我希望在点击日期时，它会转到下一个活动。我包括意图但它不起作用。抛出空指针错误。我把这个意图放在onclick函数的不同位置，但它不起作用并抛出异常。请帮助我如何从此活动获取和转到下一个活动，并将日期作为参数
package com.examples;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
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.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;
public class SimpleCalendarViewActivity extends Activity implements OnClickListener
{
private static final String tag = "SimpleCalendarViewActivity";
private ImageView calendarToJournalButton;
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";
/** 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) + 1;
year = _calendar.get(Calendar.YEAR);
Log.d(tag, "Calendar Instance:= " + "Month: " + month + " " + "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.calendar_day_gridcell, month, year);
adapter.notifyDataSetChanged();
calendarView.setAdapter(adapter);
}
/**
*
* @param month
* @param year
*/
private void setGridCellAdapterToDate(int month, int year)
{
adapter = new GridCellAdapter(getApplicationContext(), R.id.calendar_day_gridcell, month, year);
_calendar.set(year, month - 1, _calendar.get(Calendar.DAY_OF_MONTH));
currentMonth.setText(dateFormatter.format(dateTemplate, _calendar.getTime()));
adapter.notifyDataSetChanged();
calendarView.setAdapter(adapter);
}
@Override
public void onClick(View v)
{
if (v == prevMonth)
{
if (month <= 1)
{
month = 12;
year--;
}
else
{
month--;
}
Log.d(tag, "Setting Prev Month in GridCellAdapter: " + "Month: " + month + " Year: " + year);
setGridCellAdapterToDate(month, year);
}
if (v == nextMonth)
{
if (month > 11)
{
month = 1;
year++;
}
else
{
month++;
}
Log.d(tag, "Setting Next Month in GridCellAdapter: " + "Month: " + month + " Year: " + year);
setGridCellAdapterToDate(month, year);
}
}
@Override
public void onDestroy()
{
Log.d(tag, "Destroying View ...");
super.onDestroy();
}
// ///////////////////////////////////////////////////////////////////////////////////////
// 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 static final int DAY_OFFSET = 1;
private final String[] weekdays = new String[]{"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
private final String[] months = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
private final int[] daysOfMonth = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
private final int month, year;
private int daysInMonth, prevMonthDays;
private int currentDayOfMonth;
private int currentWeekDay;
private Button gridcell;
private TextView num_events_per_day;
private final HashMap eventsPerMonthMap;
private final SimpleDateFormat dateFormatter = new SimpleDateFormat("dd-MMM-yyyy");
// 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, "==> Passed in Date FOR Month: " + month + " " + "Year: " + year);
Calendar calendar = Calendar.getInstance();
setCurrentDayOfMonth(calendar.get(Calendar.DAY_OF_MONTH));
setCurrentWeekDay(calendar.get(Calendar.DAY_OF_WEEK));
Log.d(tag, "New Calendar:= " + calendar.getTime().toString());
Log.d(tag, "CurrentDayOfWeek :" + getCurrentWeekDay());
Log.d(tag, "CurrentDayOfMonth :" + getCurrentDayOfMonth());
// Print Month
printMonth(month, year);
// Find Number of Events
eventsPerMonthMap = findNumberOfEventsPerMonth(year, month);
}
private String getMonthAsString(int i)
{
return months[i];
}
private String getWeekDayAsString(int i)
{
return weekdays[i];
}
private int getNumberOfDaysOfMonth(int i)
{
return daysOfMonth[i];
}
public String getItem(int position)
{
return list.get(position);
}
@Override
public int getCount()
{
return list.size();
}
/**
* Prints Month
*
* @param mm
* @param yy
*/
private void printMonth(int mm, int yy)
{
Log.d(tag, "==> printMonth: mm: " + mm + " " + "yy: " + 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;
int currentMonth = mm - 1;
String currentMonthName = getMonthAsString(currentMonth);
daysInMonth = getNumberOfDaysOfMonth(currentMonth);
Log.d(tag, "Current Month: " + " " + currentMonthName + " having " + daysInMonth + " days.");
// Gregorian Calendar : MINUS 1, set to FIRST OF MONTH
GregorianCalendar cal = new GregorianCalendar(yy, currentMonth, 1);
Log.d(tag, "Gregorian Calendar:= " + cal.getTime().toString());
if (currentMonth == 11)
{
prevMonth = currentMonth - 1;
daysInPrevMonth = getNumberOfDaysOfMonth(prevMonth);
nextMonth = 0;
prevYear = yy;
nextYear = yy + 1;
Log.d(tag, "*->PrevYear: " + prevYear + " PrevMonth:" + prevMonth + " NextMonth: " + nextMonth + " NextYear: " + nextYear);
}
else if (currentMonth == 0)
{
prevMonth = 11;
prevYear = yy - 1;
nextYear = yy;
daysInPrevMonth = getNumberOfDaysOfMonth(prevMonth);
nextMonth = 1;
Log.d(tag, "**--> PrevYear: " + prevYear + " PrevMonth:" + prevMonth + " NextMonth: " + nextMonth + " NextYear: " + nextYear);
}
else
{
prevMonth = currentMonth - 1;
nextMonth = currentMonth + 1;
nextYear = yy;
prevYear = yy;
daysInPrevMonth = getNumberOfDaysOfMonth(prevMonth);
Log.d(tag, "***---> PrevYear: " + prevYear + " PrevMonth:" + prevMonth + " NextMonth: " + nextMonth + " NextYear: " + nextYear);
}
// Compute how much to leave before before the first day of the
// month.
// getDay() returns 0 for Sunday.
int currentWeekDay = cal.get(Calendar.DAY_OF_WEEK) - 1;
trailingSpaces = currentWeekDay;
Log.d(tag, "Week Day:" + currentWeekDay + " is " + getWeekDayAsString(currentWeekDay));
Log.d(tag, "No. Trailing space to Add: " + trailingSpaces);
Log.d(tag, "No. of Days in Previous Month: " + daysInPrevMonth);
if (cal.isLeapYear(cal.get(Calendar.YEAR)) && mm == 1)
{
++daysInMonth;
}
// Trailing Month days
for (int i = 0; i < trailingSpaces; i++)
{
Log.d(tag, "PREV MONTH:= " + prevMonth + " => " + getMonthAsString(prevMonth) + " " + String.valueOf((daysInPrevMonth - trailingSpaces + DAY_OFFSET) + i));
list.add(String.valueOf((daysInPrevMonth - trailingSpaces + DAY_OFFSET) + i) + "-GREY" + "-" + getMonthAsString(prevMonth) + "-" + prevYear);
}
// Current Month Days
for (int i = 1; i <= daysInMonth; i++)
{
Log.d(currentMonthName, String.valueOf(i) + " " + getMonthAsString(currentMonth) + " " + yy);
if (i == getCurrentDayOfMonth())
{
list.add(String.valueOf(i) + "-BLUE" + "-" + getMonthAsString(currentMonth) + "-" + yy);
}
else
{
list.add(String.valueOf(i) + "-WHITE" + "-" + getMonthAsString(currentMonth) + "-" + yy);
}
}
// Leading Month days
for (int i = 0; i < list.size() % 7; i++)
{
Log.d(tag, "NEXT MONTH:= " + getMonthAsString(nextMonth));
list.add(String.valueOf(i + 1) + "-GREY" + "-" + getMonthAsString(nextMonth) + "-" + nextYear);
}
}
/**
* NOTE: YOU NEED TO IMPLEMENT THIS PART Given the YEAR, MONTH, retrieve
* ALL entries from a SQLite database for that month. Iterate over the
* List of All entries, and get the dateCreated, which is converted into
* day.
*
* @param year
* @param month
* @return
*/
private HashMap findNumberOfEventsPerMonth(int year, int month)
{
HashMap map = new HashMap<String, Integer>();
// DateFormat dateFormatter2 = new DateFormat();
//
// String day = dateFormatter2.format("dd", dateCreated).toString();
//
// if (map.containsKey(day))
// {
// Integer val = (Integer) map.get(day) + 1;
// map.put(day, val);
// }
// else
// {
// map.put(day, 1);
// }
return map;
}
@Override
public long getItemId(int position)
{
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
View row = convertView;
if (row == null)
{
LayoutInflater inflater = (LayoutInflater) _context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.calendar_day_gridcell, parent, false);
}
// Get a reference to the Day gridcell
gridcell = (Button) row.findViewById(R.id.calendar_day_gridcell);
gridcell.setOnClickListener(this);
// ACCOUNT FOR SPACING
Log.d(tag, "Current Day: " + getCurrentDayOfMonth());
String[] day_color = list.get(position).split("-");
String theday = day_color[0];
String themonth = day_color[2];
String theyear = day_color[3];
if ((!eventsPerMonthMap.isEmpty()) && (eventsPerMonthMap != null))
{
if (eventsPerMonthMap.containsKey(theday))
{
num_events_per_day = (TextView) row.findViewById(R.id.num_events_per_day);
Integer numEvents = (Integer) eventsPerMonthMap.get(theday);
num_events_per_day.setText(numEvents.toString());
}
}
// Set the Day GridCell
gridcell.setText(theday);
gridcell.setTag(theday + "-" + themonth + "-" + theyear);
Log.d(tag, "Setting GridCell " + theday + "-" + themonth + "-" + theyear);
if (day_color[1].equals("GREY"))
{
gridcell.setTextColor(Color.LTGRAY);
}
if (day_color[1].equals("WHITE"))
{
gridcell.setTextColor(Color.WHITE);
}
if (day_color[1].equals("BLUE"))
{
gridcell.setTextColor(getResources().getColor(R.color.static_text_color));
}
return row;
}
@Override
public void onClick(View view)
{
String date_month_year = (String) view.getTag();
selectedDayMonthYearButton.setText("Selected: " + date_month_year);
try
{
Date parsedDate = dateFormatter.parse(date_month_year);
Log.d(tag, "Parsed Date: " + parsedDate.toString());
Intent intent = new Intent(SimpleCalendarViewActivity.this,ViewReport.class);
intent.putExtra("date",parsedDate);
startActivity(intent);
}
catch (ParseException e)
{
e.printStackTrace();
}
}
public int getCurrentDayOfMonth()
{
return currentDayOfMonth;
}
private void setCurrentDayOfMonth(int currentDayOfMonth)
{
this.currentDayOfMonth = currentDayOfMonth;
}
public void setCurrentWeekDay(int currentWeekDay)
{
this.currentWeekDay = currentWeekDay;
}
public int getCurrentWeekDay()
{
return currentWeekDay;
}
}
}
答案 0 :(得分：0)
你试过而不是：
Intent intent = new Intent(SimpleCalendarViewActivity.this,ViewReport.class);
intent.putExtra("date",parsedDate);
startActivity(intent);
此：
Intent intent = new Intent(view.getContext(), ViewReport.class);
intent.putExtra("date", parsedDate);
startActivity(intent);
编辑：也不要忘记检查你的值，我只是两种方式测试（xxx.this与view.getContext（），只是解析一个新的Date（），我后来通过getSerializable，也许你的日期没有正确解析？）
答案 1 :(得分：0)
也许你的值parsedDate变为null，这就是为什么会发生这种情况。请检查该值，然后调用Intent。