如何更新列表视图

Question

  Cursor smCursor = getContentResolver().query( 
            Uri.parse("content://contact"),
            new String[] { "_id", "address", "body" }, "address like?",
            new String[] { searchContactPhone }, null); 
CustomAdapter ada = new CustomAdapter(this,
                R.layout.sm_layout, smCursor, new String[] {
                        "body" }, new int[] {
                        R.id.txt2 });
        lvSm.setAdapter(ada);

btnDel.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {


            ArrayList<Boolean> ca = ada.getItemsThatAreChecked();
            // this ArrayList will hold our Strings from the rows that were clicked.
            ArrayList<String> results = new ArrayList<String>();
            int s = ca.size();
            for (int i = 0; i < s; i++) {
                    if (ca.get(i).booleanValue()) {
                            smCursor.moveToPosition(i);
                            Log.v("sss", smCursor.getString(smCursor.getColumnIndex("_id")));
                            results.add(smCursor.getString(smCursor.getColumnIndex("_id")));
                    }
            }
            if(results != null && !results.isEmpty()){
                String [] mSelectionArgs  = results.toArray(new String[results.size()]);
                String mSelectionClause = "_id=?";
                int delCursor = 0;

                Uri uri = Uri.parse("content://contact");
                for(int delCount = 0;delCount < mSelectionArgs.length;delCount++)
                {
                delCursor = getContentResolver().delete(uri ,mSelectionClause,new String[]{mSelectionArgs[delCount]});
                }
                ada.notifyDataSetChanged();
                Toast.makeText(getApplicationContext(), mSelectionArgs.length +" number of rows deleted", 5).show();

            }
            else
                Toast.makeText(getApplicationContext(), "Sorry no deletion occurs", 5).show();


        }

我想知道如何更新我的列表视图，因为我从列表视图中删除所选项目，删除后选择自动发生在下一个项目。我使用了notifyDataSetChanged（）但不起作用。我正在使用自定义适配器。

Answer 1

要在删除后使其工作，您需要在调用notifyDataSetChanged方法之前更改数据源，这可以通过smCursor.requery（）实现;方法，但作为其弃用的方法，我建议再次执行查询，所以单击删除按钮时的代码块应该是：

btnDel.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {


            ArrayList<Boolean> ca = ada.getItemsThatAreChecked();
            // this ArrayList will hold our Strings from the rows that were clicked.
            ArrayList<String> results = new ArrayList<String>();
            int s = ca.size();
            for (int i = 0; i < s; i++) {
                    if (ca.get(i).booleanValue()) {
                            smCursor.moveToPosition(i);
                            Log.v("sss", smCursor.getString(smCursor.getColumnIndex("_id")));
                            results.add(smCursor.getString(smCursor.getColumnIndex("_id")));
                    }
            }
            if(results != null && !results.isEmpty()){
                String [] mSelectionArgs  = results.toArray(new String[results.size()]);
                String mSelectionClause = "_id=?";
                int delCursor = 0;

                Uri uri = Uri.parse("content://contact");
                for(int delCount = 0;delCount < mSelectionArgs.length;delCount++)
                {
                delCursor = getContentResolver().delete(uri ,mSelectionClause,new String[]{mSelectionArgs[delCount]});
                }


            smCursor = getContentResolver().query( 
            Uri.parse("content://contact"),
            new String[] { "_id", "address", "body" }, "address like?",
            new String[] { searchContactPhone }, null); 
                ada.notifyDataSetChanged();
                Toast.makeText(getApplicationContext(), mSelectionArgs.length +" number of rows deleted", 5).show();

            }
            else
                Toast.makeText(getApplicationContext(), "Sorry no deletion occurs", 5).show();


        }

Answer 2

btnDel.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {


            ArrayList<Boolean> ca = ada.getItemsThatAreChecked();
            // this ArrayList will hold our Strings from the rows that were clicked.
            ArrayList<String> results = new ArrayList<String>();
            int s = ca.size();
            for (int i = 0; i < s; i++) {
                    if (ca.get(i).booleanValue()) {
                            smCursor.moveToPosition(i);
                            Log.v("sss", smCursor.getString(smCursor.getColumnIndex("_id")));
                            results.add(smCursor.getString(smCursor.getColumnIndex("_id")));
                    }
            }
            if(results != null && !results.isEmpty()){
                String [] mSelectionArgs  = results.toArray(new String[results.size()]);
                String mSelectionClause = "_id=?";
                int delCursor = 0;

                Uri uri = Uri.parse("content://contact");
                for(int delCount = 0;delCount < mSelectionArgs.length;delCount++)
                {
                delCursor = getContentResolver().delete(uri ,mSelectionClause,new String[]{mSelectionArgs[delCount]});
                }
        ada = new CustomAdapter(this,
                R.layout.sm_layout, smCursor, new String[] {
                        "body" }, new int[] {
                        R.id.txt2 });
        lvSm.setAdapter(ada);

                Toast.makeText(getApplicationContext(), mSelectionArgs.length +" number of rows deleted", 5).show();

            }
            else
                Toast.makeText(getApplicationContext(), "Sorry no deletion occurs", 5).show();


        }

工作正常，因为我只重新创建自定义适配器的实例，并在删除后将其绑定到列表视图。