滚动列表视图时项目混乱（回收站）

Question

我在 listvew 的每个项目（在 TextView 中）中显示一个倒数计时器，我每秒更新一次。它工作得很好，因为每个项目都有自己正确的计时器。但是，每当列表视图变长并迫使我向下或向上滚动时，项目就会变得混乱，第一个隐藏项目显示的不是他的计时器而是第一个的计时器，这让我很难理解正在发生的事情。我知道它与 listview 回收器有关，这就是 listview 的工作方式。但是我需要解决这个问题，但我不知道如何解决。

此外，如果我删除语句 if(convertView == null)，它就会得到修复。但是当我滚动时，listview 加载会变得非常慢。

这是我正在使用的自定义适配器：

public class TicketAdapter extends ArrayAdapter<TicketModel> implements View.OnClickListener{

    private ArrayList<TicketModel> dataSet;
    Context mContext;


    // View lookup cache
    private class ViewHolder {
        TextView txtName;
        TextView txtType;
        TextView txtTempsRestant;
        TextView txtDate;
        TextView txtSLA;
        ImageView info;
        RelativeLayout layout;

        Handler handler = new Handler(){
            @Override
            public void handleMessage(Message msg) {

                Bundle bundle = msg.getData();
                long timeLeftMS = bundle.getLong("time");


                int day = (int) ((timeLeftMS / (24*3600000)));
                int hour = (int) ((timeLeftMS / (1000*60*60)) % 24);
                int minute = (int) ((timeLeftMS / (60000)) % 60);
                int second = (int)timeLeftMS % 60000 / 1000;

                String timeLeftText = "";

                if (day<10) timeLeftText += "0";
                timeLeftText += day;
                timeLeftText += ":";
                if (hour<10) timeLeftText += "0";
                timeLeftText += hour;
                timeLeftText += ":";
                if (minute<10) timeLeftText += "0";
                timeLeftText += minute;
                timeLeftText += ":";
                if (second<10) timeLeftText += "0";
                timeLeftText += seconde;

                txtTempsRestant.setText(timeLeftText); //----- This is where I'm updating my textview every second ------


            }
        };

        Handler handlerLate = new Handler(){
            @Override
            public void handleMessage(Message msg) {
                Bundle bundle = msg.getData();
                long time = bundle.getLong("time");
                if (time == -1){
                    txtTempsRestant.setText("Ancient version");
                    txtTempsRestant.setTextColor(Color.parseColor("#434343"));
                }
                else {
                    txtTempsRestant.setText("Late");
                    txtTempsRestant.setTextColor(Color.parseColor("#434343"));
                    layout.setBackgroundColor(Color.parseColor("#3caa0000"));
                    info.setImageResource(R.drawable.haute);
                }
            }
        };

        Handler handlerFinishLate = new Handler(){
            @Override
            public void handleMessage(Message msg) {
                Bundle bundle = msg.getData();
                String Nom = bundle.getString("name");
                String idTicket = bundle.getString("id");

                txtTempsRestant.setText("Late");
                txtTempsRestant.setTextColor(Color.parseColor("#434343"));
                layout.setBackgroundColor(Color.parseColor("#3caa0000"));
                info.setImageResource(R.drawable.haute);

            }
        };

        Handler handlerAttente = new Handler(){
            @Override
            public void handleMessage(Message msg) {
                txtTempsRestant.setText("En attente...");
                txtTempsRestant.setTextColor(Color.parseColor("#434343"));
                layout.setBackgroundColor(Color.parseColor("#949494"));
                info.setImageResource(R.drawable.enattente);
            }
        };

        public void startTimer(long timeLeftMS, String statut, final String Nom, final String idTicket) {
            if(statut.equals("4")){
                handlerAttente.sendEmptyMessage(0);
            }
            else{
                if (timeLeftMS<0){
                    //handlerLate.sendEmptyMessage(0);
                    Bundle bundle = new Bundle();
                    bundle.putLong("time", timeLeftMS);
                    Message message = new Message();
                    message.setData(bundle);
                    handlerLate.sendMessage(message);
                }
                else{
                    CountDownTimer countDownTimer = new CountDownTimer(timeLeftMS, 1000) {

                        @Override
                        public void onTick(long l) {
                            Bundle bundle = new Bundle();
                            bundle.putLong("time", l);
                            bundle.putString("name", Nom);
                            bundle.putString("id", idTicket);
                            Message message = new Message();
                            message.setData(bundle);
                            handler.sendMessage(message);
                        }

                        @Override
                        public void onFinish() {
                            Bundle bundle = new Bundle();
                            bundle.putString("name", Nom);
                            bundle.putString("id", idTicket);
                            Message message = new Message();
                            message.setData(bundle);
                            handlerFinishLate.sendMessage(message);
                        }
                    }.start();
                }
            }

        }

    }


    public TicketAdapter(ArrayList<TicketModel> data, Context context) {
        super(context, R.layout.row_item_ticket, data);
        this.dataSet = data;
        this.mContext=context;
    }


    @Override
    public void onClick(View v) {
        int position=(Integer) v.getTag();
        Object object= getItem(position);
        TicketModel TicketModel=(TicketModel)object;

        switch (v.getId())
        {
            case R.id.item_info:

                Snackbar.make(v, "Late? : " +TicketModel.isTicketEnRetard(), Snackbar.LENGTH_LONG)
                        .setAction("No action", null).show();
                break;
        }
    }

    private int lastPosition = -1;


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        // Get the data item for this position
        TicketModel TicketModel = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        final ViewHolder viewHolder; // view lookup cache stored in tag

        final View result;
        long timeLeft;
        String Statut;
        String Nom;
        String idTicket;
        if (convertView == null) {

            viewHolder = new ViewHolder();
            LayoutInflater inflater = LayoutInflater.from(getContext());
            convertView = inflater.inflate(R.layout.row_item_ticket, parent, false);
            viewHolder.txtName = (TextView) convertView.findViewById(R.id.titreTV);
            viewHolder.txtDate = (TextView) convertView.findViewById(R.id.dateTV);
            viewHolder.txtSLA = (TextView) convertView.findViewById(R.id.slaTV);
            viewHolder.txtTempsRestant = (TextView) convertView.findViewById(R.id.SLARestantTV);
            viewHolder.info = (ImageView) convertView.findViewById(R.id.item_info);
            viewHolder.layout = (RelativeLayout) convertView.findViewById(R.id.backgroundRow);

            timeLeft = Long.valueOf(TicketModel.getTempsRestantTicket());
            Statut = TicketModel.getStatut();
            Nom = TicketModel.getTitreTicket();
            idTicket = TicketModel.getIdTicket();

            result=convertView;

            viewHolder.startTimer(timeLeft, Statut, Nom, idTicket);

            convertView.setTag(viewHolder);

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

        viewHolder.txtName = (TextView) convertView.findViewById(R.id.titreTV);
        viewHolder.txtDate = (TextView) convertView.findViewById(R.id.dateTV);
        viewHolder.txtSLA = (TextView) convertView.findViewById(R.id.slaTV);
        viewHolder.txtTempsRestant = (TextView) convertView.findViewById(R.id.SLARestantTV);
        viewHolder.info = (ImageView) convertView.findViewById(R.id.item_info);
        viewHolder.layout = (RelativeLayout) convertView.findViewById(R.id.backgroundRow);

        timeLeft = Long.valueOf(TicketModel.getTempsRestantTicket());
        Statut = TicketModel.getStatut();
        Nom = TicketModel.getTitreTicket();
        idTicket = TicketModel.getIdTicket();


        lastPosition = position;

        viewHolder.txtName.setText(TicketModel.getTitreTicket());
        viewHolder.txtDate.setText(TicketModel.getDateTicket());
        viewHolder.txtSLA.setText(TicketModel.getSlaTicket());
        if (Long.valueOf(TicketModel.getTempsRestantTicket())<0){
            viewHolder.txtTempsRestant.setText("Late");
        }

        viewHolder.layout.setBackgroundColor(getColorBG(TicketModel.isTicketEnRetard()));
        viewHolder.info.setOnClickListener(this);
        viewHolder.info.setTag(position);

        // Return the completed view to render on screen
        return convertView;
    }


}

Answer 1

Also, if I remove the statement if(convertView == null), it'll get fixed. But the listview will become extremely slow to load when I scroll.

ListView 研究回收抓取视图的概念。当您向上滚动时，第一个状态下的视图被擦除，出现在底部的新视图与之前被擦除的视图相同。

为了克服这个问题，视图知道有多少种视图：

@Override
public int getViewTypeCount() {
    return getCount();
}

@Override
public int getItemViewType(int position) {
    return position;
}

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

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

@Override
public long getItemId(int position) {
    return 0;
}

还有确保你初始化。 ArrayList 作为 private ArrayList<TicketModel> dataSet = new ArrayList<>();

Answer 2

Hey you can create list of viewHolder class and and handle each view with timer.


public class MyRecyclerAdapter extends RecyclerView.Adapter<MyRecyclerAdapter.MyViewHolder> {
    private final List<MyViewHolder> lstHolders;
    private Context context;
    public MyRecyclerAdapter(Context context) {
        super();
        this.context = context;
        lstHolders = new ArrayList<>();
        startUpdateTimer();
    }
    private Handler mHandler = new Handler();
    private Runnable updateRemainingTimeRunnable = new Runnable() {
        @Override
        public void run() {
            synchronized (lstHolders) {
                long currentTime = System.currentTimeMillis();
                for (MyViewHolder holder : lstHolders) {
                    holder.updateTimeRemaining(currentTime);
                }
            }
        }
    };
    private void startUpdateTimer() {
        Timer tmr = new Timer();
        tmr.schedule(new TimerTask() {
            @Override
            public void run() {
                mHandler.post(updateRemainingTimeRunnable);
            }
        }, 1000, 1000);
    }
    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_view_item,parent,false);

        return new MyViewHolder(view);
    }
    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        holder.setData(position);
        synchronized (lstHolders) {
            lstHolders.add(holder);
        }
        holder.updateTimeRemaining(System.currentTimeMillis());
    }
    @Override
    public int getItemCount() {
        return 50;
    }
    public class MyViewHolder extends RecyclerView.ViewHolder{
        TextView tvTimeRemaining;
        public MyViewHolder(View itemView) {
            super(itemView);
            tvTimeRemaining = itemView.findViewById(R.id.txt_view);
        }
        public void updateTimeRemaining(long currentTime) {
            String result = getData("09/21/2018 15:00:53");
            String[] terms = result.split(",");
            long expirationTime = getInitialTimeSecond(terms);
           /* if(Integer.parseInt(terms[0])>=1){
                expirationTime = 24*60*60*60*1000;
            }else{
                expirationTime   = getInitialTimeSecond(terms);
            }*/
            long timeDiff = expirationTime;
            if (timeDiff > 0) {
                int seconds = (int) (timeDiff / 1000) % 60;
                int minutes = (int) ((timeDiff / (1000 * 60)) % 60);
                int hours = (int) ((timeDiff / (1000 * 60 * 60)) % 24);
                Spannable hourString = new SpannableString(String.valueOf(hours));
                BackgroundColorSpan backgroundSpan = new BackgroundColorSpan(Color.RED);
                hourString.setSpan(backgroundSpan, 0, hourString.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);


                tvTimeRemaining.setText(hourString + " : " + minutes + " : " + seconds + "");
            } else {
                tvTimeRemaining.setText("Expired!!");
            }
        }
        public void setData(int position) {
            updateTimeRemaining(System.currentTimeMillis());
        }
    }
    private long getInitialTimeSecond(String[] terms) {
        long mInitialTime = DateUtils.DAY_IN_MILLIS * Integer.parseInt(terms[0]) +
                DateUtils.HOUR_IN_MILLIS * Integer.parseInt(terms[1]) +
                DateUtils.MINUTE_IN_MILLIS * Integer.parseInt(terms[2]) +
                DateUtils.SECOND_IN_MILLIS * Integer.parseInt(terms[3]);
        return mInitialTime;
    }
private String getData(String dateStop) {
        //Calendar c = Calendar.getInstance();
        //HH converts hour in 24 hours format (0-23), day calculation
        SimpleDateFormat format = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
        Date d1 = Calendar.getInstance().getTime();
        Date d2 = null;
        String result = null;
        try {
            // d1 = format.parse(c.getTime().toString());
            d2 = format.parse(dateStop);
            //in milliseconds
            long diff = d2.getTime() - d1.getTime();
            long diffSeconds = diff / 1000 % 60;
            long diffMinutes = diff / (60 * 1000) % 60;
            long diffHours = diff / (60 * 60 * 1000) % 24;
            long diffDays = diff / (24 * 60 * 60 * 1000);
            result = diffDays + "," + diffHours + "," + diffMinutes + "," + diffSeconds;
            System.out.print(diffDays + " days, ");
            System.out.print(diffHours + " hours, ");
            System.out.print(diffMinutes + " minutes, ");
            System.out.print(diffSeconds + " seconds.");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }
}
if you have any doubt,Let me know.

滚动列表视图时项目混乱（回收站）

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