Android文本视图[关闭]

Question

我正在单击事件中创建一个弹出窗口，在该弹出窗口内有文本视图和按钮...

如果我在 XML 中创建一个 Id 并设置文本

TextView txt=(TextView)findViewById(R.id.text)
txt.setText("Message");

我得到一个空指针异常。 Button 也是如此。

这是我的代码

package com.examples;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.Locale;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.PopupWindow;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;

public class Main extends Activity implements OnClickListener
    {
    private final String[] months = { "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };
        private static final String tag = "Main";
        private Button selectedDayMonthYearButton;
        private Button currentMonth;
        private ImageView prevMonth;
        private ImageView nextMonth;
        private GridView calendarView;
        private GridCellAdapter adapter;
        private Calendar _calendar;
        private int month, year;
        private final DateFormat dateFormatter = new DateFormat();
        private static final String dateTemplate = "MMMM yyyy";
        private PopupWindow pw;
        TextView txt1;
        static ViewHolder holder;
        private void getRequestParameters()
            {
                Intent intent = getIntent();
                if (intent != null)
                    {
                        Bundle extras = intent.getExtras();
                        if (extras != null)
                            { 
                                if (extras != null)
                                    {
                                        Log.d(tag, "+++++----------------->" + extras.getString("params"));
                                    }
                            }
                    }
            }


        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState)
            {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.simple_calendar_view);

                _calendar = Calendar.getInstance(Locale.getDefault());
                month = _calendar.get(Calendar.MONTH);
                Log.v("Months", ""+month);
                year = _calendar.get(Calendar.YEAR);
                Log.v("YEAR", ""+year);

                selectedDayMonthYearButton = (Button) this.findViewById(R.id.selectedDayMonthYear);
                selectedDayMonthYearButton.setText("Selected: ");

                prevMonth = (ImageView) this.findViewById(R.id.prevMonth);
                prevMonth.setOnClickListener(this);

                currentMonth = (Button) this.findViewById(R.id.currentMonth);
                currentMonth.setText(dateFormatter.format(dateTemplate, _calendar.getTime()));

                nextMonth = (ImageView) this.findViewById(R.id.nextMonth);
                nextMonth.setOnClickListener(this);

                calendarView = (GridView) this.findViewById(R.id.calendar);

                // Initialised
                adapter = new GridCellAdapter(getApplicationContext(), R.id.day_gridcell, month, year);
                adapter.notifyDataSetChanged();
                calendarView.setAdapter(adapter);
        }



        @Override
        public void onClick(View v)
            {
                if (v == prevMonth)
                    {
                        if (month <= 1)
                            {
                                month = 11;
                                year--;
                            } else
                            {
                                month--;
                            }

                        adapter = new GridCellAdapter(getApplicationContext(), R.id.day_gridcell, month, year);
                        _calendar.set(year, month, _calendar.get(Calendar.DAY_OF_MONTH));
                        currentMonth.setText(months[_calendar.get(Calendar.MONTH)] + "-" +_calendar.get(Calendar.YEAR));
                        //currentMonth.setText(_calendar.getTime().toString());

                        adapter.notifyDataSetChanged();
                        calendarView.setAdapter(adapter);
                    }
                if (v == nextMonth)
                    {
                        if (month >= 11)
                            {
                                month = 0;
                                year++;
                            } else
                            {
                                month++;
                            }

                        adapter = new GridCellAdapter(getApplicationContext(), R.id.day_gridcell, month, year);
                        _calendar.set(year, month, _calendar.get(Calendar.DAY_OF_MONTH));
                        currentMonth.setText(months[_calendar.get(Calendar.MONTH)] + "-" +_calendar.get(Calendar.YEAR));
                        //currentMonth.setText(_calendar.getTime().toString());
                        adapter.notifyDataSetChanged();
                        calendarView.setAdapter(adapter);
                    }
            }

        // Inner Class
        public class GridCellAdapter extends BaseAdapter implements OnClickListener
            {
                private static final String tag = "GridCellAdapter";
                private final Context _context;
                private final List<String> list;
                private final String[] weekdays = new String[] { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };

                private final int[] daysOfMonth = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
                private final int month, year;
                int daysInMonth, prevMonthDays;
                private final int currentDayOfMonth;
                private Button gridcell;

                // Days in Current Month
                public GridCellAdapter(Context context, int textViewResourceId, int month, int year)
                    {
                        super();
                        this._context = context;
                        this.list = new ArrayList<String>();
                        this.month = month;
                        this.year = year;

                        Log.d(tag, "Month: " + month + " " + "Year: " + year);
                        Calendar calendar = Calendar.getInstance();
                        currentDayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);

                        printMonth(month, year);
                    }

                public String getItem(int position)
                    {
                        return list.get(position);
                    }

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

                private void printMonth(int mm, int yy)
                    {
                        // The number of days to leave blank at
                        // the start of this month.
                        int trailingSpaces = 0;
                        int leadSpaces = 0;
                        int daysInPrevMonth = 0;
                        int prevMonth = 0;
                        int prevYear = 0;
                        int nextMonth = 0;
                        int nextYear = 0;

                        GregorianCalendar cal = new GregorianCalendar(yy, mm, currentDayOfMonth);

                        // Days in Current Month
                        daysInMonth = daysOfMonth[mm];
                        int currentMonth = mm;
                        if (currentMonth == 11)
                            {
                                prevMonth = 10;
                                daysInPrevMonth = daysOfMonth[prevMonth];
                                nextMonth = 0;
                                prevYear = yy;
                                nextYear = yy + 1;
                            } else if (currentMonth == 0)
                            {
                                prevMonth = 11;
                                prevYear = yy - 1;
                                nextYear = yy;
                                daysInPrevMonth = daysOfMonth[prevMonth];
                                nextMonth = 1;
                            } else
                            {
                                prevMonth = currentMonth - 1;
                                nextMonth = currentMonth + 1;
                                nextYear = yy;
                                prevYear = yy;
                                daysInPrevMonth = daysOfMonth[prevMonth];
                            }

                        // Compute how much to leave before before the first day of the
                        // month.
                        // getDay() returns 0 for Sunday.
                        trailingSpaces = cal.get(Calendar.DAY_OF_WEEK) - 1;

                        if (cal.isLeapYear(cal.get(Calendar.YEAR)) && mm == 1)
                            {
                                ++daysInMonth;
                            }

                        // Trailing Month days
                        for (int i = 0; i < trailingSpaces; i++)
                            {
                                list.add(String.valueOf((daysInPrevMonth - trailingSpaces + 1) + i) + "-GREY" + "-" + months[prevMonth] + "-" + prevYear);
                            }

                        // Current Month Days
                        for (int i = 1; i <= daysInMonth; i++)
                            {
                                list.add(String.valueOf(i) + "-WHITE" + "-" + months[mm] + "-" + yy);
                            }

                        // Leading Month days
                        for (int i = 0; i < list.size() % 7; i++)
                            {
                                Log.d(tag, "NEXT MONTH:= " + months[nextMonth]);
                                list.add(String.valueOf(i + 1) + "-GREY" + "-" + months[nextMonth] + "-" + nextYear);
                            }
                    }

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

                @Override
                public View getView(int position, View convertView, ViewGroup parent)
                    {
                        Log.d(tag, "getView ...");
                        View row = convertView;
                        if (row == null)
                            {
                                // ROW INFLATION
                                Log.d(tag, "Starting XML Row Inflation ... ");
                                LayoutInflater inflater = (LayoutInflater) _context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                                row = inflater.inflate(R.layout.day_gridcell, parent, false);

                                Log.d(tag, "Successfully completed XML Row Inflation!");
                            }

                        // Get a reference to the Day gridcell
                        gridcell = (Button) row.findViewById(R.id.day_gridcell);
                        gridcell.setOnClickListener(this);

                        // ACCOUNT FOR SPACING

                        Log.d(tag, "Current Day: " + currentDayOfMonth);
                        String[] day_color = list.get(position).split("-");
                        gridcell.setText(day_color[0]);
                        gridcell.setTag(day_color[0] + "-" + day_color[2] + "-" + day_color[3]);

                        if (day_color[1].equals("GREY"))
                            {
                                gridcell.setTextColor(Color.LTGRAY);
                            }
                        if (day_color[1].equals("WHITE"))
                            {
                                gridcell.setTextColor(Color.WHITE);
                            }
                        if (position == currentDayOfMonth)
                            {
                                gridcell.setTextColor(Color.BLUE);
                            }

                        return row;
                    }





                @Override
                public void onClick(View view)
                    {

                    LayoutInflater inflater = (LayoutInflater) Main.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                     // inflate our view from the corresponding XML file
                     final View layout = inflater.inflate(R.layout.popup, (ViewGroup)findViewById(R.id.popup_menu_root));

                    String date_month_year = (String) view.getTag();

                     pw = new PopupWindow(layout, 200,75, true);
                     holder = new ViewHolder();
                        holder.text1 = (TextView) view.findViewById(R.id.pop_txt);
                        //holder.text1.setText("HIIIIIII");

                     pw.dismiss();
                     pw.showAtLocation(layout, Gravity.CENTER_VERTICAL, 10, 30);


                        Toast.makeText(getApplicationContext(), date_month_year, Toast.LENGTH_SHORT).show();
                        selectedDayMonthYearButton.setText("Selected: " + date_month_year);
                        Log.v("Button ID",""+R.id.bttn2);

                        //layout.setVisibility(View.INVISIBLE);

//                      findViewById(R.id.bttn2).setOnClickListener(
//                              new OnClickListener() {
////                                    
////                                    //LayoutInflater inflater = (LayoutInflater) Main.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
////                                     // inflate our view from the corresponding XML file
////                                   //  final View layout = inflater.inflate(R.layout.popup, (ViewGroup)findViewById(R.id.popup_menu_root));
////                                    
////
////                                    @Override
//                                  public void onClick(View arg0) {
////                                        // TODO Auto-generated method stub
//////                                       pw = new PopupWindow(layout, 200,75, true);
//////                                              
//////                                       pw.dismiss();
//////                                       pw.showAtLocation(layout, Gravity.CENTER_VERTICAL, 10, 30);
////                                        
//                                  }
//                              });
                    }
            }



        static class ViewHolder {
            TextView text1;

        }
        //list.setOnItemClickListener(new OnItemClickListener(){

    }

Answer 1

您在被点击的View 上调用findViewById()，而不是您的弹出窗口。

改变这个：

holder.text1 = (TextView) view.findViewById(R.id.pop_txt);

收件人：

holder.text1 = (TextView) pw.findViewById(R.id.pop_txt);

Answer 2

PopupWindow 不是 android 中的视图。事实上，PopupView 直接扩展了 Object - 这意味着几件事：

1. 无法从 PopupWindow 调用findViewById()，因为 PopupWindow 没有 findViewById() 方法。

2. findViewById() 尝试遍历 UI 树时，找不到其中的元素，因为 PopupWindow 实际上并不是层次结构中的 View。

3. （我认为）这意味着 PopupWindow 不能用于动态内容。您将不得不改用Dialog，它实际上有一个findViewById() 方法可用。 （Dialog 也不是 View，但它确实定义了 findViewById()。）