【发布时间】：2014-11-26 11:52:28
【问题描述】：
我想从 Listview 中删除一个项目，并在删除一个项目后一次刷新 Listview。怎么可能？
我正在使用 JSON 解析从数据库中获取所有项目，并在单击按钮时删除选定的项目。从数据库中成功删除，但 Listview 一次不刷新。怎么办？
我正在使用 Json 解析。不是本地数据库。
在这种情况下，如何在删除项目时刷新Listview？ 请指导我。 提前致谢。
我的代码是， Detail.java 文件
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);
}
}
}
}
适配器类是， Adapter1.java 文件
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 文件是，
<?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 文件是，
<?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>
【问题讨论】：
-
使用 adapter.notifyDataSetChanged();
-
在您的自定义适配器中调用 this.notifyDataSetChanged();您正在执行删除功能并从设置为该适配器的 arrayList 中删除该元素
-
@Shrinivas 请在我的代码中更新，因为此代码在剩余的 Listview Refresh 中成功运行...我的代码在哪里更新。
-
你用过adapter.notifyDataSetChanged();吗？
-
@Reena 只需在
postexecute中添加notifyDataSetChanged()。