我正在尝试创建一个自定义日历，从这里的这个例子开始，唯一的例外是我希望它在一个片段中。但是我在这里遇到了一个空点错误：gridview.setAdapter(adapter);适配器类、xml 和可绘制对象都是相同的。
package com.projectcaruso.naturalfamilyplaning;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.GregorianCalendar;
import java.util.Locale;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
public class CalendarFragment extends Fragment {
public GregorianCalendar month, itemmonth;// calendar instances.
public CalendarAdapter adapter;// adapter instance
public Handler handler;// for grabbing some event values for showing the dot
// marker.
public ArrayList<String> items; // container to store calendar items which
// needs showing the event marker
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_calendar, null);
Locale.setDefault( Locale.US );
month = (GregorianCalendar) GregorianCalendar.getInstance();
itemmonth = (GregorianCalendar) month.clone();
items = new ArrayList<String>();
adapter = new CalendarAdapter(getActivity(), month);
GridView gridview = (GridView) getActivity().findViewById(R.id.gridview);
gridview.setAdapter(adapter);
handler = new Handler();
handler.post(calendarUpdater);
TextView title = (TextView) getActivity().findViewById(R.id.title);
title.setText(android.text.format.DateFormat.format("MMMM yyyy", month));
RelativeLayout previous = (RelativeLayout) getActivity().findViewById(R.id.previous);
previous.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
setPreviousMonth();
refreshCalendar();
}
});
RelativeLayout next = (RelativeLayout) getActivity().findViewById(R.id.next);
next.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
setNextMonth();
refreshCalendar();
}
});
gridview.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
((CalendarAdapter) parent.getAdapter()).setSelected(v);
String selectedGridDate = CalendarAdapter.dayString
.get(position);
String[] separatedTime = selectedGridDate.split("-");
String gridvalueString = separatedTime[2].replaceFirst("^0*",
"");// taking last part of date. ie; 2 from 2012-12-02.
int gridvalue = Integer.parseInt(gridvalueString);
// navigate to next or previous month on clicking offdays.
if ((gridvalue > 10) && (position < 8)) {
setPreviousMonth();
refreshCalendar();
} else if ((gridvalue < 7) && (position > 28)) {
setNextMonth();
refreshCalendar();
}
((CalendarAdapter) parent.getAdapter()).setSelected(v);
showToast(selectedGridDate);
}
});
return view;
}
protected void setNextMonth() {
if (month.get(GregorianCalendar.MONTH) == month
.getActualMaximum(GregorianCalendar.MONTH)) {
month.set((month.get(GregorianCalendar.YEAR) + 1),
month.getActualMinimum(GregorianCalendar.MONTH), 1);
} else {
month.set(GregorianCalendar.MONTH,
month.get(GregorianCalendar.MONTH) + 1);
}
}
protected void setPreviousMonth() {
if (month.get(GregorianCalendar.MONTH) == month
.getActualMinimum(GregorianCalendar.MONTH)) {
month.set((month.get(GregorianCalendar.YEAR) - 1),
month.getActualMaximum(GregorianCalendar.MONTH), 1);
} else {
month.set(GregorianCalendar.MONTH,
month.get(GregorianCalendar.MONTH) - 1);
}
}
protected void showToast(String string) {
Toast.makeText(getActivity(), string, Toast.LENGTH_SHORT).show();
}
public void refreshCalendar() {
TextView title = (TextView) getActivity().findViewById(R.id.title);
adapter.refreshDays();
adapter.notifyDataSetChanged();
handler.post(calendarUpdater); // generate some calendar items
title.setText(android.text.format.DateFormat.format("MMMM yyyy", month));
}
public Runnable calendarUpdater = new Runnable() {
@Override
public void run() {
items.clear();
// Print dates of the current week
DateFormat df = new SimpleDateFormat("yyyy-MM-dd",Locale.US);
String itemvalue;
for (int i = 0; i < 7; i++) {
itemvalue = df.format(itemmonth.getTime());
itemmonth.add(GregorianCalendar.DATE, 1);
items.add("2012-09-12");
items.add("2012-10-07");
items.add("2012-10-15");
items.add("2012-10-20");
items.add("2012-11-30");
items.add("2012-11-28");
}
adapter.setItems(items);
adapter.notifyDataSetChanged();
}
};
}