我试图在Fragment中单击编辑文本时打开日历。但是当我点击编辑文本时，它会向我抛出空指针异常。 相同的代码在Activity类中工作正常，但在Fargement中工作不正常。
异常
03-05 19:02:39.888: E/AndroidRuntime(1092): FATAL EXCEPTION: main
03-05 19:02:39.888: E/AndroidRuntime(1092): java.lang.NullPointerException
03-05 19:02:39.888: E/AndroidRuntime(1092): at com.test.newapp.AppTrip.showDialog(AppTrip.java:75)
03-05 19:02:39.888: E/AndroidRuntime(1092): at com.test.newapp.AppTrip$2.onClick(AppTrip.java:54)
03-05 19:02:39.888: E/AndroidRuntime(1092): at android.view.View.performClick(View.java:4212)
03-05 19:02:39.888: E/AndroidRuntime(1092): at android.view.View$PerformClick.run(View.java:17476)
03-05 19:02:39.888: E/AndroidRuntime(1092): at android.os.Handler.handleCallback(Handler.java:800)
03-05 19:02:39.888: E/AndroidRuntime(1092): at android.os.Handler.dispatchMessage(Handler.java:100)
03-05 19:02:39.888: E/AndroidRuntime(1092): at android.os.Looper.loop(Looper.java:194)
03-05 19:02:39.888: E/AndroidRuntime(1092): at android.app.ActivityThread.main(ActivityThread.java:5371)
03-05 19:02:39.888: E/AndroidRuntime(1092): at java.lang.reflect.Method.invokeNative(Native Method)
03-05 19:02:39.888: E/AndroidRuntime(1092): at java.lang.reflect.Method.invoke(Method.java:525)
03-05 19:02:39.888: E/AndroidRuntime(1092): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
03-05 19:02:39.888: E/AndroidRuntime(1092): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
03-05 19:02:39.888: E/AndroidRuntime(1092): at dalvik.system.NativeStart.main(Native Method)
片段代码
public class AppTrip extends Fragment {
View rootView;
EditText from_date, to_date;
DatePickerDialog.OnDateSetListener date;
static final int DATE_DIALOG_ID = 999;
Calendar myCalendar;
int val;
Context context;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
context = getActivity();
rootView = inflater.inflate(R.layout.main, container, false);
from_date = (EditText) rootView.findViewById(R.id.from_date);
to_date = (EditText) rootView.findViewById(R.id.to_date);
from_date.setFocusableInTouchMode(false);
to_date.setFocusableInTouchMode(false);
date = new DatePickerDialog.OnDateSetListener() {
@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
// TODO Auto-generated method stub
myCalendar.set(Calendar.YEAR, year);
myCalendar.set(Calendar.MONTH, monthOfYear);
myCalendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
updateLabel(val);
}
};
from_date.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
showDialog(DATE_DIALOG_ID);
val = 1;
}
});
to_date.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
showDialog(DATE_DIALOG_ID);
val = 2;
}
});
return rootView;
}
protected Dialog showDialog(int dateDialogId) {
final Calendar now = Calendar.getInstance();
switch (dateDialogId) {
case DATE_DIALOG_ID:
DatePickerDialog _date = new DatePickerDialog(context, date,
myCalendar.get(Calendar.YEAR),
myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH)) {
@Override
public void onDateChanged(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
if (year - now.get(Calendar.YEAR) > 1) {
view.updateDate(year - 1,
myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH));
}
if (year - now.get(Calendar.YEAR) == 1
&& monthOfYear > now.get(Calendar.MONTH)) {
view.updateDate(year, myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH));
}
if (year - now.get(Calendar.YEAR) == 1
&& monthOfYear == now.get(Calendar.MONTH)
&& dayOfMonth > now.get(Calendar.DAY_OF_MONTH)) {
view.updateDate(year, myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH));
}
if (year < now.get(Calendar.YEAR))
view.updateDate(myCalendar.get(Calendar.YEAR),
myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH));
if (monthOfYear < now.get(Calendar.MONTH)
&& year == now.get(Calendar.YEAR))
view.updateDate(myCalendar.get(Calendar.YEAR),
myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH));
if (dayOfMonth < now.get(Calendar.DAY_OF_MONTH)
&& year == now.get(Calendar.YEAR)
&& monthOfYear == now.get(Calendar.MONTH))
view.updateDate(myCalendar.get(Calendar.YEAR),
myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH));
}
};
return _date;
}
return null;
}
private void updateLabel(int val) {
String myFormat = "dd/MM/yy"; // In which you need put here
SimpleDateFormat sdf = new SimpleDateFormat(myFormat, Locale.US);
Log.d("Date value ", "===" + sdf.format(myCalendar.getTime()));
if (val == 1)
from_date.setText(sdf.format(myCalendar.getTime()));
else
to_date.setText(sdf.format(myCalendar.getTime()));
}
}
答案 0 :(得分：1)
从
改变 myCalendar.get(Calendar.YEAR),
myCalendar.get(Calendar.MONTH),
myCalendar.get(Calendar.DAY_OF_MONTH))
到
now.get(Calendar.YEAR),
now.get(Calendar.MONTH),
now.get(Calendar.DAY_OF_MONTH))
showDialog（） 方法。
您忘记在onCreateView（）上初始化 日历myCalendar;
myCalendar = Calendar.getInstance();
答案 1 :(得分：0)
您正在使用未初始化的myCalendar实例。尝试使用now而不是myCalendar。
答案 2 :(得分：0)
您的代码中的所有内容都可以在您的代码中进行两项更改
首先在onCreateView
myCalendar = Calendar.getInstance();
并添加此
_date.show();
前
return _date;
答案 3 :(得分：0)
内部片段showdialog（）方法不起作用。你可以在from_date上执行setonclicklistener并在其中调用DatePickerDialog。做与活动类相同的其他事情。 希望能帮到你。