android中删除按钮单击事件中的项目后如何刷新Listview？

Question

I want to delete an item from Listview, and at a time Refresh Listview after deleting an item. How to possible?

I am using get all item using JSON Parsing from database and delete an selected an item on click of button. delete successfully from database but Listview not refresh at a time. how to do?

I am using Json Parsing. not local database.

In This case, How to refresh Listview when Deleting Item? please Guide me. Thanks in Advance.

My Code is, Detail.java File

public class Detail extends Activity {
    ListView lstDetail = null;
    /** String */
    String urlGetDetailData = null;

    /** Declare another variable for Listview */
    Adapter1 adapter1 = null;
    ArrayList<Detail> myList = new ArrayList<Detail>();
    /** Hashmap for ListView */
    ArrayList<HashMap<String, String>> dataList = null;

    /** JSON Node names */
    public static final String TAG_MEMBER_ID = "mem_id";
    public static final String TAG_ID = "id";
    public static final String TAG_USER_ID = "userid";
    public static final String TAG_STATUS = "Status";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        onCreateActivity(R.layout.detail);

        initializeWidgets();
    }

    private void initializeWidgets() {
        /** ListView */
        lstDetail = (ListView) findViewById(R.id.lstDetail);

        urlGetDetailData = "http://example.com/getdata.php?id="
                + strId;

        new GetDetailData().execute();
        myList.remove(position);
        Adapter1.this.notifyDataSetChanged();

    }

    /**
     * Async task class to get json by making HTTP call
     * */
    private class GetDetailData extends AsyncTask<Void, Void, Void> {
        JSONObject jsonobject;
        JSONArray jsonarray;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... arg0) {
            dataList = new ArrayList<HashMap<String, String>>();
            // Retrieve JSON Objects from the given URL address
            jsonobject = JSONFunctions.getJSONfromURL(urlGetDetailData);

            try {
                // Locate the array name in JSON
                jsonarray = jsonobject.getJSONArray("data");

                for (int i = 0; i < jsonarray.length(); i++) {

                    HashMap<String, String> map = new HashMap<String, String>();
                    jsonobject = jsonarray.getJSONObject(i);
                    // Retrive JSON Objects

                    map.put("mem_id", String.valueOf(jsonobject
                            .getString(TAG_MEMBER_ID)));
                    map.put("id",
                            jsonobject.getString(TAG_ID));

                    map.put("userid", jsonobject.getString(TAG_USER_ID));
                    map.put("Status", jsonobject.getString(TAG_STATUS));

                    dataList.add(map);
                }
            } catch (JSONException e) {
                Log.e("Error", e.getMessage());
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            if (dataList.size() != 0) {
                lstDetail.setVisibility(View.VISIBLE);
                Adapter1 = new Adapter1(Detail.this,
                        dataList);
                lstDetail.setAdapter(Adapter1);
            } else {
                lstDetail.setVisibility(View.GONE);
            }
        }
    }
}

And Adapter Class is, Adapter1.java File

public class Adapter1 extends BaseAdapter {
    public ArrayList<HashMap<String, String>> arrData = null;
    Context context = null;
    LayoutInflater layoutInflater = null;
    HashMap<String, String> getDetailData = new HashMap<String, String>();

    /** String */
    String strMemberId = null, urlDelete = null;

    /** Constructor */
    public Adapter1(Context context,
            ArrayList<HashMap<String, String>> arrData) {
        layoutInflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        this.context = context;
        this.arrData  = arrData;
    }

    @Override
    public int getCount() {
        return arrData.size();
    }

    @Override
    public Object getItem(int position) {
        return arrData.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            convertView = layoutInflater.inflate(
                    R.layout.list_item, null);

            viewHolder = new ViewHolder();
            getData = arrData.get(position);

            /** Initialize Widgets */

            viewHolder.imgCancel = (ImageView) convertView
                    .findViewById(R.id.imgCancel);

            viewHolder.imgCancel
                    .setOnClickListener(new OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            strMemberId = arrData.get(
                                    position).get(
                                    Detail.TAG_MEMBER_ID);
                            urlDelete = "http://example.com/delete.php?mem_id="
                                    + strMemberId;
                            new DeleteComments().execute();
                        }
                    });

            /** TextView */
            viewHolder.txtMemberId = (TextView) convertView
                    .findViewById(R.id.txtMemberId);
            viewHolder.txtId = (TextView) convertView
                    .findViewById(R.id.txtId);

            viewHolder.txtDesc = (TextView) convertView
                    .findViewById(R.id.txtDesc);

            /** Set Value */


            viewHolder.txtMemberId.setText(getDetailData 
                    .get(Detail.TAG_MEMBER_ID));
            viewHolder.txtId.setText(getDetailData
                    .get(Detail.TAG_ID));

            viewHolder.txtDesc.setText(getDetailData
                    .get(Detail.TAG_STATUS));

            convertView.setTag(viewHolder);

        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        return convertView;
    }

    /** ViewHolder Class */
    @SuppressLint("NewApi")
    public static class ViewHolder {
        ImageView imgCancel = null;
        TextView txtMemberId = null, txtId = null,txtDesc = null;
    }

    public class DeleteComments extends AsyncTask<Void, Void, Void> {
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... arg0) {
            ServiceHandler sh = new ServiceHandler();
            String jsonStr = sh.makeServiceCall(urlDelete,
                    ServiceHandler.GET);
            Log.d("Response : delete join comments", ">" + jsonStr);

            return null;
        }

        protected void onPostExecute(Void result) {
            super.onPostExecute(result);

        };
    }
}

detail.xml File is,

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/re/android"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content" >

    <ListView
        android:id="@+id/lstDetail"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >
    </ListView>
</RelativeLayout>

list_item.xml file is,

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/re/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" >

    <LinearLayout
        android:id="@+id/contentLayout"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/txtId"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="111" />

        <TextView
            android:id="@+id/txtDesc"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <ImageView
        android:id="@+id/imgCancel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:src="@drawable/cancel" />

    <TextView
        android:id="@+id/txtMemberId"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/txtUserEventId"
        android:layout_alignBottom="@+id/txtUserEventId"
        android:layout_alignParentLeft="true"
        android:text="222" />
</RelativeLayout>

Answer 1

in your custom adapter call this.notifyDataSetChanged(); where you are performing delete functionality and deleting that element from arrayList which is set to that adapter

Answer 2

您正在编写删除操作，在该函数中，仅再次调用adapter.notifyDataSetChanged。因此，它在删除操作时再次取回数据，然后再次调用adapter.notifyDataSetChanged它将起作用

Answer 3

First of all Put you adapter code in Details.java class

then change this,

public class DeleteComments extends AsyncTask<Void, Void, Void> {
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... arg0) {
            ServiceHandler sh = new ServiceHandler();
            String jsonStr = sh.makeServiceCall(urlDelete,
                    ServiceHandler.GET);
            Log.d("Response : delete join comments", ">" + jsonStr);

            return null;
        }

        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            Adapter1.remove(Adapter1.getItem(position));
        };
    }

hope it will help you

Answer 4

     @Override
        public View getView(final int position, View convertView, ViewGroup parent) {
            ViewHolder viewHolder = null;
            if (convertView == null) {
                convertView = layoutInflater.inflate(
                        R.layout.list_item, null);

                viewHolder = new ViewHolder();
                getData = arrData.get(position);

                /** Initialize Widgets */

                viewHolder.imgCancel = (ImageView) convertView
                        .findViewById(R.id.imgCancel);

                viewHolder.imgCancel
                        .setOnClickListener(new OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                strMemberId = arrData.get(
                                        position).get(
                                        Detail.TAG_MEMBER_ID);
                                urlDelete = "http://example.com/delete.php?mem_id="
                                        + strMemberId;
                                new DeleteComments().execute();
                            }
                        });

                /** TextView */
                viewHolder.txtMemberId = (TextView) convertView
                        .findViewById(R.id.txtMemberId);
                viewHolder.txtId = (TextView) convertView
                        .findViewById(R.id.txtId);

                viewHolder.txtDesc = (TextView) convertView
                        .findViewById(R.id.txtDesc);

                /** Set Value */


                viewHolder.txtMemberId.setText(getDetailData 
                        .get(Detail.TAG_MEMBER_ID));
                viewHolder.txtId.setText(getDetailData
                        .get(Detail.TAG_ID));

                viewHolder.txtDesc.setText(getDetailData
                        .get(Detail.TAG_STATUS));

                convertView.setTag(viewHolder);

            } else {
                viewHolder = (ViewHolder) convertView.getTag();
            }
bDelete.setOnClickListener(new OnClickListener(){
@Override
            public void onClick(View view)
            {
                arrData.remove(position);
                notifyDataSetChanged():
            }

});


            return convertView;
        }

Answer 5

Why make it that complicated?

Just call remove(Obj); in OnClickListener of your customized adapter Adapter1 's. And notifyDataSetChanged will be called in removed method too.