Question

抱歉我的英语不好，还有一个愚蠢的菜鸟问题。我有一个SimpleCursorAdapter和每个项目上的按钮ListView（数据库中的行）我意识到删除行但我不知道如何刷新ListView 我希望有人能用简单明了的例子来帮助我

我的适配器

public class MySimpleCursorAdapter extends SimpleCursorAdapter {

Context context;

public MySimpleCursorAdapter(Context contxt, int layout, Cursor c, String[] from, int[] to, int flags) {
    super(contxt, layout, c, from, to, flags);
    context=contxt;

}

public View newView(Context _context, Cursor _cursor, ViewGroup parent){
    LayoutInflater inflater = (LayoutInflater) _context.getSystemService(_context.LAYOUT_INFLATER_SERVICE);
    View view = inflater.inflate(R.layout.listform_item, parent, false);
    return view;
}

@Override
public void bindView(View view,  Context Context,  Cursor cursor) {
    String name = cursor.getString(cursor.getColumnIndex(DBHelper.FORM_NAME));
    String title = cursor.getString(cursor.getColumnIndex(DBHelper.FORM_TITLE));
    TextView formname = (TextView)view.findViewById(R.id.tvFormName);
    formname.setText(name);
    TextView formtitle=(TextView)view.findViewById(R.id.tvFormTitle);
    formtitle.setText(title);
    ImageButton yourButton = (ImageButton)view.findViewById(R.id.ibtnDelete);
    yourButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if(view != null) {
                Object obj = view.getTag();
                //if(obj != null && obj instanceof Integer) {
                dbForm form=new dbForm(context);
                form.open();
                String st=obj.toString();
                form.deleteForm(Long.valueOf(st).longValue());
                    Toast.makeText(context, "Delete row with id = " + st, Toast.LENGTH_LONG).show();


            }
        }
    });
    Object obj = cursor.getString(cursor.getColumnIndex(DBHelper.FORM_ID));
    yourButton.setTag(obj);


}
}

我还在Main中使用CursorLoader来访问数据库

UPD：我使用游标加载器而不是如何在我的自定义适配器中调用他的重置，希望得到帮助。

public class MainActivity extends FragmentActivity implements LoaderCallbacks<Cursor> {

ListView lvForms;
dbForm table_form;
SimpleCursorAdapter scAdapter;

/**
 * Called when the activity is first created.
 */
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    table_form = new dbForm(this);
    table_form.open();


    String[] from = new String[]{DBHelper.FORM_NAME, DBHelper.FORM_TITLE};
    int[] to = new int[]{R.id.tvFormName, R.id.tvFormTitle};


    scAdapter = new MySimpleCursorAdapter(this, R.layout.listform_item, null, from, to, 0);
    lvForms = (ListView) findViewById(R.id.lvForms);
    lvForms.setAdapter(scAdapter);


    registerForContextMenu(lvForms);


    getSupportLoaderManager().initLoader(0, null, this);
}


public void onButtonClick(View view) {
    Intent intent = new Intent(MainActivity.this, LoginActivity.class);
    startActivity(intent);
}


protected void onDestroy() {
    super.onDestroy();
    table_form.close();
    // закрываем подключение при выходе
}

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle bndl) {
    return new MyCursorLoader(this, table_form);
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    scAdapter.swapCursor(cursor);
}

@Override
public void onLoaderReset(Loader<Cursor> loader) {
    scAdapter.swapCursor(null);
}

static class MyCursorLoader extends CursorLoader {

    dbForm table_form;

    public MyCursorLoader(Context context, dbForm table_form) {
        super(context);
        this.table_form = table_form;
    }

    @Override
    public Cursor loadInBackground() {
        Cursor cursor = table_form.getAllData();
        return cursor;
    }

}

}

Answer 1

对于SimpleCursorAdapter，最好使用像这样的CursorLoader：

    public Loader<Cursor> onCreateLoader(int id,Bundle arg) {
    return new SimpleCursorLoader(this) {
        public Cursor loadInBackground() {
            // This field reserved to what you want to load in your cursor adater and you return it (for example database query result)
            // return Cursor ;
        }
    };
}

public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    adapter.swapCursor(cursor);    
}

public void onLoaderReset(Loader<Cursor> loader){
    adapter.swapCursor(null);
}

在您的MainActivity中或您将实现适配器的位置，就在添加之前：

getLoaderManager().initLoader(0x01, null, this);
// declare your new Custom Simple Cursor Adapter here
scAdapter = new MySimpleCursorAdapter ....

并添加：

    public void onResume() {
    super.onResume();
    // Restart loader so that it refreshes displayed items according to database
    getLoaderManager().restartLoader(0x01, null, this);
}

我以这种方式与装载机一起工作，我希望它可以帮到你。

Answer 2

您应该重新加载光标并更新光标适配器：

// Reload your cursor here
Cursor newCursor = ….;

if (android.os.Build.VERSION.SDK_INT > android.os.Build.VERSION_CODES.GINGERBREAD){
    adapter.swapCursor(newCurosr);
} else {
    adapter.changeCursor(newCursor);
}

然后，通知列表视图有关数据更改的信息：

adapter.notifyDataSetChanged();

删除数据库行后刷新自定义游标适配器

2 个答案: