Question

这里的问题是选择新类型后，用户向下滚动列表，然后向上备份，然后类型返回到更改前的类型。

这个问题可以总结如下：

微调框正在以某种方式保留先前的价值，并且设置
微调器的OnItemClicked函数在绑定时被调用到Spinner，这必须是Android Spinner中的错误对象，因为这不应该发生，而不是Spinner的方式在Android文档中进行了解释（https://developer.android.com/guide/topics/ui/controls/spinner）

例如，我有以下类型的列表：

输入“ X”
输入“ Y”
输入“ Z”

很抱歉，但是我可能应该包括整个实现。在诉诸于删除Spinner并使用其他操作之前，我正在寻找实现中的错误。

每当用户滚动并根据当前选定的项目进行更改时，都会调用setOnItemSelectedListener这个问题（我认为）。

我尝试了许多不同的解决方案；其中大多数都包含在here中。

但这不会引起我看到的问题，因为代码会查询数据库中的值；因此，如果用户选择新值时数据库中的值已更新，则应将该新值调用到微调器中，但不会。它总是叫旧的。

使用日志记录，我验证了在数据库中正确设置了新值，并在调用update之前和之后进行了记录。

    public class TypeFragment extends ListFragment implements AdapterView.OnItemClickListener {

    private static final String TAG = "TypeFragment";

    private TypeAdapter adapter;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState){
        View view = inflater.inflate(R.layout.fragment_type_list, container, false);

        SwipeRefreshLayout refreshLayout = view.findViewById(R.id.swiperefresh);
        refreshLayout.setOnRefreshListener(() -> {
            if(refreshLayout.isRefreshing()){
                refreshLayout.setRefreshing(false);
            }
        });

        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        List<dbRun> typesList = ExampleDatabase.getExampleDatabase().getTypeDao().getTypes();

        ArrayList<String> typeOptions = new ArrayList<>();
        typeOptions.add(getString(R.string.type_x));
        typeOptions.add(getString(R.string.type_y));
        typeOptions.add(getString(R.string.type_z));

        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(Objects.requireNonNull(getContext()),
                R.layout.support_simple_spinner_dropdown_item, typeOptions);

        adapter = new TypeAdapter(typesList, typeOptions, arrayAdapter);
        setListAdapter(adapter);
        adapter.notifyDataSetChanged();
        getListView().setOnItemClickListener(this);
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {}

    class TypeAdapter extends BaseAdapter {

        List<dbType> typesList;
        ArrayList<String> typeOptions;
        ArrayAdapter<String> arrayAdapter;

        public TypeAdapter(List<dbType> typesList, ArrayList<String> typeOptions, ArrayAdapter<String> arrayAdapter) {
            this.typesList = typesList;
            this.typeOptions = typeOptions;
            this.arrayAdapter = arrayAdapter;
        }

        public int getCount() {
            if (this.typesList != null) {
                return this.typesList.size();
            }
            return 0;
        }

        public Object getItem(int position) {
            return this.typesList.get(position);
        }

        public long getItemId(int position) {
            return this.typesList.get(position).id;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = LayoutInflater.from(getContext()).inflate(R.layout.types_row_layout, parent, false);
            }

            TextView typeTV = convertView.findViewById(R.id.type_tv_label);
            Spinner typeSpinner = convertView.findViewById(R.id.type_spinner);

            typeSpinner.setAdapter(this.arrayAdapter);

            dbType currentType = this.typesList.get(position);

            // here I ideally would set the Type to the one currently in the DB
            //typeSpinner.setSelection(arrayAdapter.getPosition(ExampleDatabase.getExampleDatabase().getTypeDao().getType(currentType.id));

            // most popular solution from StackOverflow questions:
            typeSpinner.setSelected(false);
            typeSpinner.setSelection(Adapter.NO_SELECTION, true);

            // set a spinner with its' listener on each row in the list
            typeSpinner.post(() -> typeSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> parent1, View view, int position1, long id) {
                    int item = typeSpinner.getSelectedItemPosition();
                    Log.d(TAG, "called onItemSelected, position " + position1 + " item: " + item);
                    ExampleDatabase.getExampleDatabase().getTypeDao().updateType(typeSpinner.get(item), currentType.id);
                    typeSpinner.setSelection(arrayAdapter.getPosition(arrayAdapter.getPosition(ExampleDatabase.getExampleDatabase().getTypeDao().getType(currentType.id)));
                }
                @Override
                public void onNothingSelected(AdapterView<?> parent1) {}
            }));

            return convertView;
        }
    }
}

数据库文件：

dbType ：

@Entity(tableName="types")
public class dbType {
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "id")
    public int id;

    @ColumnInfo(name = "type")
    public String type;

TypeDao ：

@Dao
public interface TypeDao {
    @Query("SELECT * FROM types;")
    List<dbType> getTypes();

    @Query("SELECT type FROM types WHERE id = :typeID;")
    String getType(int typeID);

    @Query("UPDATE types SET type = :typeStr WHERE id = :typeID;")
    void updateType(String typeStr, int typeID);

ExampleDatabase （为简洁起见，不包括迁移）

@Database(entities = {dbType.class})
@TypeConverters({dbTypeConverters.class})
public abstract class ExampleDatabase extends RoomDatabase {
    public abstract TypeDao getTypeDao()

    private static ExampleDatabase INSTANCE;

    public static CoriolisDatabase getCoriolisDatabase() {
        return INSTANCE;
    }

types_row_layout.xml ：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">

    <TextView
        android:id="@+id/type_tv_label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="16sp"
        android:padding="2dp"
        android:layout_marginLeft="2dp"
        android:layout_marginRight="2dp"
        android:layout_marginBottom="2dp"
        android:layout_marginTop="2dp"
        android:layout_gravity="center_vertical"
        android:text="@string/runs_list_runvolerror_column"
        app:layout_constraintStart_toEndOf="@id/netvolume_column"
        app:layout_constraintEnd_toStartOf="@id/run_info_btn"/>

    <android.support.constraint.Barrier
        android:id="@+id/barrier_run_row"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:barrierDirection="bottom"
        app:constraint_referenced_ids="netvolume_column, runvolerror_column"/>

    <Spinner
        android:id="@+id/type_spinner"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="start"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:ellipsize="end"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@id/run_info_btn"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/barrier_run_row" />


</android.support.constraint.ConstraintLayout>

编辑-以下是一些日志记录，用于验证数据库调用是否正常运行，因为在上面的主体中添加代码似乎会使代码的整体结构/格式混乱：

// before update check:
Log.d(TAG, "DB type before updating: type ID is " + currentType.id + ", type is " + ExampleDatabase.getExampleDatabase().getTypeDao().getTypeWithID(currentType.id).type);
// update happens
Log.d(TAG, "DB type after updating: type ID is " + currentType.id + ", type is " + ExampleDatabase.getExampleDatabase().getTypeDao().getTypeWithID(currentType.id).type);

此日志记录表明滚动时类型已更改，并且数据库更新卡住了。

初次滚动时的输出（注意未单击时如何调用，并以相同的值进行更新）：

DB type before updating: type ID is 57, type is Type X
DB type after updating: type ID is 57, type is Type X

同样，在点击并更改值为类型Y后，

DB type before updating: type ID is 57, type is Type X
DB type after updating: type ID is 57, type is Type Y

看起来它更新得很好...

然后，再次滚动实际更新它（注意它如何从以前恢复为Type X）：

DB type before updating: type ID is 57, type is Type Y
DB type after updating: type ID is 57, type is Type X

微调框setOnItemSelectedListener无法与Room DB调用一起正常使用

0 个答案: