
我正在开发一个 Android 应用程序，其中包含一个包含列表视图的 Recyclerview。问题是，Listview 项目出现在 Android Studio 中，XML 中没有错误，但 Listview 项目仍然没有出现在模拟器或真实设备上。我检查了布局中的各种问题——大小、宽度、布局约束——但我找不到任何问题。由于我被困在这里，我将非常感谢社区的任何帮助或提示，在此先感谢。
Activity:
package com.example.xxx;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.drawable.GradientDrawable;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.PopupMenu;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import okhttp3.Credentials;
import static com.example.xxx.SimpleItemRecyclerViewAdapter.TAGG;
import static com.example.xxx.SimpleItemRecyclerViewAdapter.palNo;
/**
* An activity representing a single Main detail screen. This
* activity is only used on narrow width devices. On tablet-size devices,
* item details are presented side-by-side with a list of items
* in a {@link MainListActivity}.
*/
public final class ProductDetailActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener,
PopupMenu.OnMenuItemClickListener {
public Context context;
private RecyclerView recyclerView;
private StockBookingsRecyclerviewAdapter recyclerviewAdapter;
private RecyclerTouchListener touchListener;
public static final String TAG = "Barcode ist:" ;
public String bookingType = null;
public String itemNo = null;
public String ean = null;
public String quantity = null;
public String packageCode = null;
public String target = null;
public String source = null;
public Date date;
public String scannedCode = null;
public static final String Profile_Prefs = "Pro_File";
public static SharedPreferences profile;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_product_detail);
TextView titleBooking = findViewById(R.id.title_booking);
TextView typeBooking = findViewById(R.id.type_booking);
TextView nameBooking = findViewById(R.id.name_booking);
TextView dateBooking = findViewById(R.id.date_booking);
Toolbar toolbar = findViewById(R.id.toolbar);
LinearLayout linearLayout = findViewById(R.id.rowFGP);
String selectedItem =null;
// Create an ArrayAdapter using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.mockdata, android.R.layout.simple_spinner_item);
// Specify the layout to use when the list of choices appears
String basic = Credentials.basic("xxx", "xxx");
// Apply the adapter to the spinner
recyclerView = findViewById(R.id.recyclerview2);
recyclerviewAdapter = new StockBookingsRecyclerviewAdapter(this);
Intent newIntent = getIntent();
String receivedPalNo = newIntent.getStringExtra("palNo");
String receivedNo = newIntent.getStringExtra("no");
String receivedType = newIntent.getStringExtra("type");
String receivedRack = newIntent.getStringExtra("rack");
String receivedCountItems = newIntent.getStringExtra("count_items");
RestClient.getStockBookings(getApplicationContext(),recyclerviewAdapter,basic);
Log.d(TAGG,"Intent 1" + receivedPalNo);
Log.d(TAGG, "Intent 2" + receivedNo);
Log.d(TAGG, "Intent 3" + receivedType);
Log.d(TAGG,"Intent 4" + receivedRack);
Log.d(TAGG, "Intent 5" + receivedCountItems);
//use a GradientDrawable with only one color set, to make it a solid color
GradientDrawable border = new GradientDrawable();
border.setColor(0x00000000); //white background
border.setStroke(1, 0xFF000000); //black border with full opacity
final ArrayList<StockBookings> stockBookingList = new ArrayList<>();
recyclerviewAdapter. setBookingList((ArrayList<StockBookings>) stockBookingList);
recyclerView.setAdapter(recyclerviewAdapter);
touchListener = new RecyclerTouchListener(this,recyclerView);
StockBookingsRecyclerviewAdapter finalRecyclerviewAdapter = recyclerviewAdapter;
touchListener
.setClickable(new RecyclerTouchListener.OnRowClickListener() {
@Override
public void onRowClicked(int position) {
}
@Override
public void onIndependentViewClicked(int independentViewID, int position) {
}
})
.setSwipeOptionViews(R.id.delete_task)
.setSwipeable(R.id.rowFGP, R.id.rowBGP, new RecyclerTouchListener.OnSwipeOptionsClickListener() {
@Override
public void onSwipeOptionClicked(int viewID, int position) {
stockBookingList.remove(position);
finalRecyclerviewAdapter.setStockBookingList(stockBookingList);
}
});
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onBackPressed() {
Intent setIntent = new Intent(getApplicationContext(),MainListActivity.class);
startActivity(setIntent);
}
public boolean onMenuItemClick(MenuItem item) {
Toast.makeText(this, "Selected Item: " +item.getTitle(), Toast.LENGTH_SHORT).show();
switch (item.getItemId()) {
case R.id.search_item:
// do your code
return true;
case R.id.upload_item:
// do your code
return true;
case R.id.copy_item:
// do your code
return true;
/* case R.id.print_item:
// do your code
return true;*/
case R.id.share_item:
// do your code
return true;
/*case R.id.bookmark_item:
// do your code
return true;*/
default:
return false;
}
}
public void onItemSelected(AdapterView<?> parent, View view,
int pos, long id) {
// An item was selected. You can retrieve the selected item using
// parent.getItemAtPosition(pos)
}
public void onNothingSelected(AdapterView<?> parent) {
// Another interface callback
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
navigateUpTo(new Intent(this, MainListActivity.class));
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onResume() {
super.onResume();
recyclerView.addOnItemTouchListener(touchListener);
}
@Override
public void onPointerCaptureChanged(boolean hasCapture) {
}
}
Activity XML:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="match_parent">
<LinearLayout
android:id="@+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="@dimen/_80sdp"
android:layout_marginBottom="12dp"
android:layout_weight="0.15"
android:background="@drawable/border_set"
android:orientation="horizontal"
app:layout_constraintBottom_toTopOf="@id/recyclerview2">
<LinearLayout
android:id="@+id/linearLayout2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="20dp"
android:text="@string/product_bookings"
android:textColor="@color/black"
android:textSize="@dimen/_20sdp"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="@+id/txt1"
app:layout_constraintEnd_toEndOf="@id/txt1" />
<TextView
android:id="@+id/txt2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="10dp"
android:text="@string/nicht_uebertragen"
android:textColor="@color/black"
android:textSize="@dimen/_10sdp"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="@+id/txt1"
app:layout_constraintEnd_toEndOf="@id/txt1" />
</LinearLayout>
</LinearLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerview2"
android:layout_width="match_parent"
android:layout_height="@dimen/_280sdp"
android:layout_weight="0.7"
tools:itemCount="7"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_constraintTop_toBottomOf="@+id/linearLayout"
tools:listitem="@layout/product_item" />
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="@dimen/_110sdp"
android:layout_weight="0.15"
android:gravity="bottom"
android:padding="5dp"
app:layout_constraintTop_toBottomOf="@id/recyclerview2"
tools:layout_editor_absoluteX="0dp">
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/floating_action_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|right"
android:layout_margin="16dp"
android:layout_marginStart="5dp"
android:layout_marginTop="5dp"
android:contentDescription="@string/fab_content_desc"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/ic_add_circle_outline" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
产品项目XML
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="wrap_content"
android:background="@drawable/background_border"
android:orientation="vertical">
<LinearLayout
android:id="@+id/rowBGP"
android:background="@color/colorPrimaryDark"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:layout_alignParentRight="true"
android:gravity="right"
android:orientation="horizontal">
<RelativeLayout
android:id="@+id/delete_task"
android:layout_width="50dp"
android:layout_height="match_parent"
android:clickable="true"
android:focusable="true"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:gravity="center"
android:orientation="vertical">
<TextView
android:id="@+id/img_delete"
android:layout_width="50dp"
android:layout_marginTop="@dimen/_1sdp"
android:layout_height="59dp"
android:background="@color/light_red"
android:text="@string/edit_article"
android:textSize="12dp"
android:textStyle="bold|italic"
app:tint="@android:color/white" />
</LinearLayout>
</RelativeLayout>
</LinearLayout>
<LinearLayout
android:id="@+id/rowFGP"
android:layout_width="match_parent"
android:layout_height="60dp"
android:background="@android:color/white"
android:clickable="true"
android:elevation="4dp"
android:focusable="true"
android:orientation="horizontal"
android:layout_margin="1dp"
android:visibility="visible">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:foreground="?attr/selectableItemBackground">
<TextView
android:id="@+id/title_booking"
style="@style/TextAppearance.AppCompat.Medium"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="@dimen/_2sdp"
android:layout_marginBottom="32dp"
android:lines="1"
android:text="@string/product_bookings"
android:textFontWeight="900"
android:textSize="@dimen/_15sdp"
android:textStyle="bold|italic"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.888" />
<TextView
android:id="@+id/type_booking"
android:text="@string/booking_type"
style="@style/TextAppearance.AppCompat.Headline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:textSize="@dimen/_10sdp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.265"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.615" />
<TextView
android:id="@+id/name_booking"
android:text="@string/name_booking"
style="@style/TextAppearance.AppCompat.Headline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="24dp"
android:textSize="@dimen/_15sdp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.265"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.615" />
<TextView
android:id="@+id/date_booking"
android:text="@string/date_booking"
style="@style/TextAppearance.AppCompat.Medium"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:layout_marginEnd="8dp"
android:lines="1"
android:textFontWeight="900"
android:textSize="@dimen/_15sdp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.888"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
</RelativeLayout>
设置适配器时，stockBookingList为空。
这意味着当 RecyclerView 决定呈现列表中的项目时，它发现 itemCount 为 0。
这会指示 RecylcerView 不呈现列表中的任何内容，因为它不会调用 onCreateViewHolder 或 onBindViewHolder – 这两种方法负责扩充列表项和设置必要的数据。
如果您有静态项目列表，则需要将它们提供给适配器。
如果列表来自您的 RestClient，您需要在收到来自 API 的数据时更新适配器。
我正在开发一个 Android 应用程序，其中包含一个包含列表视图的 Recyclerview。问题是，Listview 项目出现在 Android Studio 中，XML 中没有错误，但 Listview 项目仍然没有出现在模拟器或真实设备上。我检查了布局中的各种问题——大小、宽度、布局约束——但我找不到任何问题。由于我被困在这里，我将非常感谢社区的任何帮助或提示，在此先感谢。
Activity:
package com.example.xxx;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.drawable.GradientDrawable;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.PopupMenu;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import okhttp3.Credentials;
import static com.example.xxx.SimpleItemRecyclerViewAdapter.TAGG;
import static com.example.xxx.SimpleItemRecyclerViewAdapter.palNo;
/**
* An activity representing a single Main detail screen. This
* activity is only used on narrow width devices. On tablet-size devices,
* item details are presented side-by-side with a list of items
* in a {@link MainListActivity}.
*/
public final class ProductDetailActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener,
PopupMenu.OnMenuItemClickListener {
public Context context;
private RecyclerView recyclerView;
private StockBookingsRecyclerviewAdapter recyclerviewAdapter;
private RecyclerTouchListener touchListener;
public static final String TAG = "Barcode ist:" ;
public String bookingType = null;
public String itemNo = null;
public String ean = null;
public String quantity = null;
public String packageCode = null;
public String target = null;
public String source = null;
public Date date;
public String scannedCode = null;
public static final String Profile_Prefs = "Pro_File";
public static SharedPreferences profile;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_product_detail);
TextView titleBooking = findViewById(R.id.title_booking);
TextView typeBooking = findViewById(R.id.type_booking);
TextView nameBooking = findViewById(R.id.name_booking);
TextView dateBooking = findViewById(R.id.date_booking);
Toolbar toolbar = findViewById(R.id.toolbar);
LinearLayout linearLayout = findViewById(R.id.rowFGP);
String selectedItem =null;
// Create an ArrayAdapter using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.mockdata, android.R.layout.simple_spinner_item);
// Specify the layout to use when the list of choices appears
String basic = Credentials.basic("xxx", "xxx");
// Apply the adapter to the spinner
recyclerView = findViewById(R.id.recyclerview2);
recyclerviewAdapter = new StockBookingsRecyclerviewAdapter(this);
Intent newIntent = getIntent();
String receivedPalNo = newIntent.getStringExtra("palNo");
String receivedNo = newIntent.getStringExtra("no");
String receivedType = newIntent.getStringExtra("type");
String receivedRack = newIntent.getStringExtra("rack");
String receivedCountItems = newIntent.getStringExtra("count_items");
RestClient.getStockBookings(getApplicationContext(),recyclerviewAdapter,basic);
Log.d(TAGG,"Intent 1" + receivedPalNo);
Log.d(TAGG, "Intent 2" + receivedNo);
Log.d(TAGG, "Intent 3" + receivedType);
Log.d(TAGG,"Intent 4" + receivedRack);
Log.d(TAGG, "Intent 5" + receivedCountItems);
//use a GradientDrawable with only one color set, to make it a solid color
GradientDrawable border = new GradientDrawable();
border.setColor(0x00000000); //white background
border.setStroke(1, 0xFF000000); //black border with full opacity
final ArrayList<StockBookings> stockBookingList = new ArrayList<>();
recyclerviewAdapter. setBookingList((ArrayList<StockBookings>) stockBookingList);
recyclerView.setAdapter(recyclerviewAdapter);
touchListener = new RecyclerTouchListener(this,recyclerView);
StockBookingsRecyclerviewAdapter finalRecyclerviewAdapter = recyclerviewAdapter;
touchListener
.setClickable(new RecyclerTouchListener.OnRowClickListener() {
@Override
public void onRowClicked(int position) {
}
@Override
public void onIndependentViewClicked(int independentViewID, int position) {
}
})
.setSwipeOptionViews(R.id.delete_task)
.setSwipeable(R.id.rowFGP, R.id.rowBGP, new RecyclerTouchListener.OnSwipeOptionsClickListener() {
@Override
public void onSwipeOptionClicked(int viewID, int position) {
stockBookingList.remove(position);
finalRecyclerviewAdapter.setStockBookingList(stockBookingList);
}
});
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onBackPressed() {
Intent setIntent = new Intent(getApplicationContext(),MainListActivity.class);
startActivity(setIntent);
}
public boolean onMenuItemClick(MenuItem item) {
Toast.makeText(this, "Selected Item: " +item.getTitle(), Toast.LENGTH_SHORT).show();
switch (item.getItemId()) {
case R.id.search_item:
// do your code
return true;
case R.id.upload_item:
// do your code
return true;
case R.id.copy_item:
// do your code
return true;
/* case R.id.print_item:
// do your code
return true;*/
case R.id.share_item:
// do your code
return true;
/*case R.id.bookmark_item:
// do your code
return true;*/
default:
return false;
}
}
public void onItemSelected(AdapterView<?> parent, View view,
int pos, long id) {
// An item was selected. You can retrieve the selected item using
// parent.getItemAtPosition(pos)
}
public void onNothingSelected(AdapterView<?> parent) {
// Another interface callback
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
navigateUpTo(new Intent(this, MainListActivity.class));
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onResume() {
super.onResume();
recyclerView.addOnItemTouchListener(touchListener);
}
@Override
public void onPointerCaptureChanged(boolean hasCapture) {
}
}
Activity XML:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="match_parent">
<LinearLayout
android:id="@+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="@dimen/_80sdp"
android:layout_marginBottom="12dp"
android:layout_weight="0.15"
android:background="@drawable/border_set"
android:orientation="horizontal"
app:layout_constraintBottom_toTopOf="@id/recyclerview2">
<LinearLayout
android:id="@+id/linearLayout2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="20dp"
android:text="@string/product_bookings"
android:textColor="@color/black"
android:textSize="@dimen/_20sdp"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="@+id/txt1"
app:layout_constraintEnd_toEndOf="@id/txt1" />
<TextView
android:id="@+id/txt2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="10dp"
android:text="@string/nicht_uebertragen"
android:textColor="@color/black"
android:textSize="@dimen/_10sdp"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="@+id/txt1"
app:layout_constraintEnd_toEndOf="@id/txt1" />
</LinearLayout>
</LinearLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerview2"
android:layout_width="match_parent"
android:layout_height="@dimen/_280sdp"
android:layout_weight="0.7"
tools:itemCount="7"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_constraintTop_toBottomOf="@+id/linearLayout"
tools:listitem="@layout/product_item" />
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="@dimen/_110sdp"
android:layout_weight="0.15"
android:gravity="bottom"
android:padding="5dp"
app:layout_constraintTop_toBottomOf="@id/recyclerview2"
tools:layout_editor_absoluteX="0dp">
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/floating_action_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|right"
android:layout_margin="16dp"
android:layout_marginStart="5dp"
android:layout_marginTop="5dp"
android:contentDescription="@string/fab_content_desc"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/ic_add_circle_outline" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
产品项目XML
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="wrap_content"
android:background="@drawable/background_border"
android:orientation="vertical">
<LinearLayout
android:id="@+id/rowBGP"
android:background="@color/colorPrimaryDark"
android:layout_width="wrap_content"
android:layout_height="60dp"
android:layout_alignParentRight="true"
android:gravity="right"
android:orientation="horizontal">
<RelativeLayout
android:id="@+id/delete_task"
android:layout_width="50dp"
android:layout_height="match_parent"
android:clickable="true"
android:focusable="true"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:gravity="center"
android:orientation="vertical">
<TextView
android:id="@+id/img_delete"
android:layout_width="50dp"
android:layout_marginTop="@dimen/_1sdp"
android:layout_height="59dp"
android:background="@color/light_red"
android:text="@string/edit_article"
android:textSize="12dp"
android:textStyle="bold|italic"
app:tint="@android:color/white" />
</LinearLayout>
</RelativeLayout>
</LinearLayout>
<LinearLayout
android:id="@+id/rowFGP"
android:layout_width="match_parent"
android:layout_height="60dp"
android:background="@android:color/white"
android:clickable="true"
android:elevation="4dp"
android:focusable="true"
android:orientation="horizontal"
android:layout_margin="1dp"
android:visibility="visible">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:foreground="?attr/selectableItemBackground">
<TextView
android:id="@+id/title_booking"
style="@style/TextAppearance.AppCompat.Medium"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="@dimen/_2sdp"
android:layout_marginBottom="32dp"
android:lines="1"
android:text="@string/product_bookings"
android:textFontWeight="900"
android:textSize="@dimen/_15sdp"
android:textStyle="bold|italic"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.888" />
<TextView
android:id="@+id/type_booking"
android:text="@string/booking_type"
style="@style/TextAppearance.AppCompat.Headline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:textSize="@dimen/_10sdp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.265"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.615" />
<TextView
android:id="@+id/name_booking"
android:text="@string/name_booking"
style="@style/TextAppearance.AppCompat.Headline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="24dp"
android:textSize="@dimen/_15sdp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.265"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.615" />
<TextView
android:id="@+id/date_booking"
android:text="@string/date_booking"
style="@style/TextAppearance.AppCompat.Medium"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:layout_marginEnd="8dp"
android:lines="1"
android:textFontWeight="900"
android:textSize="@dimen/_15sdp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.888"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
</RelativeLayout>
设置适配器时，stockBookingList为空。
这意味着当 RecyclerView 决定呈现列表中的项目时，它发现 itemCount 为 0。
这会指示 RecylcerView 不呈现列表中的任何内容，因为它不会调用 onCreateViewHolder 或 onBindViewHolder – 这两种方法负责扩充列表项和设置必要的数据。
如果您有静态项目列表，则需要将它们提供给适配器。
如果列表来自您的 RestClient，您需要在收到来自 API 的数据时更新适配器。