使用Android TimePicker.getCurrentHour时遇到问题

Question

I'm making an app that utilizes a TimePicker, and this is my first time using it. My code is as follows:

final Dialog mTimeDialog = new Dialog(this);
TimePicker timePicker = (TimePicker)mTimeDialog.findViewById(R.id.timePicker);
TimePicker timePicker1 = (TimePicker)mTimeDialog.findViewById(R.id.timePicker1);
int starthour = timePicker.getCurrentHour();
int startminute = timePicker.getCurrentMinute();
int finishhour = timePicker1.getCurrentHour();
int finishminute = timePicker1.getCurrentMinute();

But I'm getting an exception when I try to run it. When I push the save button that triggers the onClick that this is contained in, I get this:

Caused by: java.lang.NullPointerException
 at com.csam.hourtracker.hourentry.onClick(hourentry.java:40)

Any help would be great!

Answer 1

You have the below

final Dialog mTimeDialog = new Dialog(this);
TimePicker timePicker = (TimePicker)mTimeDialog.findViewById(R.id.timePicker);

You have not set the content of layout to Dialog before initializing the TimerPicker's

You are missing

mTimeDialog.setContentView(yourview);

Hence your timepicker's are null causing NPE.

findViewById looks for a view with the id mentioned in the current infalted layout. I believe you have a custom layout for your dialog. You need to inflate the layout first and then initialize your views.