我正在Xamarin Android(基于this tutorial)上创建自己的日历.我将Java所需的所有内容都转换为C#,但是现在当我启动应用程序并打开行中包含自定义日历的片段时：
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
var view = inflater.Inflate(Resource.Layout.calendar_fragment_main, container, false); //System.NotSupportedException Error
return view;
}
我收到一个错误消息：
System.NotSupportedException – Could not activate JNI Handle 0xffcdb7e8 (key_handle 0x741b240) of Java type ‘md57f15d2d0137b5b5d70f719ce3cee21d4/EstiCalendar’ as managed type ‘EstiMOBILE.Droid.Components.EstiCalendar.Component.Layouts.EstiCalendar’.
还有另外两个错误,可能是第一个错误指出：
Java.Lang.UnsupportedOperationException – Binary XML file line #1: You must supply a layout_width attribute.
Android.Views.InflateException – Binary XML file line #1: Binary XML file line #1: You must supply a layout_width attribute.
包含自定义日历的片段(calendar_fragment_main.axml)：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:esticalendar="http://schemas.android.com/apk/res-auto"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:id="@+id/calendar_content_wrapper"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/calendar_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
tools:text="Calendar" />
<CalendarView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="@id/calendar_title"
android:id="@+id/calendar_main_object"
android:visibility="gone" />
<EstiMOBILE.Droid.Components.EstiCalendar.Component.Layouts.EstiCalendar
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/esti_calendar"
esticalendar:date_format="MMMM yyyy" />
</RelativeLayout>
</RelativeLayout>
我的自定义日历类EstiCalendar.cs
using System;
using System.Collections.Generic;
using Android.Content;
using Android.Content.Res;
using Android.Graphics;
using Android.Runtime;
using Android.Util;
using Android.Views;
using Android.Widget;
using Java.Text;
using Java.Util;
namespace EstiMOBILE.Droid.Components.EstiCalendar.Component.Layouts
{
public class EstiCalendar : LinearLayout
{
// how many days to show, defaults to six weeks, 42 days
private static readonly int DAYS_COUNT = 42;
// default date format
private static readonly string DATE_FORMAT = "MMM yyyy";
// date format
private string dateFormat;
// current displayed month
private Calendar currentDate = Calendar.Instance;
//event handling
private IEventHandler eventHandler = null;
// internal components
private LinearLayout header;
private ImageView btnPrev;
private ImageView btnNext;
private TextView txtDate;
private GridView grid;
// seasons' rainbow
int[] rainbow = new int[] {
Resource.Color.summer,
Resource.Color.fall,
Resource.Color.winter,
Resource.Color.spring
};
// month-season association (northern hemisphere, sorry australia :)
readonly int[] monthSeason = { 2, 2, 3, 3, 3, 0, 0, 0, 1, 1, 1, 2 };
public EstiCalendar(IntPtr handle, JniHandleOwnership transfer) : base(handle, transfer)
{
}
public EstiCalendar(Context context, IAttributeSet attrs) : base(context, attrs)
{
InitControl(context, attrs);
}
public EstiCalendar(Context context, IAttributeSet attrs, int defStyleAttr) : base(context, attrs, defStyleAttr)
{
InitControl(context, attrs);
}
/**
* Load control xml layout
*/
private void InitControl(Context context, IAttributeSet attrs)
{
LayoutInflater inflater = (LayoutInflater)context.GetSystemService(Context.LayoutInflaterService);
inflater.Inflate(Resource.Layout.calendar_control, this);
LoadDateFormat(attrs);
AssignUiElements();
AssignClickHandlers();
UpdateCalendar();
}
private void LoadDateFormat(IAttributeSet attrs)
{
TypedArray ta = Context.ObtainStyledAttributes(attrs, Resource.Styleable.EstiCalendar);
try
{
// try to load provided date format, and fallback to default otherwise
dateFormat = ta.GetString(Resource.Styleable.EstiCalendar_date_format);
if (dateFormat == null)
dateFormat = DATE_FORMAT;
}
finally
{
ta.Recycle();
}
}
private void AssignUiElements()
{
// layout is inflated, assign local variables to components
header = (LinearLayout)FindViewById(Resource.Id.calendar_header);
btnPrev = (ImageView)FindViewById(Resource.Id.calendar_prev_button);
btnNext = (ImageView)FindViewById(Resource.Id.calendar_next_button);
txtDate = (TextView)FindViewById(Resource.Id.calendar_date_display);
grid = (GridView)FindViewById(Resource.Id.calendar_grid);
}
private void AssignClickHandlers()
{
btnNext.Click += (sender, e) =>
{
currentDate.Add(Calendar.Month, 1);
UpdateCalendar();
};
btnPrev.Click += (sender, e) =>
{
currentDate.Add(Calendar.Month, -1);
UpdateCalendar();
};
grid.ItemLongClick += (object sender, AdapterView.ItemLongClickEventArgs e) => {
if (eventHandler != null)
{
eventHandler.OnDayLongPress((Date)e.Position);
}
};
}
public void UpdateCalendar()
{
UpdateCalendar(null);
}
/**
* Display dates correctly in grid
*/
public void UpdateCalendar(HashSet<Date> events)
{
List<Date> cells = new List<Date>();
Calendar calendar = (Calendar)currentDate.Clone();
// determine the cell for current month's beginning
calendar.Set(Calendar.DayOfMonth, 1);
int monthBeginningCell = calendar.Get(Calendar.DayOfWeek) - 1;
// move calendar backwards to the beginning of the week
calendar.Add(Calendar.DayOfMonth, -monthBeginningCell);
// fill cells
while (cells.Count < DAYS_COUNT)
{
cells.Add(calendar.Time);
calendar.Add(Calendar.DayOfMonth, 1);
}
// update grid
grid.Adapter = new CalendarAdapter(Context, cells, events);
// update title
SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
txtDate.Text = sdf.Format(currentDate.Time);
// set header color according to current season
int month = currentDate.Get(Calendar.Month);
int season = monthSeason[month];
int color = rainbow[season];
header.SetBackgroundColor(Resources.GetColor(color));
}
private class CalendarAdapter : BaseAdapter<Date>
{
// days with events
private HashSet<Date> eventDays;
private List<Date> days;
// for view inflation
private LayoutInflater inflater;
private Context context;
public CalendarAdapter(Context context, List<Date> days, HashSet<Date> eventDays) : base()
{
this.eventDays = eventDays;
this.days = days;
inflater = LayoutInflater.From(context);
this.context = context;
}
public override Date this[int position] => days[position];
public override int Count => days.Count;
public override long GetItemId(int position)
{
return position;
}
public override View GetView(int position, View convertView, ViewGroup parent)
{
// day in question
var date = GetItem(position) as Date;
int day = date.GetDate();
int month = date.Month;
int year = date.Year;
// today
Date today = new Date();
// inflate item if it does not exist yet
if (convertView == null)
convertView = inflater.Inflate(Resource.Layout.control_calendar_day, parent, false);
// if this day has an event, specify event image
convertView.SetBackgroundResource(0);
if (eventDays != null)
{
foreach (Date eventDate in eventDays)
{
if (eventDate.GetDate() == day &&
eventDate.Month == month &&
eventDate.Year == year)
{
// mark this day for event
convertView.SetBackgroundResource(Resource.Drawable.reminder);
break;
}
}
}
// clear styling
((TextView)convertView).SetTypeface(null, TypefaceStyle.Normal);
((TextView)convertView).SetTextColor(Color.Black);
if (month != today.Month || year != today.Year)
{
// if this day is outside current month, grey it out
((TextView)convertView).SetTextColor(context.Resources.GetColor(Resource.Color.greyed_out));
}
else if (day == today.GetDate())
{
// if it is today, set it to blue/bold
((TextView)convertView).SetTypeface(null, TypefaceStyle.Bold);
((TextView)convertView).SetTextColor(context.Resources.GetColor(Resource.Color.today));
}
// set text
((TextView)convertView).Text = $"{date.GetDate()}";
return convertView;
}
}
public void SetEventHandler(IEventHandler eventHandler)
{
this.eventHandler = eventHandler;
}
public interface IEventHandler
{
void OnDayLongPress(Date date);
}
}
}
CalendarFragment.cs包含错误：
using System;
using System.Collections.Generic;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using EstiMOBILE.Droid.Components.EstiCalendar.Component.Layouts;
using EstiMOBILE.Droid.Fragments.BaseFragments;
using Java.Util;
namespace EstiMOBILE.Droid.Fragments.CustomFragments
{
public class CalendarFragment : BaseFragment
{
public override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
}
public static CalendarFragment NewInstance()
{
var frag1 = new CalendarFragment { Arguments = new Bundle() };
return frag1;
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
var view = inflater.Inflate(Resource.Layout.calendar_fragment_main, container, false); //Error
//InitCustomCalendar(view);
return view;
}
public void InitCustomCalendar(View view)
{
HashSet<Date> events = new HashSet<Date>
{
new Date()
};
EstiCalendar cv = (EstiCalendar) view.FindViewById(Resource.Id.esti_calendar);
cv.UpdateCalendar(events);
}
}
}
您有什么帮助,如何摆脱这个错误？
解决方法:
您不需要其他的构造函数
public EstiCalendar(IntPtr handle, JniHandleOwnership transfer) : base(handle, transfer)
{
}
问题是Java和Xamarin之间的名称空间,您应该在XML文件中使用小写字母表示名称空间,使用camelcase表示类名称.更改您的xml文件,例如：
<estimobile.droid.components.esticalendar.component.layouts.EstiCalendar
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/esti_calendar"
esticalendar:date_format="MMMM yyyy" />