我试图更改android listview中的图像视图。如果我已经从列表中选择了任何项目行。，有两张图片。它们是出席的，不出席的。
默认情况下，项目状态为出席。如果用户点击出席图像。，功能完成后，需要将出席图像更改为取消出席。
如果用户点击了未显示的图像。，则需要将未出席的图像更改为出席的图像来完成功能。
我遵循以下代码。功能运行良好。但图像在运行时没有改变。请检查代码并给我一个解决方案。
public class Today_List_Adapter extends BaseAdapter {
private Activity activity;
static ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
AlertDialog.Builder alertDialog;
public ImageLoader imageLoader;
String success,error;
JSONParser jsonParser = new JSONParser();
public Today_List_Adapter(Activity a, ArrayList<HashMap<String, String>> d) {
activity = a;
data=d;
inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
return data.size();
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
View vi=convertView;
if(convertView==null)
vi = inflater.inflate(R.layout.listof_today, null);
TextView cartitle = (TextView)vi.findViewById(R.id.today_producttitle);
ImageView carimage = (ImageView)vi.findViewById(R.id.today_productimage);
TextView cardate = (TextView)vi.findViewById(R.id.today_productdate);
TextView cartime = (TextView)vi.findViewById(R.id.today_producttime);
TextView carddesc = (TextView)vi.findViewById(R.id.today_productdesc);
final ImageView cardetails = (ImageView)vi.findViewById(R.id.today_productimage_detail);
ImageView carcheckin = (ImageView)vi.findViewById(R.id.today_productimage_attend);
HashMap<String, String> Order = new HashMap<String, String>();
Order = data.get(position);
cartitle.setText(Order.get(TodayList.TAG_CAR_TITLE));
cardate.setText(Order.get(TodayList.TAG_CAR_SDATE)+" "+"-"+" "+Order.get(TodayList.TAG_CAR_EDATE));
cartime.setText(Order.get(TodayList.TAG_CAR_TIME));
carddesc.setText(Order.get(TodayList.TAG_CAR_DESC));
imageLoader=new ImageLoader(activity.getApplicationContext());
imageLoader.DisplayImage(Order.get(TodayList.TAG_CAR_IMAGE), carimage);
final String carid = Order.get(TodayList.TAG_CAR_ID);
final String shareurl = Order.get(TodayList.TAG_CAR_EURL);
final String plantoattend = Order.get(TodayList.TAG_CAR_STATUS);
if ((!(LoginForm.GoogleId.equalsIgnoreCase("No user found")))
|| (!(LoginForm.FacebookId.equalsIgnoreCase("No user found")))
|| (!(CommonUtils.login_status
.equalsIgnoreCase("No user found")))) {
if(plantoattend.equalsIgnoreCase("N")){
cardetails.setImageResource(R.drawable.attend);
}
else {
cardetails.setImageResource(R.drawable.unattend);
}
}
else {
cardetails.setImageResource(R.drawable.attend);
}
cardetails.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if(plantoattend.equalsIgnoreCase("N")){
alertDialog = new AlertDialog.Builder(activity);
alertDialog.setMessage("You're going! Do you want to share the meet?");
alertDialog.setPositiveButton("Share", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Intent sendIntent = new Intent();
sendIntent.setAction(Intent.ACTION_SEND);
sendIntent.putExtra(Intent.EXTRA_TEXT, shareurl);
sendIntent.setType("text/plain");
cardetails.setImageResource(R.drawable.unattend);
activity.startActivityForResult(Intent.createChooser(sendIntent, "Share via"),1000);
}
});
alertDialog.setNegativeButton("Not now", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
cardetails.setImageResource(R.drawable.unattend);
new AttendMeet().execute(carid);
}
});
alertDialog.show();
}
else{
if (cd.isConnectingToInternet()) {
new UnAttendMeet().execute(carid);
cardetails.setImageResource(R.drawable.attend);
//Today_List_Adapter.this.notifyDataSetChanged();
}
else {
alert.showAlertDialog(activity, "Internet Connection Error",
"Please Try Again Later", false);
return;
}
}
}
}
});
carcheckin.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent sendIntent = new Intent();
sendIntent.setAction(Intent.ACTION_SEND);
sendIntent.putExtra(Intent.EXTRA_TEXT, shareurl);
sendIntent.setType("text/plain");
activity.startActivity(sendIntent);
}
});
return vi;
}
public void onActivityResult(int requestCode, int resultCode, Intent data,String... args) {
//super.onActivityResult(requestCode, resultCode, data);
switch(requestCode) {
case 1000:
Today_List_Adapter.this.notifyDataSetChanged();
break;
}
}
class AttendMeet extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
protected String doInBackground(String... args) {
try {
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("user_id", CommonUtils.login_status));
params.add(new BasicNameValuePair("event_id", args[0]));
JSONObject json = jsonParser.makeHttpRequest(url_attendmeet,
"POST", params);
Log.d("Attend Meet", json.toString());
success = json.getString("status");
if (success.equalsIgnoreCase("ok")) {
}
else
{
error = json.getString("error");
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
if (success.equalsIgnoreCase("ok")) {
cardetails.setImageResource(R.drawable.unattend);
Toast.makeText(activity.getApplicationContext(),
"The meet was successfully added on attending meet", Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(activity.getApplicationContext(),
error, Toast.LENGTH_LONG).show();
}
}
}
class UnAttendMeet extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
protected String doInBackground(String... args) {
try {
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("user_id", CommonUtils.login_status));
params.add(new BasicNameValuePair("event_id", args[0]));
JSONObject json = jsonParser.makeHttpRequest(url_unattendmeet,
"POST", params);
Log.d("UnAttend Meet", json.toString());
success = json.getString("status");
if (success.equalsIgnoreCase("ok")) {
}
else
{
error = json.getString("error");
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
if (success.equalsIgnoreCase("ok")) {
cardetails.setImageResource(R.drawable.attend);
Toast.makeText(activity,
"The meet was successfully removed from attending meet", Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(activity,
error, Toast.LENGTH_LONG).show();
}
}
}
}
编辑：
我已经更新了我的代码。
现在我已经运行了应用程序。，我得到的结果是：
如果用户点击出席图像。，功能会做得很好，然后图像从关注图像更改为不关注图像。但我再次点击了未出席的图片。，需要调用UnAttned类。但它叫只上课。你能检查一下我的代码并给我一个解决方案吗。
底层数据也需要更改，以防视图因某种原因被重新填充（例如调用notifyDataSetChanged（）、滚动出视图等）。更改此项以解决眼前的问题（订单需要是最终订单）：
...
cardetails.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if (plantoattend.equalsIgnoreCase("N")) {
alertDialog = new AlertDialog.Builder(activity);
alertDialog.setMessage("You're going! Do you want to share the meet?");
alertDialog.setPositiveButton("Share", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Intent sendIntent = new Intent();
sendIntent.setAction(Intent.ACTION_SEND);
sendIntent.putExtra(Intent.EXTRA_TEXT, shareurl);
sendIntent.setType("text/plain");
cardetails.setImageResource(R.drawable.unattend);
activity.startActivityForResult(Intent.createChooser(sendIntent, "Share via"), 1000);
}
});
alertDialog.setNegativeButton("Not now", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
Order.put(TodayList.TAG_CAR_STATUS, "Y"); // CHANGE THE UNDERLYING DATA HERE
cardetails.setImageResource(R.drawable.unattend);
new AttendMeet().execute(carid);
}
});
alertDialog.show();
} else {
if (cd.isConnectingToInternet()) {
new UnAttendMeet().execute(carid);
Order.put(TodayList.TAG_CAR_STATUS, "N"); // CHANGE THE UNDERLYING DATA HERE
cardetails.setImageResource(R.drawable.attend);
//Today_List_Adapter.this.notifyDataSetChanged();
} else {
alert.showAlertDialog(activity, "Internet Connection Error",
"Please Try Again Later", false);
return;
}
}
}
});
...
然而，我不想留下这个答案，因为我知道你会遇到更多的问题：
- 您不应该像在onPostExecute中那样直接操作ImageView。当AsyncTask完成时，视图可能已被回收并填充了其他数据。相反，如果需要，可以更改底层数据并调用notifiedDataSetChanged
- AsyncTask，不保留对（多个！）AsyncTask的引用意味着，当用户提前离开活动/片段时，您将无法取消它们。这意味着任何触摸UI的操作都会导致应用程序崩溃。虽然使用AsyncTasks执行REST请求是绝对可能的，但如果您执行的请求数量超过少数，则会很痛苦，而且会很快变得复杂。看看像Reform或Volley这样的库
- 使用findViewById查找视图很慢，会导致滚动滞后，请尝试ViewHolder模式
- 像您所做的那样在Map中存储数据"有些"有效，但非常不符合Java风格，您将不得不在代码中添加null检查，或者冒着null指针异常的风险。改为使用POJO
- 遵守命名约定，让自己和其他人更容易阅读代码
我没有查找这些点的链接，但如果需要，我会添加它们。