我在 RecyclerView 中添加数据，但数据没有立即反映出来
I am adding data in RecyclerView but data is not getting reflected instantly
我正在尝试在 Recycler View 中添加数据，但我从 Edit Text 中提取的数据并未立即插入。只有在我执行一些其他操作（如删除列表）后才会插入数据。
我在这里附上了我所有的代码。
我认为当我尝试从编辑文本添加新文本时 notifyDataSetChanged 没有被调用。
代码：
MainActivity.java
package com.example.sqlitedatabase;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
Adapter adapter;
RecyclerView recyclerView;
TextView textView;
ImageView addTodo;
ConstraintLayout constraintLayout;
ConstraintLayout editTextContainer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<ListModel> list = new ArrayList<>();
editTextContainer = findViewById(R.id.constraintParentOfAddTodo);
textView = findViewById(R.id.textView);
addTodo = findViewById(R.id.addTodo);
addData(list);
addTodo_onClickListener(list);
adapter = new Adapter(this);
recyclerView = findViewById(R.id.recyclerView);
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter.setList(list);
}
private void addTodo_onClickListener(ArrayList<ListModel> list) {
addTodo.setOnClickListener(v -> {
addTodo.setVisibility(View.GONE);
View view = getLayoutInflater().inflate(R.layout.after_add_clicked, null, false);
//Used for USERS input
EditText editText = (EditText) view.findViewById(R.id.editTextTodo);
//This ImageView is used as a button to set data in list
ImageView setTodo = (ImageView) view.findViewById(R.id.sendTodo);
Animation animAddTodo = AnimationUtils.loadAnimation(MainActivity.this, R.anim.righttoleft);
view.setAnimation(animAddTodo);
editTextContainer.addView(view);
setTodo_onClickListener(editText, setTodo, list, view);
});
}
private void setTodo_onClickListener(EditText editText, ImageView setTodo, ArrayList<ListModel> list, View view) {
setTodo.setOnClickListener(v -> {
String txt = editText.getText().toString();
addToList(list, txt);
view.setVisibility(View.GONE);
addTodo.setVisibility(View.VISIBLE);
}
);
}
//this function is Supposed to add new data to To do list
private void addToList(ArrayList<ListModel> list, String text) {
//no work is done on id
list.add(new ListModel(1, text, true));
}
//for displaying list initially
//this data gets inserted instantly
//No problem with them.
private void addData(ArrayList<ListModel> list) {
list.add(new ListModel(1, "1", false));
list.add(new ListModel(2, "2", false));
list.add(new ListModel(3, "3", false));
list.add(new ListModel(4, "4", false));
list.add(new ListModel(5, "5", false));
list.add(new ListModel(6, "6", false));
list.add(new ListModel(7, "7", false));
list.add(new ListModel(8, "8", false));
list.add(new ListModel(9, "9", false));
list.add(new ListModel(10, "10", false));
}
Adapter.java
package com.example.sqlitedatabase;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.cardview.widget.CardView;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
private final Context context;
private ArrayList<ListModel> list = new ArrayList<>();
public Adapter(Context context) {
this.context = context;
}
@NonNull
@Override
public Adapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_template, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull Adapter.ViewHolder holder, int position) {
holder.todoText.setText(list.get(position).getText());
holder.notDoneBtn.setOnClickListener(v -> {
if (list.size() != 0) {
list.remove(list.get(position));
notifyDataSetChanged();
}
}
);
}
@Override
public int getItemCount() {
return list.size();
}
public void setList(ArrayList<ListModel> list) {
this.list = list;
notifyDataSetChanged();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
private final TextView todoText;
private final ImageView doneBtn;
private final ImageView notDoneBtn;
private final RelativeLayout listBlock;
public ViewHolder(@NonNull View itemView) {
super(itemView);
listBlock=itemView.findViewById(R.id.listBlock);
todoText = itemView.findViewById(R.id.todoText);
doneBtn = itemView.findViewById(R.id.doneBtn);
notDoneBtn = itemView.findViewById(R.id.notDoneBtn);
}
}
}
activity_main.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:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:background="@color/white"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="200dp"
android:layout_height="120dp"
android:layout_marginTop="4dp"
android:fontFamily="sans-serif-condensed"
android:gravity="center"
android:text="TO-DO LIST"
android:textSize="28sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.502"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</TextView>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintLayout3"
android:layout_width="300dp"
android:layout_height="480dp"
android:layout_marginTop="12dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView"
app:layout_constraintVertical_bias="0.0">
<ScrollView
android:layout_width="300dp"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.50">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="280dp"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="12dp">
</androidx.recyclerview.widget.RecyclerView>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintParentOfAddTodo"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginBottom="2dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/constraintLayout3"
app:layout_constraintVertical_bias="0.794">
<ImageView
android:id="@+id/addTodo"
android:layout_width="44dp"
android:layout_height="44dp"
android:layout_marginVertical="0dp"
android:backgroundTint="@color/white"
android:elevation="10dp"
android:src="@drawable/add_circle_48px"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.956"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</ImageView>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
list_template.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"
android:layout_height="42dp"
android:id="@+id/listBlock"
android:layout_width="280dp"
android:layout_gravity="center_horizontal">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_gravity="center_horizontal"
android:layout_marginTop="2dp"
android:layout_marginStart="1dp"
android:elevation="200dp"
app:cardBackgroundColor="#932"
app:cardCornerRadius="5dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/todoText"
android:layout_width="190dp"
android:layout_height="40dp"
android:layout_marginStart="10dp"
android:fontFamily="monospace"
android:gravity="center_vertical"
android:maxHeight="40dp"
android:padding="5dp"
android:text="Reading books"
android:textColor="#EFEBE9"
android:textSize="14sp"
android:textStyle="bold">
</TextView>
<ImageView
android:id="@+id/notDoneBtn"
android:layout_width="32dp"
android:layout_height="32dp"
android:layout_alignBottom="@id/todoText"
android:padding="5dp"
android:layout_marginStart="5dp"
android:layout_marginTop="4dp"
android:layout_marginBottom="4dp"
android:layout_toEndOf="@+id/todoText"
android:background="#999999"
android:src="@drawable/close_20px">
</ImageView>
<ImageView
android:id="@+id/doneBtn"
android:layout_width="32dp"
android:layout_height="32dp"
android:layout_marginStart="4dp"
android:layout_marginTop="5dp"
android:layout_marginBottom="4dp"
android:layout_toEndOf="@+id/notDoneBtn"
android:background="#999999"
android:padding="5dp"
android:src="@drawable/done_20px">
</ImageView>
</RelativeLayout>
</androidx.cardview.widget.CardView>
</RelativeLayout>
after_add_clicked.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">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginBottom="2dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent">
<com.google.android.material.card.MaterialCardView
android:id="@+id/materialCardView"
android:layout_width="310dp"
android:layout_height="match_parent"
android:layout_marginStart="50dp"
android:background="#121212"
android:backgroundTint="@color/white"
app:cardCornerRadius="30dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:strokeColor="#888"
app:strokeWidth="2dp">
<EditText
android:id="@+id/editTextTodo"
android:layout_width="300dp"
android:layout_height="40dp"
android:layout_gravity="center"
android:background="@color/white"
android:fontFamily="monospace"
android:gravity="center_vertical"
android:text="What to do"
android:inputType="text"
android:textSize="20sp">
</EditText>
</com.google.android.material.card.MaterialCardView>
<ImageView
android:id="@+id/sendTodo"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_margin="4dp"
android:layout_marginStart="4dp"
android:layout_marginTop="4dp"
android:layout_marginEnd="4dp"
android:layout_marginBottom="4dp"
android:src="@drawable/ic_baseline_send_24"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.529"
app:layout_constraintStart_toEndOf="@+id/materialCardView"
app:layout_constraintTop_toTopOf="parent">
</ImageView>
<ImageView
android:id="@+id/cancel"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_margin="4dp"
android:layout_marginStart="4dp"
android:layout_marginTop="4dp"
android:layout_marginEnd="4dp"
android:layout_marginBottom="4dp"
android:src="@drawable/close_20px"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/materialCardView"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</ImageView>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
这是我的应用程序的外观。
如果您调用 addToList 来添加您的数据，所做的只是将一个新项目插入到您的 Activity 和适配器正在共享的列表中 - 适配器不知道有任何更改, 所以它不会更新显示
你应该在适配器上调用你的 setList 函数 - 用新列表替换当前列表（如果它实际上是同一个列表并不重要）然后调用 notifyDataSetChanged()显示“新”列表。
在你的适配器上有这样的功能总是更好 - 当你有新数据时，你只需将它传递给适配器，它可以在内部处理更新自身的细节。传递数据的东西不需要知道任何关于它的信息。如果你想稍后更新适配器的工作方式（比如更具体地更新某些项目，或者使用 DiffUtil），那么这仍然是一个内部细节——传递数据的东西只需要传递数据照常。
（你应该 setList 复制传入的列表，就像 list.toList() - 如果某些东西修改了原始列表，你不希望适配器的内部列表发生变化，这可能会导致错误。这里没问题，但是如果您使用 DiffUtil，例如，您的 oldList 也将是您的 newList，没有差异意味着没有更新）
我正在尝试在 Recycler View 中添加数据，但我从 Edit Text 中提取的数据并未立即插入。只有在我执行一些其他操作（如删除列表）后才会插入数据。
我在这里附上了我所有的代码。
我认为当我尝试从编辑文本添加新文本时 notifyDataSetChanged 没有被调用。
代码：
MainActivity.java
package com.example.sqlitedatabase;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
Adapter adapter;
RecyclerView recyclerView;
TextView textView;
ImageView addTodo;
ConstraintLayout constraintLayout;
ConstraintLayout editTextContainer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<ListModel> list = new ArrayList<>();
editTextContainer = findViewById(R.id.constraintParentOfAddTodo);
textView = findViewById(R.id.textView);
addTodo = findViewById(R.id.addTodo);
addData(list);
addTodo_onClickListener(list);
adapter = new Adapter(this);
recyclerView = findViewById(R.id.recyclerView);
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
adapter.setList(list);
}
private void addTodo_onClickListener(ArrayList<ListModel> list) {
addTodo.setOnClickListener(v -> {
addTodo.setVisibility(View.GONE);
View view = getLayoutInflater().inflate(R.layout.after_add_clicked, null, false);
//Used for USERS input
EditText editText = (EditText) view.findViewById(R.id.editTextTodo);
//This ImageView is used as a button to set data in list
ImageView setTodo = (ImageView) view.findViewById(R.id.sendTodo);
Animation animAddTodo = AnimationUtils.loadAnimation(MainActivity.this, R.anim.righttoleft);
view.setAnimation(animAddTodo);
editTextContainer.addView(view);
setTodo_onClickListener(editText, setTodo, list, view);
});
}
private void setTodo_onClickListener(EditText editText, ImageView setTodo, ArrayList<ListModel> list, View view) {
setTodo.setOnClickListener(v -> {
String txt = editText.getText().toString();
addToList(list, txt);
view.setVisibility(View.GONE);
addTodo.setVisibility(View.VISIBLE);
}
);
}
//this function is Supposed to add new data to To do list
private void addToList(ArrayList<ListModel> list, String text) {
//no work is done on id
list.add(new ListModel(1, text, true));
}
//for displaying list initially
//this data gets inserted instantly
//No problem with them.
private void addData(ArrayList<ListModel> list) {
list.add(new ListModel(1, "1", false));
list.add(new ListModel(2, "2", false));
list.add(new ListModel(3, "3", false));
list.add(new ListModel(4, "4", false));
list.add(new ListModel(5, "5", false));
list.add(new ListModel(6, "6", false));
list.add(new ListModel(7, "7", false));
list.add(new ListModel(8, "8", false));
list.add(new ListModel(9, "9", false));
list.add(new ListModel(10, "10", false));
}
Adapter.java
package com.example.sqlitedatabase;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.cardview.widget.CardView;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
private final Context context;
private ArrayList<ListModel> list = new ArrayList<>();
public Adapter(Context context) {
this.context = context;
}
@NonNull
@Override
public Adapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_template, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull Adapter.ViewHolder holder, int position) {
holder.todoText.setText(list.get(position).getText());
holder.notDoneBtn.setOnClickListener(v -> {
if (list.size() != 0) {
list.remove(list.get(position));
notifyDataSetChanged();
}
}
);
}
@Override
public int getItemCount() {
return list.size();
}
public void setList(ArrayList<ListModel> list) {
this.list = list;
notifyDataSetChanged();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
private final TextView todoText;
private final ImageView doneBtn;
private final ImageView notDoneBtn;
private final RelativeLayout listBlock;
public ViewHolder(@NonNull View itemView) {
super(itemView);
listBlock=itemView.findViewById(R.id.listBlock);
todoText = itemView.findViewById(R.id.todoText);
doneBtn = itemView.findViewById(R.id.doneBtn);
notDoneBtn = itemView.findViewById(R.id.notDoneBtn);
}
}
}
activity_main.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:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:background="@color/white"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="200dp"
android:layout_height="120dp"
android:layout_marginTop="4dp"
android:fontFamily="sans-serif-condensed"
android:gravity="center"
android:text="TO-DO LIST"
android:textSize="28sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.502"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</TextView>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintLayout3"
android:layout_width="300dp"
android:layout_height="480dp"
android:layout_marginTop="12dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView"
app:layout_constraintVertical_bias="0.0">
<ScrollView
android:layout_width="300dp"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.50">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="280dp"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="12dp">
</androidx.recyclerview.widget.RecyclerView>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintParentOfAddTodo"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginBottom="2dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/constraintLayout3"
app:layout_constraintVertical_bias="0.794">
<ImageView
android:id="@+id/addTodo"
android:layout_width="44dp"
android:layout_height="44dp"
android:layout_marginVertical="0dp"
android:backgroundTint="@color/white"
android:elevation="10dp"
android:src="@drawable/add_circle_48px"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.956"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</ImageView>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
list_template.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"
android:layout_height="42dp"
android:id="@+id/listBlock"
android:layout_width="280dp"
android:layout_gravity="center_horizontal">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_gravity="center_horizontal"
android:layout_marginTop="2dp"
android:layout_marginStart="1dp"
android:elevation="200dp"
app:cardBackgroundColor="#932"
app:cardCornerRadius="5dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/todoText"
android:layout_width="190dp"
android:layout_height="40dp"
android:layout_marginStart="10dp"
android:fontFamily="monospace"
android:gravity="center_vertical"
android:maxHeight="40dp"
android:padding="5dp"
android:text="Reading books"
android:textColor="#EFEBE9"
android:textSize="14sp"
android:textStyle="bold">
</TextView>
<ImageView
android:id="@+id/notDoneBtn"
android:layout_width="32dp"
android:layout_height="32dp"
android:layout_alignBottom="@id/todoText"
android:padding="5dp"
android:layout_marginStart="5dp"
android:layout_marginTop="4dp"
android:layout_marginBottom="4dp"
android:layout_toEndOf="@+id/todoText"
android:background="#999999"
android:src="@drawable/close_20px">
</ImageView>
<ImageView
android:id="@+id/doneBtn"
android:layout_width="32dp"
android:layout_height="32dp"
android:layout_marginStart="4dp"
android:layout_marginTop="5dp"
android:layout_marginBottom="4dp"
android:layout_toEndOf="@+id/notDoneBtn"
android:background="#999999"
android:padding="5dp"
android:src="@drawable/done_20px">
</ImageView>
</RelativeLayout>
</androidx.cardview.widget.CardView>
</RelativeLayout>
after_add_clicked.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">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginBottom="2dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent">
<com.google.android.material.card.MaterialCardView
android:id="@+id/materialCardView"
android:layout_width="310dp"
android:layout_height="match_parent"
android:layout_marginStart="50dp"
android:background="#121212"
android:backgroundTint="@color/white"
app:cardCornerRadius="30dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:strokeColor="#888"
app:strokeWidth="2dp">
<EditText
android:id="@+id/editTextTodo"
android:layout_width="300dp"
android:layout_height="40dp"
android:layout_gravity="center"
android:background="@color/white"
android:fontFamily="monospace"
android:gravity="center_vertical"
android:text="What to do"
android:inputType="text"
android:textSize="20sp">
</EditText>
</com.google.android.material.card.MaterialCardView>
<ImageView
android:id="@+id/sendTodo"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_margin="4dp"
android:layout_marginStart="4dp"
android:layout_marginTop="4dp"
android:layout_marginEnd="4dp"
android:layout_marginBottom="4dp"
android:src="@drawable/ic_baseline_send_24"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.529"
app:layout_constraintStart_toEndOf="@+id/materialCardView"
app:layout_constraintTop_toTopOf="parent">
</ImageView>
<ImageView
android:id="@+id/cancel"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_margin="4dp"
android:layout_marginStart="4dp"
android:layout_marginTop="4dp"
android:layout_marginEnd="4dp"
android:layout_marginBottom="4dp"
android:src="@drawable/close_20px"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/materialCardView"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</ImageView>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
如果您调用 addToList 来添加您的数据，所做的只是将一个新项目插入到您的 Activity 和适配器正在共享的列表中 - 适配器不知道有任何更改, 所以它不会更新显示
你应该在适配器上调用你的 setList 函数 - 用新列表替换当前列表（如果它实际上是同一个列表并不重要）然后调用 notifyDataSetChanged()显示“新”列表。
在你的适配器上有这样的功能总是更好 - 当你有新数据时，你只需将它传递给适配器，它可以在内部处理更新自身的细节。传递数据的东西不需要知道任何关于它的信息。如果你想稍后更新适配器的工作方式（比如更具体地更新某些项目，或者使用 DiffUtil），那么这仍然是一个内部细节——传递数据的东西只需要传递数据照常。
（你应该 setList 复制传入的列表，就像 list.toList() - 如果某些东西修改了原始列表，你不希望适配器的内部列表发生变化，这可能会导致错误。这里没问题，但是如果您使用 DiffUtil，例如，您的 oldList 也将是您的 newList，没有差异意味着没有更新）