卡片视图不可见
Card view is not visible
我正在尝试添加带有回收站视图的卡片视图。但它没有显示任何内容，只是一个空白视图。
我在这里看到了这方面的问题，它有为回收站视图和卡片视图添加依赖项的答案。这存在于我的 gradle 中。另一种是像这样使用 getItemCount：
@Override
public int getItemCount() {
return mImage.length;
}
这也是我认为是对的我用过list.size();
我不明白发生了什么。我想从数据库中检索数据，可能是出错了。有谁能帮忙吗
TableListAdapter
public class TableListAdapter extends RecyclerView.Adapter<TableListAdapter.TableViewHolder> {
TimeTableHelper db;
private List<TimeTable> List;
public TableListAdapter(List<TimeTable> List) {
this.List = List;
}
@Override
public int getItemCount() {
return List.size();
}
@Override
public void onBindViewHolder(TableViewHolder contactViewHolder, int i) {
TimeTable table = db.getTables(i);
TimeTable ci = List.get(i);
contactViewHolder.tableTitle.setText(table.getTitle());
}
@Override
public TableViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View itemView = LayoutInflater.
from(viewGroup.getContext()).
inflate(R.layout.table_card, viewGroup, false);
return new TableViewHolder(itemView);
}
public static class TableViewHolder extends RecyclerView.ViewHolder {
protected TextView tableTitle;
protected CardView cv;
protected Switch aSwitch;
public TableViewHolder(View v) {
super(v);
tableTitle = (TextView) v.findViewById(R.id.tableTitle);
cv = (CardView) v.findViewById(R.id.card_view);
aSwitch = (Switch) v.findViewById(R.id.switch2);
}
}
}
时间表列表Activity
public class TimeTableList extends AppCompatActivity {
private RecyclerView recyclerView;
public ArrayList<TimeTable> items;
public TableListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_time_table_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Time Table");
toolbar.setTitleTextColor(Color.parseColor("#FFFFFF"));
toolbar.setNavigationIcon(R.drawable.ic_arrow_back_white_24dp);
setSupportActionBar(toolbar);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
recyclerView = (RecyclerView)findViewById(R.id.RecyclerView);
LinearLayoutManager llm = new LinearLayoutManager(this);
items=new ArrayList<>();
recyclerView.setLayoutManager(llm);
recyclerView.setHasFixedSize(true);
initRecyclerAdapter();
ImageButton fab = (ImageButton) findViewById(R.id.imgbtn_fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),NewTimeTable.class);
startActivity(i);
}
});
}
private void initRecyclerAdapter() {
adapter = new TableListAdapter(items);
recyclerView.setAdapter(adapter);
}
}
列表xml布局：
<?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="match_parent" android:fitsSystemWindows="true"
tools:context="com.example.siddhi.timetablelayout.activities.TimeTableList">
<android.support.design.widget.AppBarLayout android:layout_height="wrap_content"
android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay"
android:id="@+id/view5">
<android.support.v7.widget.Toolbar android:id="@+id/toolbar"
android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay"
app:titleTextAppearance="@style/Toolbar.TitleText"/>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:layout_height="match_parent"
android:layout_width="match_parent"
android:id="@+id/RecyclerView"
android:background="@android:color/white"
android:layout_below="@+id/view5" />
<LinearLayout
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_gravity="bottom|end">
<include layout="@layout/myfab"/>
</LinearLayout>
</RelativeLayout>
table_card xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="1"
android:orientation="vertical"
android:measureWithLargestChild="false">
<!-- A CardView that contains a TextView -->
<android.support.v7.widget.CardView
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="@+id/card_view"
android:layout_width="match_parent"
android:layout_height="60dp"
card_view:cardCornerRadius="4dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="10dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_marginLeft="20dp"
android:textAppearance="@android:style/TextAppearance.Medium"
android:id="@+id/tableTitle" />
<Switch
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/switch2"
android:layout_centerVertical="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_marginRight="20dp" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
Gradle:
apply plugin: 'com.android.application'
android {
compileSdkVersion 23
buildToolsVersion '23.0.1'
defaultConfig {
applicationId "com.example.siddhi.timetablelayout"
minSdkVersion 16
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
compile 'com.android.support:design:23.1.1'
compile 'com.android.support:appcompat-v7:23.1.1'
compile 'com.android.support:cardview-v7:23.1.1'
compile 'com.android.support:recyclerview-v7:23.1.1'
compile 'com.google.android.gms:play-services:8.3.0'
compile 'com.google.android.gms:play-services-wearable:8.3.0'
compile 'com.google.android.gms:play-services-maps:7.5.0'
compile 'com.google.android.support:wearable:1.3.0'
}
TimeTableHelper:
public class TimeTableHelper extends SQLiteOpenHelper{
private static final String TABLE_TIME_TABLE = "timetables";
private static final String KEY_TABLE_TITLE = "tabletitle";
private static final String KEY_STATUS = "status";
private static final String KEY_TABLE_ID = "tableid";
private static final String KEY_TABLE_COLOR = "tablecolor";
public TimeTableHelper(Context context) {
super(context, Constants.DATABASE_NAME, null, Constants.DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_TIME_TABLE);
// createTable(db);
// onCreate(db);
}
public void addTimeTable(TimeTable table) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_TABLE_TITLE, table.getTitle());
values.put(KEY_STATUS, table.getStatus());
values.put(KEY_TABLE_COLOR, table.getTableColor());
db.insert(TABLE_TIME_TABLE, null, values);
db.close();
}
public TimeTable getTables(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_TIME_TABLE, new String[] { KEY_TABLE_ID,
KEY_TABLE_TITLE, KEY_TABLE_COLOR ,KEY_STATUS}, KEY_TABLE_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
cursor.moveToFirst();
TimeTable table = new TimeTable(Integer.parseInt(cursor.getString(0)),
cursor.getString(1), Integer.parseInt(cursor.getString(2)),Integer.parseInt(cursor.getString(3)));
return table;
}
public List<TimeTable> getAllTables() {
List<TimeTable> conList = new ArrayList<TimeTable>();
String selectQuery = "SELECT * FROM " + TABLE_TIME_TABLE;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
TimeTable table = new TimeTable();
table.setId(Integer.parseInt(cursor.getString(0)));
table.setTitle(cursor.getString(1));
table.setStatus(cursor.getInt(2));
table.setTableColor(Integer.parseInt(cursor.getString(3)));
conList.add(table);
} while (cursor.moveToNext());
}
return conList;
}
}
创建 table:
String CREATE_TIME_TABLE = "CREATE TABLE " + TABLE_TIME_TABLE + "("
+ KEY_TABLE_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ KEY_TABLE_TITLE + " TEXT,"
+ KEY_STATUS + " TEXT,"
+ KEY_TABLE_COLOR + " TEXT" + ")";
db.execSQL(CREATE_TIME_TABLE);
谢谢..
据我所知，您将一个空列表传递到 TimeTableList (activity) 中的 TableListAdapter。
由于在创建适配器期间列表大小为 0，因此不会为 RecyclerView 创建任何 cardView。
在创建 TableListAdapter
的实例 之前，您应该 在列表中添加一些数据点
或
在 TableListAdapter 中有一个 public void updateRecyclerAdapter(List itemList)，您可以调用 post 创建适配器的实例。
该方法可能类似于下面的代码
public void updateAdapaterList(List<TimeTable> newTimeTableList) {
//Replace the current list with new list
this.List = newTimeTableList;
//notify the adapter that the data set has changed
notifyDataSetChanged();
}
还有
确保重写 RecyclerAdapter 中的 getItemCount() 方法，如下所示。
@Override
public int getItemCount() {
return List.size();
}
此外，我强烈建议在编码时使用适当的 camelCasing。 :)
从您的代码中我可以看出您忘记将数据点添加到 items 变量
只需将您的 activity 代码更改为此，我所做的更改是添加了@VaibhavSinghal 提供的功能来更新您的回收器视图适配器，然后通过传递您从 TimeTableHelper.getAllTables()
public class TimeTableList extends AppCompatActivity {
private RecyclerView recyclerView;
public ArrayList<TimeTable> items;
public TableListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_time_table_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Time Table");
toolbar.setTitleTextColor(Color.parseColor("#FFFFFF"));
toolbar.setNavigationIcon(R.drawable.ic_arrow_back_white_24dp);
setSupportActionBar(toolbar);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
recyclerView = (RecyclerView)findViewById(R.id.RecyclerView);
LinearLayoutManager llm = new LinearLayoutManager(this);
items=new ArrayList<>();
recyclerView.setLayoutManager(llm);
recyclerView.setHasFixedSize(true);
initRecyclerAdapter();
// Get reference to your time tableHelper
TimeTableHelper timeTableHelper = new TimeTableHelper(this);
// Update your adapter with elements returned by getAllTables() function
updateAdapterList(timeTableHelper.getAllTables());
ImageButton fab = (ImageButton) findViewById(R.id.imgbtn_fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),NewTimeTable.class);
startActivity(i);
}
});
}
private void initRecyclerAdapter() {
adapter = new TableListAdapter(items);
recyclerView.setAdapter(adapter);
}
public void updateAdapaterList(List<TimeTable> newTimeTableList) {
//Replace the current list with new list
this.List = newTimeTableList;
//notify the adapter that the data set has changed
notifyDataSetChanged();
}
}
正如我在您的代码中看到的那样，您没有在列表中添加内容，这就是它显示空白的原因，因为当时列表大小为 ZERO。
您只需初始化您的列表并设置适配器。在初始化适配器之前在您的列表中添加一些数据。
Your code
recyclerView = (RecyclerView)findViewById(R.id.RecyclerView);
LinearLayoutManager llm = new LinearLayoutManager(this);
items=new ArrayList<>(); // **Add data to list after initialization**
recyclerView.setLayoutManager(llm);
recyclerView.setHasFixedSize(true);
initRecyclerAdapter();
ImageButton fab = (ImageButton) findViewById(R.id.imgbtn_fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),NewTimeTable.class);
startActivity(i);
}
});
我正在尝试添加带有回收站视图的卡片视图。但它没有显示任何内容，只是一个空白视图。
我在这里看到了这方面的问题，它有为回收站视图和卡片视图添加依赖项的答案。这存在于我的 gradle 中。另一种是像这样使用 getItemCount：
@Override
public int getItemCount() {
return mImage.length;
}
这也是我认为是对的我用过list.size(); 我不明白发生了什么。我想从数据库中检索数据，可能是出错了。有谁能帮忙吗
TableListAdapter
public class TableListAdapter extends RecyclerView.Adapter<TableListAdapter.TableViewHolder> {
TimeTableHelper db;
private List<TimeTable> List;
public TableListAdapter(List<TimeTable> List) {
this.List = List;
}
@Override
public int getItemCount() {
return List.size();
}
@Override
public void onBindViewHolder(TableViewHolder contactViewHolder, int i) {
TimeTable table = db.getTables(i);
TimeTable ci = List.get(i);
contactViewHolder.tableTitle.setText(table.getTitle());
}
@Override
public TableViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View itemView = LayoutInflater.
from(viewGroup.getContext()).
inflate(R.layout.table_card, viewGroup, false);
return new TableViewHolder(itemView);
}
public static class TableViewHolder extends RecyclerView.ViewHolder {
protected TextView tableTitle;
protected CardView cv;
protected Switch aSwitch;
public TableViewHolder(View v) {
super(v);
tableTitle = (TextView) v.findViewById(R.id.tableTitle);
cv = (CardView) v.findViewById(R.id.card_view);
aSwitch = (Switch) v.findViewById(R.id.switch2);
}
}
}
时间表列表Activity
public class TimeTableList extends AppCompatActivity {
private RecyclerView recyclerView;
public ArrayList<TimeTable> items;
public TableListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_time_table_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Time Table");
toolbar.setTitleTextColor(Color.parseColor("#FFFFFF"));
toolbar.setNavigationIcon(R.drawable.ic_arrow_back_white_24dp);
setSupportActionBar(toolbar);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
recyclerView = (RecyclerView)findViewById(R.id.RecyclerView);
LinearLayoutManager llm = new LinearLayoutManager(this);
items=new ArrayList<>();
recyclerView.setLayoutManager(llm);
recyclerView.setHasFixedSize(true);
initRecyclerAdapter();
ImageButton fab = (ImageButton) findViewById(R.id.imgbtn_fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),NewTimeTable.class);
startActivity(i);
}
});
}
private void initRecyclerAdapter() {
adapter = new TableListAdapter(items);
recyclerView.setAdapter(adapter);
}
}
列表xml布局：
<?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="match_parent" android:fitsSystemWindows="true"
tools:context="com.example.siddhi.timetablelayout.activities.TimeTableList">
<android.support.design.widget.AppBarLayout android:layout_height="wrap_content"
android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay"
android:id="@+id/view5">
<android.support.v7.widget.Toolbar android:id="@+id/toolbar"
android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay"
app:titleTextAppearance="@style/Toolbar.TitleText"/>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:layout_height="match_parent"
android:layout_width="match_parent"
android:id="@+id/RecyclerView"
android:background="@android:color/white"
android:layout_below="@+id/view5" />
<LinearLayout
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_gravity="bottom|end">
<include layout="@layout/myfab"/>
</LinearLayout>
</RelativeLayout>
table_card xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="1"
android:orientation="vertical"
android:measureWithLargestChild="false">
<!-- A CardView that contains a TextView -->
<android.support.v7.widget.CardView
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="@+id/card_view"
android:layout_width="match_parent"
android:layout_height="60dp"
card_view:cardCornerRadius="4dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="10dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_marginLeft="20dp"
android:textAppearance="@android:style/TextAppearance.Medium"
android:id="@+id/tableTitle" />
<Switch
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/switch2"
android:layout_centerVertical="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_marginRight="20dp" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
Gradle:
apply plugin: 'com.android.application'
android {
compileSdkVersion 23
buildToolsVersion '23.0.1'
defaultConfig {
applicationId "com.example.siddhi.timetablelayout"
minSdkVersion 16
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
compile 'com.android.support:design:23.1.1'
compile 'com.android.support:appcompat-v7:23.1.1'
compile 'com.android.support:cardview-v7:23.1.1'
compile 'com.android.support:recyclerview-v7:23.1.1'
compile 'com.google.android.gms:play-services:8.3.0'
compile 'com.google.android.gms:play-services-wearable:8.3.0'
compile 'com.google.android.gms:play-services-maps:7.5.0'
compile 'com.google.android.support:wearable:1.3.0'
}
TimeTableHelper:
public class TimeTableHelper extends SQLiteOpenHelper{
private static final String TABLE_TIME_TABLE = "timetables";
private static final String KEY_TABLE_TITLE = "tabletitle";
private static final String KEY_STATUS = "status";
private static final String KEY_TABLE_ID = "tableid";
private static final String KEY_TABLE_COLOR = "tablecolor";
public TimeTableHelper(Context context) {
super(context, Constants.DATABASE_NAME, null, Constants.DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_TIME_TABLE);
// createTable(db);
// onCreate(db);
}
public void addTimeTable(TimeTable table) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_TABLE_TITLE, table.getTitle());
values.put(KEY_STATUS, table.getStatus());
values.put(KEY_TABLE_COLOR, table.getTableColor());
db.insert(TABLE_TIME_TABLE, null, values);
db.close();
}
public TimeTable getTables(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_TIME_TABLE, new String[] { KEY_TABLE_ID,
KEY_TABLE_TITLE, KEY_TABLE_COLOR ,KEY_STATUS}, KEY_TABLE_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
cursor.moveToFirst();
TimeTable table = new TimeTable(Integer.parseInt(cursor.getString(0)),
cursor.getString(1), Integer.parseInt(cursor.getString(2)),Integer.parseInt(cursor.getString(3)));
return table;
}
public List<TimeTable> getAllTables() {
List<TimeTable> conList = new ArrayList<TimeTable>();
String selectQuery = "SELECT * FROM " + TABLE_TIME_TABLE;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
TimeTable table = new TimeTable();
table.setId(Integer.parseInt(cursor.getString(0)));
table.setTitle(cursor.getString(1));
table.setStatus(cursor.getInt(2));
table.setTableColor(Integer.parseInt(cursor.getString(3)));
conList.add(table);
} while (cursor.moveToNext());
}
return conList;
}
}
创建 table:
String CREATE_TIME_TABLE = "CREATE TABLE " + TABLE_TIME_TABLE + "("
+ KEY_TABLE_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ KEY_TABLE_TITLE + " TEXT,"
+ KEY_STATUS + " TEXT,"
+ KEY_TABLE_COLOR + " TEXT" + ")";
db.execSQL(CREATE_TIME_TABLE);
谢谢..
据我所知，您将一个空列表传递到 TimeTableList (activity) 中的 TableListAdapter。
由于在创建适配器期间列表大小为 0，因此不会为 RecyclerView 创建任何 cardView。
在创建 TableListAdapter
或
在 TableListAdapter 中有一个 public void updateRecyclerAdapter(List itemList)，您可以调用 post 创建适配器的实例。
该方法可能类似于下面的代码
public void updateAdapaterList(List<TimeTable> newTimeTableList) {
//Replace the current list with new list
this.List = newTimeTableList;
//notify the adapter that the data set has changed
notifyDataSetChanged();
}
还有
确保重写 RecyclerAdapter 中的 getItemCount() 方法，如下所示。
@Override
public int getItemCount() {
return List.size();
}
此外，我强烈建议在编码时使用适当的 camelCasing。 :)
从您的代码中我可以看出您忘记将数据点添加到 items 变量
只需将您的 activity 代码更改为此，我所做的更改是添加了@VaibhavSinghal 提供的功能来更新您的回收器视图适配器，然后通过传递您从 TimeTableHelper.getAllTables()
public class TimeTableList extends AppCompatActivity {
private RecyclerView recyclerView;
public ArrayList<TimeTable> items;
public TableListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_time_table_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Time Table");
toolbar.setTitleTextColor(Color.parseColor("#FFFFFF"));
toolbar.setNavigationIcon(R.drawable.ic_arrow_back_white_24dp);
setSupportActionBar(toolbar);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
recyclerView = (RecyclerView)findViewById(R.id.RecyclerView);
LinearLayoutManager llm = new LinearLayoutManager(this);
items=new ArrayList<>();
recyclerView.setLayoutManager(llm);
recyclerView.setHasFixedSize(true);
initRecyclerAdapter();
// Get reference to your time tableHelper
TimeTableHelper timeTableHelper = new TimeTableHelper(this);
// Update your adapter with elements returned by getAllTables() function
updateAdapterList(timeTableHelper.getAllTables());
ImageButton fab = (ImageButton) findViewById(R.id.imgbtn_fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),NewTimeTable.class);
startActivity(i);
}
});
}
private void initRecyclerAdapter() {
adapter = new TableListAdapter(items);
recyclerView.setAdapter(adapter);
}
public void updateAdapaterList(List<TimeTable> newTimeTableList) {
//Replace the current list with new list
this.List = newTimeTableList;
//notify the adapter that the data set has changed
notifyDataSetChanged();
}
}
正如我在您的代码中看到的那样，您没有在列表中添加内容，这就是它显示空白的原因，因为当时列表大小为 ZERO。
您只需初始化您的列表并设置适配器。在初始化适配器之前在您的列表中添加一些数据。
Your code
recyclerView = (RecyclerView)findViewById(R.id.RecyclerView);
LinearLayoutManager llm = new LinearLayoutManager(this);
items=new ArrayList<>(); // **Add data to list after initialization**
recyclerView.setLayoutManager(llm);
recyclerView.setHasFixedSize(true);
initRecyclerAdapter();
ImageButton fab = (ImageButton) findViewById(R.id.imgbtn_fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),NewTimeTable.class);
startActivity(i);
}
});