无法在 CardView 中设置 RecyclerView？
Can't set RecyclerView inside CardView?
我正在尝试将 RecyclerView 放入 CardView 并动态创建项目。
显然，在 XML 中，RecyclerView 设置在 CardView tag 内部，但正如您所看到的图片，RecyclerView 项是在 CardView 外部创建的。
（RecyclerView's items是照片中kg和set的部分。而CardView也是另一个RecyclerView的项目。）
有什么问题？
XML
<androidx.cardview.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="12dp"
android:layout_marginLeft="12dp"
android:layout_marginRight="12dp"
app:cardElevation="10dp">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:id="@+id/ll1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="@+id/workout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="8dp"
android:text="TEST"/>
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="@color/light_blue_400"/>
</LinearLayout>
<LinearLayout
android:id="@+id/ll2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintTop_toBottomOf="@+id/ll1">
<com.google.android.material.button.MaterialButton
android:id="@+id/delete"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginStart="8dp"
android:layout_marginEnd="4dp"
style="@style/RoutineButtonStyle"
android:text="DELETE"
app:icon="@drawable/ic_delete"/>
<com.google.android.material.button.MaterialButton
android:id="@+id/add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginStart="4dp"
android:layout_marginEnd="8dp"
style="@style/RoutineButtonStyle"
android:text="ADD"
app:icon="@drawable/ic_add"/>
</LinearLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/rv"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="10dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/ll2"
android:orientation="vertical"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
如果您需要任何其他代码，请告诉我。
这是您的 add/delete CardView 的 Activity:
//Item List if you want to add one or more Items
private List<MyItem> myItems = new ArrayList<>();
private Adapter smallCardAdapter;
private int size;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView recyclerView = findViewById(R.id.rv);
//Creates a new Object in the Adapter.class
smallCardAdapter = new Adapter();
recyclerView.setAdapter(smallCardAdapter);
CardView cardView = findViewById(R.id.cardView);
MaterialButton delete = findViewById(R.id.delete);
MaterialButton add = findViewById(R.id.add);
//Add onClickListener
add.setOnClickListener(v -> {
try {
size = myItems.size();
//if the value is 0, a new item is created
//if you want to delete the card after 0 than you have to change the value to 0
if(size == 0){
//Creates a new Object in the MyItem.class
myItems.add(new MyItem("Set","1kg"));
}else{
MyItem myItem = myItems.get(0);
//Replace kg with "" to make a Integer
String secondString = myItem.getSecondString().replace("kg","");
Integer value = Integer.valueOf(secondString);
value++;
myItem.setSecondString(value+"kg");
myItems.set(0,myItem);
}
updateAdapter();
}catch (Exception e){
Log.w("MainActivity","Add Button OnClickListener");
e.printStackTrace();
}
});
//Delete onClickListener
delete.setOnClickListener(v->{
try {
size = myItems.size();
//If the value is 0 then canceled to avoid errors
if(size == 0){
return;
}
MyItem myItem = myItems.get(0);
//Replace kg with "" to make a Integer
String secondString = myItem.getSecondString().replace("kg","");
Integer value = Integer.valueOf(secondString);
//if the value is one or lower
if(value <= 1){
//The card will deleted after updateAdapter();
myItems.clear();
}else{
value--;
myItem.setSecondString(value+"kg");
myItems.set(0,myItem);
}
updateAdapter();
}catch (Exception e){
Log.w("MainActivity","Delete Button OnClickListener");
e.printStackTrace();
}
});
}
private void updateAdapter(){
try {
smallCardAdapter.setItems(myItems);
}catch (Exception e){
Log.w("MainActivity","updateAdapter");
e.printStackTrace();
}
}
名为 MyItem 的自定义项：
public class MyItem {
String firstString;
String secondString;
public MyItem(String firstString,String secondString){
this.firstString = firstString;
this.secondString = secondString;
}
public String getFirstString() {
return firstString;
}
public void setFirstString(String firstString) {
this.firstString = firstString;
}
public String getSecondString() {
return secondString;
}
public void setSecondString(String secondString) {
this.secondString = secondString;
}
}
Adapter.java 创建一个 smallCard:
public class Adapter extends RecyclerView.Adapter<Adapter.SmallCardHolder> {
private List<MyItem> items = new ArrayList<>();
@NonNull
@Override
public SmallCardHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
// I created a new smallcard for the CardView
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.smallcard, parent, false);
SmallCardHolder smallCardHolder = new SmallCardHolder(itemView);
return smallCardHolder;
}
@Override
public void onBindViewHolder(@NonNull final SmallCardHolder holder, int position) {
//get the current item of the position
MyItem myItem = items.get(position);
String firstString = myItem.getFirstString();
String secondString = myItem.getSecondString();
holder.textViewSet.setText(firstString);
holder.textViewkg.setText(secondString);
}
@Override
public int getItemCount () {
return items.size();
}
public void setItems(List <MyItem> items) {
this.items = items;
notifyDataSetChanged();
}
class SmallCardHolder extends RecyclerView.ViewHolder {
//Here are the TextView's of the smallcard (smallcard.xml)
private TextView textViewSet;
private TextView textViewkg;
public SmallCardHolder(@NonNull View itemView) {
super(itemView);
textViewSet = itemView.findViewById(R.id.set);
textViewkg = itemView.findViewById(R.id.kg);
}
}
}
为 Adapter.java 创建一个名称为 smallcard.xml 的新布局：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/set"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Set"
android:layout_centerVertical="true"
android:textSize="18sp"
android:layout_marginStart="5dp"
android:textColor="?attr/colorPrimary"
android:textStyle="bold"/>
<TextView
android:id="@+id/kg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="kg"
android:layout_toRightOf="@id/set"
android:layout_marginLeft="55dp"
android:layout_centerVertical="true"
android:textColor="?attr/colorPrimary"
android:textSize="16sp"
android:layout_marginRight="10dp"
android:maxLines="1"/>
</RelativeLayout>
</RelativeLayout>
在您的 XML 中，您必须为 CardView 命名。我称之为cardView。这是代码 android:id="@+id/cardView"
结果：
您将在代码中找到更多信息作为注释。
我正在尝试将 RecyclerView 放入 CardView 并动态创建项目。
显然，在 XML 中，RecyclerView 设置在 CardView tag 内部，但正如您所看到的图片，RecyclerView 项是在 CardView 外部创建的。
（RecyclerView's items是照片中kg和set的部分。而CardView也是另一个RecyclerView的项目。）
有什么问题？
XML
<androidx.cardview.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="12dp"
android:layout_marginLeft="12dp"
android:layout_marginRight="12dp"
app:cardElevation="10dp">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:id="@+id/ll1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="@+id/workout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="8dp"
android:text="TEST"/>
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="@color/light_blue_400"/>
</LinearLayout>
<LinearLayout
android:id="@+id/ll2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintTop_toBottomOf="@+id/ll1">
<com.google.android.material.button.MaterialButton
android:id="@+id/delete"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginStart="8dp"
android:layout_marginEnd="4dp"
style="@style/RoutineButtonStyle"
android:text="DELETE"
app:icon="@drawable/ic_delete"/>
<com.google.android.material.button.MaterialButton
android:id="@+id/add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginStart="4dp"
android:layout_marginEnd="8dp"
style="@style/RoutineButtonStyle"
android:text="ADD"
app:icon="@drawable/ic_add"/>
</LinearLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/rv"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="10dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/ll2"
android:orientation="vertical"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
如果您需要任何其他代码，请告诉我。
这是您的 add/delete CardView 的 Activity:
//Item List if you want to add one or more Items
private List<MyItem> myItems = new ArrayList<>();
private Adapter smallCardAdapter;
private int size;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView recyclerView = findViewById(R.id.rv);
//Creates a new Object in the Adapter.class
smallCardAdapter = new Adapter();
recyclerView.setAdapter(smallCardAdapter);
CardView cardView = findViewById(R.id.cardView);
MaterialButton delete = findViewById(R.id.delete);
MaterialButton add = findViewById(R.id.add);
//Add onClickListener
add.setOnClickListener(v -> {
try {
size = myItems.size();
//if the value is 0, a new item is created
//if you want to delete the card after 0 than you have to change the value to 0
if(size == 0){
//Creates a new Object in the MyItem.class
myItems.add(new MyItem("Set","1kg"));
}else{
MyItem myItem = myItems.get(0);
//Replace kg with "" to make a Integer
String secondString = myItem.getSecondString().replace("kg","");
Integer value = Integer.valueOf(secondString);
value++;
myItem.setSecondString(value+"kg");
myItems.set(0,myItem);
}
updateAdapter();
}catch (Exception e){
Log.w("MainActivity","Add Button OnClickListener");
e.printStackTrace();
}
});
//Delete onClickListener
delete.setOnClickListener(v->{
try {
size = myItems.size();
//If the value is 0 then canceled to avoid errors
if(size == 0){
return;
}
MyItem myItem = myItems.get(0);
//Replace kg with "" to make a Integer
String secondString = myItem.getSecondString().replace("kg","");
Integer value = Integer.valueOf(secondString);
//if the value is one or lower
if(value <= 1){
//The card will deleted after updateAdapter();
myItems.clear();
}else{
value--;
myItem.setSecondString(value+"kg");
myItems.set(0,myItem);
}
updateAdapter();
}catch (Exception e){
Log.w("MainActivity","Delete Button OnClickListener");
e.printStackTrace();
}
});
}
private void updateAdapter(){
try {
smallCardAdapter.setItems(myItems);
}catch (Exception e){
Log.w("MainActivity","updateAdapter");
e.printStackTrace();
}
}
名为 MyItem 的自定义项：
public class MyItem {
String firstString;
String secondString;
public MyItem(String firstString,String secondString){
this.firstString = firstString;
this.secondString = secondString;
}
public String getFirstString() {
return firstString;
}
public void setFirstString(String firstString) {
this.firstString = firstString;
}
public String getSecondString() {
return secondString;
}
public void setSecondString(String secondString) {
this.secondString = secondString;
}
}
Adapter.java 创建一个 smallCard:
public class Adapter extends RecyclerView.Adapter<Adapter.SmallCardHolder> {
private List<MyItem> items = new ArrayList<>();
@NonNull
@Override
public SmallCardHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
// I created a new smallcard for the CardView
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.smallcard, parent, false);
SmallCardHolder smallCardHolder = new SmallCardHolder(itemView);
return smallCardHolder;
}
@Override
public void onBindViewHolder(@NonNull final SmallCardHolder holder, int position) {
//get the current item of the position
MyItem myItem = items.get(position);
String firstString = myItem.getFirstString();
String secondString = myItem.getSecondString();
holder.textViewSet.setText(firstString);
holder.textViewkg.setText(secondString);
}
@Override
public int getItemCount () {
return items.size();
}
public void setItems(List <MyItem> items) {
this.items = items;
notifyDataSetChanged();
}
class SmallCardHolder extends RecyclerView.ViewHolder {
//Here are the TextView's of the smallcard (smallcard.xml)
private TextView textViewSet;
private TextView textViewkg;
public SmallCardHolder(@NonNull View itemView) {
super(itemView);
textViewSet = itemView.findViewById(R.id.set);
textViewkg = itemView.findViewById(R.id.kg);
}
}
}
为 Adapter.java 创建一个名称为 smallcard.xml 的新布局：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/set"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Set"
android:layout_centerVertical="true"
android:textSize="18sp"
android:layout_marginStart="5dp"
android:textColor="?attr/colorPrimary"
android:textStyle="bold"/>
<TextView
android:id="@+id/kg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="kg"
android:layout_toRightOf="@id/set"
android:layout_marginLeft="55dp"
android:layout_centerVertical="true"
android:textColor="?attr/colorPrimary"
android:textSize="16sp"
android:layout_marginRight="10dp"
android:maxLines="1"/>
</RelativeLayout>
</RelativeLayout>
在您的 XML 中，您必须为 CardView 命名。我称之为cardView。这是代码 android:id="@+id/cardView"
结果：
您将在代码中找到更多信息作为注释。