Android

Question

我正在尝试基于 Switch 更新数据库 table 中的布尔值。 ListView 包含一个语言列表，每个语言都有一个 "Install" 切换按钮。我的 CursorAdapter 正在显示列表和开关。我为每个 Switch 设置了 OnCheckedChangeListeners。当我 select 其中一个开关时，它短暂地显示它已打开，但立即恢复为 "off." 在我的日志记录中，我看到该值设置为 "true" 并且这被发送到 DatabaseProvider 以更新数据库。但紧接着，我看到另一个日志输出，该值为 false，然后在另一个更新中发送到 DatabaseProvider。

游标适配器：

public static class ViewHolder {
    public final TextView nameView;
    public final Switch installSwitch;

    public ViewHolder(View view) {
        nameView = (TextView) view.findViewById(R.id.language_textview);
        installSwitch = (Switch) view.findViewById(R.id.installed_switch);
    }
}

public LanguageAdapter(Context context, Cursor c, int flags) {
    super(context, c, flags);
}

@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
    View view = LayoutInflater.from(context).inflate(R.layout.list_item_language, parent, false);
    ViewHolder viewHolder = new ViewHolder(view);
    view.setTag(viewHolder);
    return view;
}

@Override
public void bindView(View view, Context context, final Cursor cursor) {

    ViewHolder viewHolder = (ViewHolder) view.getTag();
    long languageId = cursor.getLong(0);
    String word = cursor.getString(1);
    boolean langInstalled = Boolean.parseBoolean(cursor.getString(2));
    viewHolder.nameView.setText(word);
    viewHolder.installSwitch.setChecked(langInstalled);
    viewHolder.installSwitch.setTag(languageId);

    viewHolder.installSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            long languageId = (long) buttonView.getTag();
            ContentValues cv = new ContentValues();
            cv.put(TranslationContract.LanguageEntry.COLUMN_INSTALLED, isChecked);
            Log.d(LOG_TAG, "onChecked, langID: " + languageId + " isChecked: " + isChecked);
            buttonView.getContext().getContentResolver().update(TranslationContract.LanguageEntry.CONTENT_URI, cv, TranslationContract.LanguageEntry._ID+"=?", new String[] {String.valueOf(languageId)});
       }
    });
}

数据库提供者：

public int update(
        Uri uri, ContentValues values, String selection, String[] selectionArgs) {
    final SQLiteDatabase db = mOpenHelper.getWritableDatabase();
    final int match = sUriMatcher.match(uri);
    int rowsUpdated;

    switch (match) {
        case LANGUAGES:
            rowsUpdated = db.update(LanguageEntry.TABLE_NAME, values, selection,
                    selectionArgs);
            Log.d(LOG_TAG, "Updating languages: " + values.toString());
            break;
 }

日志：

07-13 21:39:32.785    LanguageAdapter﹕ onChecked, langID: 2 isChecked: true
07-13 21:39:32.800    DatabaseProvider﹕ Updating languages: installed=true
07-13 21:39:32.813    LanguageAdapter﹕ onChecked, langID: 2 isChecked: false
07-13 21:39:32.825    DatabaseProvider﹕ Updating languages: installed=false

Answer 1

经过深入挖掘，我发现了两个问题：

首先，onCheckChanged 似乎总是被调用两次，这可能是一个 android 错误？请参阅以下帖子： onCheckedChanged fired multiple times, Listview with checkbox 和 CheckBox changes value twice

改为使用 onClickListener。

这里的第二个问题是数据库游标和 java 代码之间的布尔值处理不正确。 SQLite 没有本机 BOOLEAN 类型，因此值以整数 0 或 1 的形式存储和返回。需要对它们进行评估，然后将其转换为 java 布尔值。

更正后的代码为：

@Override
public void bindView(View view, Context context, final Cursor cursor) {

    ViewHolder viewHolder = (ViewHolder) view.getTag();
    long languageId = cursor.getLong(0);
    String word = cursor.getString(1);
    boolean langInstalled = cursor.getInt(2)>0; //convert DB 1 or 0 to java boolean
    viewHolder.nameView.setText(word);
    viewHolder.installSwitch.setChecked(langInstalled);
    viewHolder.installSwitch.setTag(languageId);
    viewHolder.installSwitch.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            CompoundButton button = (CompoundButton) v;
            long languageId = (long) button.getTag();
            boolean isChecked = button.isChecked();
            int dbBoolean = 0;
            if (button.isChecked()) {
                dbBoolean = 1;
            }
            ContentValues cv = new ContentValues();
            cv.put(TranslationContract.LanguageEntry.COLUMN_INSTALLED, dbBoolean);
            button.getContext().getContentResolver().update(TranslationContract.LanguageEntry.CONTENT_URI, cv, TranslationContract.LanguageEntry._ID + "=?", new String[]{String.valueOf(languageId)});
            notifyDataSetChanged();
        }
    });
}

Android - 为什么 CursorAdaptor 上的切换按钮会在更改后立即重置按钮

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android-cursoradapter