我有ListView和我自己的适配器。 ListView项由TextView，图标图像和图像“垃圾箱”（简称“垃圾箱”）组成。问题是，当我单击任何项目时，应将其删除，但实际上ListView的最后一项消失了。我检查了ArrayList，并从中删除了我单击的项目。另外，当我尝试添加新项目时，该程序仅恢复先前的项目，并且如果显示所有初始项目，并且我尝试添加新程序，则程序崩溃。尽管已在ArrayList中正确添加了项目。
活动代码
public class MyItemsActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_items);
myItemsList = findViewById(R.id.ListOfMyItems);
myItemsAdapter.arrayList.add(new MyItems("Keys", R.drawable.plus));
myItemsAdapter.arrayList.add(new MyItems("Wallet", R.drawable.plus));
myItemsAdapter.arrayList.add(new MyItems("Physics", R.drawable.plus));
myItemsAdapter.arrayList.add(new MyItems("umovnyy vasyl", R.drawable.plus));
myItemsAdapter.arrayList.add(new MyItems("Smartphone)", R.drawable.plus));
for (int i = 0; i<100; i++){
arrayList.add(new MyItems("Max)", R.drawable.plus));
}
myItemsList.addFooterView(new ImageView(this));
myItemsList.addHeaderView(new ImageView(this));
myItemsList.setAdapter(myItemsAdapter);
for (int i = 0; i<100; i++){
myItemsAdapter.arrayList.remove((5));
}
arrayList.add(new MyItems("Maxx)", R.drawable.plus));
myItemsAdapter.notifyDataSetChanged();
myItemsAdapter.notifyDataSetInvalidated();
myItemsList.setOnItemClickListener((parent, view, position, id) -> {
Toast.makeText(getApplicationContext(),
"Click ListItem Number " + position, Toast.LENGTH_SHORT)
.show();
myItemsAdapter.arrayList.remove((position-1));
myItemsAdapter.notifyDataSetChanged();
myItemsList.invalidateViews();
myItemsAdapter.notifyDataSetInvalidated();
});
}
ListView myItemsList;
ArrayList<MyItems> arrayList = new ArrayList<>();
MyItemsAdapter myItemsAdapter = new MyItemsAdapter(MyItemsActivity.this, arrayList);
public void addNewItem(View view) {
AlertDialog.Builder dialog = new AlertDialog.Builder(MyItemsActivity.this);
dialog.setView(R.layout.add_new_item);
AlertDialog alertDialog = dialog.create();
ListView a = alertDialog.getListView();
alertDialog.show();
myItemsList.invalidateViews();
}
public void addNewItemButtonClicked(View view){
LayoutInflater inflater = getLayoutInflater();
View v = inflater.inflate(R.layout.add_new_item, null);
EditText nameOfItem = v.findViewById(R.id.nameOfItem);
arrayList.add(new MyItems(nameOfItem.getText().toString(), R.drawable.forwardbutton));
myItemsAdapter.notifyDataSetChanged();
myItemsAdapter.notifyDataSetInvalidated();
}
public void notificationClicked(View view){
Toast.makeText(getApplicationContext(),
"Notification clicked", Toast.LENGTH_SHORT)
.show();
}
public void openMenu(View view) {
Intent intent = new Intent(getBaseContext(), MenuActivity.class);
startActivity(intent);
}
}
适配器
class MyItemsAdapter extends BaseAdapter {
ArrayList<MyItems> arrayList;
Context context;
public MyItemsAdapter(Context context, ArrayList<MyItems> arrayList) {
this.arrayList=arrayList;
this.context=context;
}
@Override
public boolean areAllItemsEnabled() {
return false;
}
@Override
public boolean isEnabled(int position) {
return true;
}
@Override
public void registerDataSetObserver(DataSetObserver observer) {
observer.onChanged();
super.registerDataSetObserver(observer);
}
@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
super.unregisterDataSetObserver(observer);
observer.onInvalidated();
}
@Override
public int getCount() {
return arrayList.size();
}
@Override
public MyItems getItem(int position) {
return arrayList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
final MyItems myItems = arrayList.get(position);
if(convertView == null) {
LayoutInflater layoutInflater = LayoutInflater.from(context);
convertView = layoutInflater.inflate(R.layout.example_of_list_of_items, parent, false);
TextView nameOfItem = convertView.findViewById(R.id.exampleTextView);
ImageView itemCircle = convertView.findViewById(R.id.exampleImageViewIcon);
ImageView trash = convertView.findViewById(R.id.exampleImageViewTrash);
nameOfItem.setText(myItems.itemName);
itemCircle.setImageResource(myItems.itemImage);
trash.setImageResource(R.drawable.trash);
trash.setOnClickListener(v -> {
Toast.makeText(context, "lol "+position, Toast.LENGTH_SHORT).show();
arrayList.remove(position);
notifyDataSetChanged();
notifyDataSetInvalidated();
});
}
return convertView;
}
@Override
public int getItemViewType(int position) {
return position;
}
@Override
public int getViewTypeCount() {
return arrayList.size();
}
@Override
public boolean isEmpty() {
return false;
}
}
MyItems代码
class MyItems {
String itemName;
int itemImage;
public MyItems(String itemName, int image) {
this.itemName = itemName;
this.itemImage = image;
}
}
项目示例
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/exampleTextView"
android:layout_width="170dp"
android:layout_height="wrap_content"
android:layout_marginStart="30dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="85dp"
android:fadingEdge="horizontal|vertical"
android:layoutDirection="inherit"
android:lineSpacingExtra="14sp"
android:text="TextView"
android:textAlignment="textStart"
android:textColor="#000000"
android:textSize="20sp"
app:autoSizeMaxTextSize="20sp"
app:autoSizeMinTextSize="8sp"
app:layout_constraintEnd_toStartOf="@+id/exampleImageViewTrash"
app:layout_constraintStart_toEndOf="@+id/exampleImageViewLeft"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="@+id/exampleImageViewLeft"
android:layout_width="25dp"
android:layout_height="23dp"
android:layout_marginStart="32dp"
android:layout_marginTop="24dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@mipmap/ic_launcher_round" />
<ImageView
android:id="@+id/exampleImageViewTrash"
android:layout_width="49dp"
android:layout_height="47dp"
android:layout_marginTop="12dp"
android:layout_marginEnd="20dp"
android:cropToPadding="true"
android:fitsSystemWindows="true"
android:focusableInTouchMode="false"
android:focusable="false"
android:clickable="false"
android:scaleType="centerInside"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/trash" />
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideline2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintGuide_begin="70dp"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
主屏幕代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="99dp">
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintGuide_begin="127dp"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:id="@+id/myItemsTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/my_items"
android:textColor="#000000"
android:textSize="36sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="@+id/menuImageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="20dp"
android:clickable="true"
android:focusable="true"
android:onClick="openMenu"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/menu" />
<ImageView
android:id="@+id/notificationImageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:clickable="true"
android:focusable="true"
android:onClick="notificationClicked"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/notification" />
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="@+id/ListOfMyItems"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_marginStart="1dp"
android:layout_marginTop="30dp"
android:layout_marginEnd="1dp"
android:layout_marginBottom="100dp"
android:alwaysDrawnWithCache="true"
android:animateLayoutChanges="true"
android:choiceMode="singleChoice"
android:clickable="false"
android:clipToPadding="false"
android:descendantFocusability="beforeDescendants"
android:dividerHeight="1dp"
android:footerDividersEnabled="true"
android:headerDividersEnabled="true"
android:isScrollContainer="true"
android:layoutDirection="ltr"
android:scrollbars="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0"
tools:listfooter="@android:layout/simple_list_item_1">
</ListView>
<LinearLayout
android:layout_width="409dp"
android:layout_height="70dp"
android:layout_marginStart="1dp"
android:layout_marginTop="1dp"
android:layout_marginEnd="1dp"
android:focusable="auto"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/ListOfMyItems">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clickable="true"
android:focusable="true">
<TextView
android:id="@+id/addNewItemTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="-1dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="70dp"
android:clickable="true"
android:focusable="true"
android:onClick="addNewItem"
android:text="@string/add_new_item"
android:textColor="#000000"
android:textSize="30sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/plusImageView"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="@+id/plusImageView"
android:layout_width="67dp"
android:layout_height="74dp"
android:layout_marginStart="56dp"
android:clickable="false"
android:focusable="true"
android:onClick="addNewItem"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/plus" />
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
AlertDialog添加新项目的代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="300dp"
android:orientation="vertical">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="300dp"
android:background="#FFFFFF">
<EditText
android:id="@+id/nameOfItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="100dp"
android:ems="10"
android:hint="Enter name"
android:inputType="textPersonName"
android:singleLine="true"
android:textColor="#000000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="48dp"
android:layout_marginTop="9dp"
android:background="@android:drawable/btn_default_small"
android:onClick="addNewItemButtonClicked"
android:text="Button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/nameOfItem" />
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
好像您的数据未在Adapter的getView方法中正确更新。当contentView不为null时，您应该尝试更新适配器内的项目。出于性能原因，适配器内部使用了一种称为ViewHolder的模式。有关更多信息，请参见Android listview using ViewHolder。只需在contentView为null时创建Holder，然后在不设置时设置数据。希望对您有所帮助。
P.S。 ListView被认为已弃用。请改用RecyclerView。它已经内置了ViewHolder模式，并且更加灵活]]